Reduce Overfishing

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Protect & Manage Ecosystems
Image
An image of a fishing boat at sea
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Summary

Reduce Overfishing refers to the use of management actions that decrease fishing effort and therefore cut CO₂ emissions from fishing vessel fuel use on overfished stocks. Advantages include the potential to replenish depleted fish stocks, support ecosystem health, and enhance long-term food and job security. Disadvantages include the short-term reductions in fishing effort needed to allow systems to recover, which could impact local livelihoods and economies. While these interventions are not expected to reach globally meaningful levels of emissions reductions (>0.1 Gt CO₂‑eq/yr ), we conclude that Reduce Overfishing is “Worthwhile” with important ecosystem and social benefits.

Description for Social and Search
Our analysis concludes that, despite its limited global impact for reducing emissions, Reduce Overfishing is a “Worthwhile” climate solution that has other important benefits for ecosystem health and long-term food security.
Overview

What is our assessment?

Our analysis concludes that, despite its limited global impact for reducing emissions, Reduce Overfishing is a “Worthwhile” climate solution that has other important benefits for ecosystem health and long-term food security.

Plausible Could it work? Yes
Ready Is it ready? Yes
Evidence Are there data to evaluate it? Yes
Effective Does it consistently work? Yes
Impact Is it big enough to matter? No
Risk Is it risky or harmful? No
Cost Is it cheap? ?

What is it?

Reducing overfishing lowers fuel use and CO₂ emissions from wild capture fishing vessels by reducing fishing effort on overfished stocks. This is typically achieved through management actions, such as seasonal closures, gear restrictions, and catch limits. Fishing effort, whether measured as the hours spent fishing or distance traveled, is generally proportional to fuel use. In addition to immediate reductions in emissions, reducing overfishing can allow overfished stocks to recover, which can lead to reduced future emissions since fuel use is lowered when fish are easier to catch and harvested sustainably.

Does it work?

Reducing fishing effort in locations with depleted and overfished wild fish stocks is expected to reduce emissions from fishing vessels. When stocks are overfished, fishers must exert additional effort, traveling further and/or searching longer to make the same catch, which increases fuel use and CO₂ emissions. Reducing overfishing through management actions, such as harvest control rules, gear restrictions, seasonal closures, stronger enforcement of existing regulations, and establishment of marine protected areas, can help fish stocks recover. Other policy tools, such as reducing harmful fuel subsidies that currently enable many otherwise unprofitable fishing fleets, are also likely to result in lower fuel use and CO₂ emissions. Healthy fish stocks can be caught with lower fishing effort, translating to future fuel savings and reduced CO₂ emissions. Global estimates suggest that reductions in overfishing could avoid up to 0.08 Gt CO₂‑eq/yr, representing almost half of the entire capture fisheries sector's annual emissions (0.18 Gt CO₂‑eq/yr ).

Why are we excited?

Currently, overfishing affects more than 35% of global wild marine fish stocks, increasing by 1%, on average, every year. Reducing overfishing not only lowers fuel use and emissions but also allows overfished stocks to recover. Healthy fish stocks strengthen marine food webs and contribute to ecosystem resilience and biodiversity. Overfishing has widespread consequences for diverse marine ecosystems, such as kelp forests, where declines in fish have led to overgrazing of the kelp by sea urchins. Over time, management interventions will also likely improve the sustainability and long-term reliability of coastal livelihoods and food security by supporting sustainable fisheries.

Why are we concerned?

Policy and management tools for reducing overfishing and, by extension, fishing-related emissions come with some challenges. For instance, management measures or legal protections may not be fully effective if implementation or enforcement is weak. Management and enforcement can be particularly challenging on the high seas, where jurisdiction is limited or shared across many nations, and where illegal, unreported, and unregulated fishing can be widespread. Even when effective, fish stock recovery can take years to decades, and the costs and trade-offs are unlikely to be evenly distributed across fishing fleets. In the short term, efforts to reduce overfishing could create economic challenges for small-scale fishers who may have fewer resources and less capacity to adapt to management restrictions.

Andersen, N. F., Cavan, E. L., Cheung, W. W., Martin, A. H., Saba, G. K., & Sumaila, U. R. (2024). Good fisheries management is good carbon management. npj Ocean Sustainability, 3(1), 17. Link to source: https://doi.org/10.1038/s44183-024-00053-x

Bastardie, F., Hornborg, S., Ziegler, F., Gislason, H., & Eigaard, O. R. (2022). Reducing the fuel use intensity of fisheries: through efficient fishing techniques and recovered fish stocks. Frontiers in Marine Science, 9, 817335. Link to source: https://doi.org/10.3389/fmars.2022.817335

Food and Agriculture Organization of the United Nations. (2018). The state of world fisheries and aquaculture. Food and Agriculture Organization of the United Nations. Link to source: https://openknowledge.fao.org/handle/20.500.14283/i9540en

Food and Agriculture Organization of the United Nations. (2024). The State of World Fisheries and Aquaculture 2024 – Blue Transformation in action. Food and Agriculture Organization of the United Nations. Link to source: https://openknowledge.fao.org/handle/20.500.14283/cd0683en

Gaines, S. D., Costello, C., Owashi, B., Mangin, T., Bone, J., Molinos, J. G., ... & Ovando, D. (2018). Improved fisheries management could offset many negative effects of climate change. Science Advances, 4(8), eaao1378. Link to source: https://doi.org/10.1126/sciadv.aao1378

Gephart, J. A., Henriksson, P. J., Parker, R. W., Shepon, A., Gorospe, K. D., Bergman, K., ... & Troell, M. (2021). Environmental performance of blue foods. Nature, 597(7876), 360-365. Link to source: https://doi.org/10.1038/s41586-021-03889-2

Gulbrandsen, O. (2012). Fuel savings for small fishing vessels. Food and Agriculture Organization of the United Nations. Link to source: https://www.fao.org/4/i2461e/i2461e.pdf

Hilborn, R., Amoroso, R., Collie, J., Hiddink, J. G., Kaiser, M. J., Mazor, T., ... & Suuronen, P. (2023). Evaluating the sustainability and environmental impacts of trawling compared to other food production systems. ICES Journal of Marine Science, 80(6), 1567–1579. Link to source: https://doi.org/10.1093/icesjms/fsad115

Hoegh-Guldberg, O., Caldeira, K., Chopin, T., Gaines, S., Haugan, P., Hemer, M., ... & Tyedmers, P. (2023). The ocean as a solution to climate change: five opportunities for action. In The blue compendium: From knowledge to action for a sustainable ocean economy (pp. 619–680). Cham: Springer International Publishing. Link to source: https://oceanpanel.org/wp-content/uploads/2023/09/Full-Report_Ocean-Climate-Solutions-Update-1.pdf

Johnson, T. (2009). Fuel-Saving Measures for Fishing Industry Vessels. University of Alaska Fairbanks, Alaska Sea Grant Marine Advisory Program. Link to source: https://alaskaseagrant.org/wp-content/uploads/2022/03/ASG-57PDF-Fuel-Saving-Measures-for.pdf

Ling, S. D., Johnson, C. R., Frusher, S. D., & Ridgway, K. (2009). Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift. Proceedings of the National Academy of Sciences, 106(52), 22341–22345. Link to source: https://doi.org/10.1073/pnas.0907529106

Machado, F. L. V., Halmenschlager, V., Abdallah, P. R., da Silva Teixeira, G., & Sumaila, U. R. (2021). The relation between fishing subsidies and CO2 emissions in the fisheries sector. Ecological Economics, 185, 107057. Link to source: https://doi.org/10.1016/j.ecolecon.2021.107057

Parker, R. W., Blanchard, J. L., Gardner, C., Green, B. S., Hartmann, K., Tyedmers, P. H., & Watson, R. A. (2018). Fuel use and greenhouse gas emissions of world fisheries. Nature Climate Change, 8(4), 333–337. Link to source: https://doi.org/10.1038/s41558-018-0117-x

Pauly, D., Christensen, V., Dalsgaard, J., Froese, R., & Torres Jr, F. (1998). Fishing down marine food webs. Science, 279(5352), 860–863. Link to source: https://doi.org/10.1126/science.279.5352.860

Ritchie, H., & Roser, M. (2021). Fish and overfishing. Our World in Data. Link to source: https://ourworldindata.org/fish-and-overfishing

Sharma, R., Barange, M., Agostini, V., Barros, P., Gutierrez, N.L., Vasconcellos, M., Fernandez Reguera, D., Tiffay, C., & Levontin, P., (Eds.). (2025). Review of the state of world marine fishery resources – 2025. FAO Fisheries and Aquaculture Technical Paper, No. 721. Rome. FAO. Link to source: https://doi.org/10.4060/cd5538en

Sumaila, U. R., Ebrahim, N., Schuhbauer, A., Skerritt, D., Li, Y., Kim, H. S., ... & Pauly, D. (2019). Updated estimates and analysis of global fisheries subsidies. Marine Policy, 109, 103695. Link to source: https://doi.org/10.1016/j.marpol.2019.103695

Sumaila, U. R., & Tai, T. C. (2020). End overfishing and increase the resilience of the ocean to climate change. Frontiers in Marine Science, 7, 523. Link to source: https://doi.org/10.3389/fmars.2020.00523

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World Bank. (2017). The sunken billions revisited: Progress and challenges in global marine fisheries. World Bank Publications. Link to source: http://hdl.handle.net/10986/24056

Credits

Lead Fellow

  • Christina Richardson, Ph.D.

Internal Reviewer

  • Christina Swanson, Ph.D.
Action Word
Reduce
Solution Title
Overfishing
Classification
Worthwhile
Updated Date

Improve Manure Management

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Shift Agriculture Practices
Image
An image of a manure pit in an agricultural field
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Summary

Improved manure management refers to the use of impermeable covers and physical or chemical treatments applied during the storage and processing of wet manure. These techniques can reduce methane emissions under anaerobic storage conditions and nitrous oxide emissions under aerobic conditions. They offer multiple environmental benefits, including reduced air pollution, reduced nutrient leaching and eutrophication of downstream aquatic systems, and reduced demand for energy-intensive synthetic fertilizers. Disadvantages include a relatively small climate impact and, except for covers, high costs. Even at an optimistic level of adoption, the climate impact is unlikely to be globally meaningful (<0.1 Gt CO₂‑eq/yr ). Despite this modest climate impact, we conclude that Improve Manure Management is a “Worthwhile” solution.

Description for Social and Search
Improved manure management refers to the use of impermeable covers and physical or chemical treatments applied during the storage and processing of wet manure.
Overview

What is our assessment? 

Based on our analysis, improved manure management using impermeable covers and physical or chemical treatments will reduce emissions, although not by a globally meaningful amount. However, because these manure management techniques are broadly available, we conclude this climate solution is “Worthwhile.”

Plausible Could it work? Yes
Ready Is it ready? Yes
Evidence Are there data to evaluate it? Yes
Effective Does it consistently work? Yes
Impact Is it big enough to matter? No
Risk Is it risky or harmful? No
Cost Is it cheap? ?

What is it? 

Manure generated from industrial livestock production contains significant quantities of organic carbon and nitrogen. Under low-oxygen conditions, bacteria convert organic material in manure to methane through anaerobic decomposition. Liquid manure, particularly from pigs and cows, produces significant quantities of methane. In oxygen-rich conditions, organic nitrogen in manure undergoes chemical reactions to produce nitrous oxide. Once produced, these GHGs diffuse towards the surface of the manure storage tank, where they are emitted into the atmosphere.

Improved manure management interrupts the production or release of methane and nitrous oxide through a structural barrier, or physical or chemical treatment processes. Manure storage covers made from impermeable synthetic materials effectively prevent the release of GHGs, and can be utilized in conjunction with biogas systems for energy generation. Chemical treatments, such as acidification and the addition of additives, suppress microbial activity, thereby inhibiting methane and nitrous oxide production. Physical processes, such as aeration and temperature reduction, similarly limit optimal conditions for microbial growth. Separating the solids and liquids from manure can also reduce the potential for methane production, enabling more effective solutions such as composting and anaerobic digestion.

Does it work? 

Available technologies for manure management are mature and market-ready. However, empirical evidence of their effectiveness for reducing methane emissions is limited. Pilot studies indicate high effectiveness of manure acidification, moderate effectiveness of impermeable synthetic covers, and low effectiveness of manure additives. Except for the use of natural and synthetic impermeable covers, the overall adoption of these techniques is low. 

Why are we excited? 

Improved manure management can provide environmental benefits by reducing air pollution, preventing nutrient leaching from organic solids that settle into sludge, mitigating eutrophication in downstream aquatic ecosystems, and preventing soil acidification. In the food system, manure management allows for better alignment between crop needs and natural fertilizer characteristics. Since hauling liquid manure is expensive, manure storage and treatment methods promote efficient nutrient cycling and reduce the need for energy-intensive synthetic fertilizers. Abated methane in manure also limits ground-level ozone production upon application, thereby improving crop yields.

At the farm scale, the wide range of treatment options allows for a high level of customization in the manure management process to achieve joint goals of nutrient management, revenue generation, and emission reductions. Covers also directly mitigate risks to farmworker health and safety from manure handling, and manure treatment can further limit exposure to irritants and noxious gases, improving the health of surrounding communities.

Why are we concerned?

Compared to no treatment and other manure-related solutions, such as composting and anaerobic digesters, evidence for the effectiveness of impermeable covers and manure treatment technologies is limited. At realistic levels of adoption, improving manure management is unlikely to have a globally meaningful climate impact (<0.1 Gt CO₂‑eq/yr ). High costs are also a key barrier to wider adoption, ranging from US$110–145/t CO₂‑eq for synthetic covers to US$500–3,000/t CO₂‑eq for other treatments. 

Ambikapathi, R., Periyasamy, D., Ramesh, P., Avudainayagam, S., Makoto, W., & Evgenios, A. (2023). Effect of ozone stress on crop productivity: A threat to food security. Environmental Research, 236, 116816. Link to source: https://doi.org/10.1016/j.envres.2023.116816

Ambrose, H. W., Dalby, F. R., Feilberg, A., & Kofoed, M. V. W. (2023). Additives and methods for the mitigation of methane emission from stored liquid manure. Biosystems Engineering, 229, 209–245. Link to source: https://doi.org/10.1016/j.biosystemseng.2023.03.015

Bijay, S., & Craswell, E. (2021). Fertilizers and nitrate pollution of surface and ground water: an increasingly pervasive global problem. SN Applied Sciences, 3(4). Link to source: https://www.doi.org/10.1007/s42452-021-04521-8

Fangueiro, D., Hjorth, M., & Gioelli, F. (2015). Acidification of animal slurry--a review. J Environ Manage, 149, 46–56. Link to source: https://www.doi.org/10.1016/j.jenvman.2014.10.001

FAO. (2023a). Methane emissions in livestock and rice systems – Sources, quantification, mitigation and metrics. Rome. Link to source: https://doi.org/10.4060/cc7607en

FAO. (2023b). Pathways towards lower emissions – A global assessment of the greenhouse gas emissions and mitigation options from livestock agrifood systems. Link to source: https://doi.org/10.4060/cc9029en

Grossi, G., Goglio, P., Vitali, A., & Williams, A. G. (2019). Livestock and climate change: Impact of livestock on climate and mitigation strategies. Anim Front, 9(1), 69-76. Link to source: https://doi.org/10.1093/af/vfy034

Harrison, M. T., Cullen, B. R., Mayberry, D. E., Cowie, A. L., Bilotto, F., Badgery, W. B., Liu, K., Davison, T., Christie, K. M., Muleke, A., & Eckard, R. J. (2021). Carbon myopia: The urgent need for integrated social, economic and environmental action in the livestock sector. Glob Chang Biol, 27(22), 5726–5761.  Link to source: https://doi.org/10.1111/gcb.15816

Hegde, S., Searchinger, T., & Díaz, M. J. (2025). Opportunities for Methane Mitigation in Agriculture: Technological, Economic and Regulatory Considerations. World Resources Institute: Washington DC. Link to source: https://www.wri.org/research/opportunities-methane-mitigation-agriculture-technological-economic-regulatory

Hou, Y., Velthof, G. L., & Oenema, O. (2015). Mitigation of ammonia, nitrous oxide and methane emissions from manure management chains: a meta-analysis and integrated assessment. Glob Chang Biol, 21(3), 1293–1312. Link to source: https://doi.org/10.1111/gcb.12767

Kanter, D. R., & Brownlie, W. J. (2019). Joint nitrogen and phosphorus management for sustainable development and climate goals. Environmental Science & Policy, 92, 1–8. Link to source: https://doi.org/10.1016/j.envsci.2018.10.020

Kupper, T., Häni, C., Neftel, A., Kincaid, C., Bühler, M., Amon, B., & VanderZaag, A. (2020). Ammonia and greenhouse gas emissions from slurry storage - A review. Agriculture, Ecosystems and Environment, 300(106963). Link to source: https://doi.org/10.1016/j.agee.2020.106963

Mohankumar Sajeev, E. P., Winiwarter, W., & Amon, B. (2018). Greenhouse Gas and Ammonia Emissions from Different Stages of Liquid Manure Management Chains: Abatement Options and Emission Interactions. J Environ Qual, 47(1), 30–41. Link to source: https://doi.org/10.2134/jeq2017.05.0199

Montes, F., Meinen, R., Dell, C., Rotz, A., Hristov, A. N., Oh, J., . . . Dijkstra, J. (2013). SPECIAL TOPICS—Mitigation of methane and nitrous oxide emissions from animal operations: II. A review of manure management mitigation options. J. Anim. Sci, 91, 5070–5094. Link to source: https://doi.org/10.2527/jas.2013-6584

Mukherji, A., Arndt, C., Arango, J., Flintan, F., Derera, J., Francesconi, W., Jones, S. Loboguerrero, A. M., Merrey, D., Mockshell, J., Quintero, M., Mulat, D. G., Ringler, C., Ronchi, L., Sanchez, M. E. N., Sapkota, T., & Thilsted, S. (2023). Achieving agricultural breakthrough: A deep dive into seven technological areas. Montpellier, France. Retrieved from: Link to source: https://hdl.handle.net/10568/131852.

Niles, M. T., Wiltshire, S., Lombard, J., Branan, M., Vuolo, M., Chintala, R., & Tricarico, J. (2022). Manure management strategies are interconnected with complexity across U.S. dairy farms. PLoS One, 17(6), e0267731. Link to source: https://doi.org/10.1371/journal.pone.0267731

Nour, M. M., Field, W. E., Ni, J.-Q., & Cheng, Y.-H. (2021). Farm-Related Injuries and Fatalities Involving Children, Youth, and Young Workers during Manure Storage, Handling, and Transport. Journal of Agromedicine, 26(3), 323–333. Link to source: https://doi.org/10.1080/1059924X.2020.1795034

Overmeyer, V., Trimborn, M., Clemens, J., Holscher, R., & Buscher, W. (2023). Acidification of slurry to reduce ammonia and methane emissions: Deployment of a retrofittable system in fattening pig barns. J Environ Manage, 331, 117263. Link to source: https://doi.org/10.1016/j.jenvman.2023.117263

Park, J., Kang, T., Heo, Y., Lee, K., Kim, K., Lee, K., & Yoon, C. (2020). Evaluation of Short-Term Exposure Levels on Ammonia and Hydrogen Sulfide During Manure-Handling Processes at Livestock Farms. Saf Health Work, 11(1), 109–117. Link to source: https://doi.org/10.1016/j.shaw.2019.12.007

Sokolov, V., VanderZaag, A., Habtewold, J., Dunfield, K., Wagner-Riddle, C., Venkiteswaran, J. J., & Gordon, R. (2019). Greenhouse Gas Mitigation through Dairy Manure Acidification. J Environ Qual, 48(5), 1435–1443. Link to source: https://doi.org/10.2134/jeq2018.10.0355

VanderZaag, A., Amon, B., Bittman, S., & Kuczyński, T. (2015). Ammonia Abatement with Manure Storage and Processing Techniques. In Costs of Ammonia Abatement and the Climate Co-Benefits (pp. 75–112). Link to source: https://doi.org/10.1007/978-94-017-9722-1

Wang, Y., Dong, H., Zhu, Z., Gerber, P. J., Xin, H., Smith, P., Opio, C., Steinfeld, H., & Chadwick, D. (2017). Mitigating Greenhouse Gas and Ammonia Emissions from Swine Manure Management: A System Analysis. Environ Sci Technol, 51(8), 4503–4511. Link to source: https://doi.org/10.1021/acs.est.6b06430

Wyer, K. E., Kelleghan, D. B., Blanes-Vidal, V., Schauberger, G., & Curran, T. P. (2022). Ammonia emissions from agriculture and their contribution to fine particulate matter: A review of implications for human health. J Environ Manage, 323, 116285. Link to source: https://doi.org/10.1016/j.jenvman.2022.116285

Credits

Lead Fellow

  • Aishwarya Venkat, Ph.D.

Internal Reviewer

  • Christina Swanson, Ph.D.
Action Word
Improve
Solution Title
Manure Management
Classification
Worthwhile
Updated Date

Improve Rice Production

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Shift Agriculture Practices
Image
Rice field
Coming Soon
Off
Summary

Rice production is a significant source of methane emissions and a minor source of nitrous oxide emissions. Most rice production occurs in flooded fields called paddies, where anaerobic conditions trigger high levels of methane production. This solution includes two related practices that each reduce emissions from paddy rice production: noncontinuous flooding and nutrient management. Noncontinuous flooding is a water management technique that reduces the amount of time rice paddy soils spend fully saturated, thereby reducing methane. Unfortunately, noncontinuous flooding increases nitrous oxide emissions. Nutrient management helps to address this challenge by controlling the timing, amount, and type of fertilization to maximize plant uptake and minimize nitrous oxide emissions.

Health
Land resources,Water resources,Water quality
Description for Social and Search
Improve Rice Production is a Highly Recommended climate solution. It reduces emissions of methane and nitrous oxide, two potent greenhouse gases, by converting rice paddies from continuous flooding to noncontinuous flooding and improving nutrient management.
Overview

Rice is a staple crop of critical importance, occupying 11% of global cropland (FAOstat 2025). Rice production has higher GHG emissions than most crop production, accounting for 9% of all anthropogenic methane and 10% of cropland nitrous oxide (Wang et al., 2020). Nabuurs et al. (2022) found methane emissions from global rice production to be 0.8–1.0 Gt CO₂‑eq/yr and growing 0.4% annually.

Rice paddy systems are fields with berms and plumbing to permit the flooding of rice for the production periods, which helps with weed and pest control (rice thrives in flooded conditions, though it does not require them). Paddy rice is the main source of methane from rice production. Upland rice is grown outside of paddies and does not produce significant methane emissions, so we excluded it from this analysis. Irrigated paddies are provided with irrigation water, while rain-fed paddies are only filled by rainfall and runoff (Raffa, 2021). For this analysis, we considered both irrigated and rain-fed paddies.

Methane Reduction

Flooded rice paddies encourage the production of methane by microbes. Conventional paddy rice production uses continuous flooding, in which the paddy is flooded for the full rice production period. Several approaches can reduce methane, with the most widespread being noncontinuous flooding. This is a collection of practices (such as alternate wetting and drying) that drain the fields one or more times during the rice production period. As a result, the paddy spends less time in its methane-producing state. This can be done without reducing rice yields in many, but not all, cases, and also significantly reduces irrigation water use (Bo et al., 2022). Impacts on yields depend on soils, climate, and other variables (Cheng et al., 2022). 

Nitrous Oxide Reduction

A major drawback to noncontinuous flooding is that it increases nitrous oxide emissions from fertilizer compared to continuous flooding. High nitrogen levels in flooded paddies encourage the growth of bacteria that produce methane, reduce the natural breakdown of methane, and facilitate emissions of nitrous oxide to the atmosphere (Li et al., 2024). The effect is small compared to the mitigated emissions from methane reduction (Jiang et al., 2019), but remains serious. Use of nutrient management techniques, such as controlling fertilizer amount, type (e.g., controlled-release urea), timing, and application techniques (e.g., deep fertilization), can reduce these emissions. This is in part because nitrogen fertilizers are often overapplied, leaving room to increase efficiency without reducing rice yields (Hergoualc’h et al., 2019; Li et al., 2024). 

Other Promising Practices

Other practices also show potential but were not included in our analysis. These include the application of biochar to rice paddies and the use of rice cultivars that produce fewer emissions (Qian et al., 2023). Other approaches include saturated soil culture, System of Rice Intensification (“SRI”), ground-cover systems, raised beds, and improved irrigation and paddy infrastructure (Surendran et al., 2021). 

Note that some practices, such as incorporating rice straw or the use of compost or manure, can increase nitrous oxide emissions (Li et al., 2024). 

There is also evidence that, under some circumstances, noncontinuous flooding can sequester soil organic carbon by increasing soil organic matter. However, there are not enough data available to quantify this (Qian et al., 2023). Indeed, one meta-analysis found that noncontinuous flooding can actually lead to a decrease in soil organic carbon (Livsey et al., 2019). One complication is that many production areas plant rice two or even three times per year, and data are typically presented on a per-harvest or even per-flooded day basis. To overcome this challenge, we use data on the percentage of global irrigated rice land in single, double, and triple cropping from Carlson et al. (2016) to create weighted average values as appropriate.

Adalibieke, W., Cui, X., Cai, H., You, L., & Zhou, F. (2023). Global crop-specific nitrogen fertilization dataset in 1961–2020. Scientific Data, 10(1), Article 617. Link to source: https://doi.org/10.1038/s41597-023-02526-z

Alauddin, M., Rashid Sarker, Md. A., Islam, Z., & Tisdell, C. (2020). Adoption of alternate wetting and drying (AWD) irrigation as a water-saving technology in Bangladesh: Economic and environmental considerations. Land Use Policy, 91, Article 104430. Link to source: https://doi.org/10.1016/j.landusepol.2019.104430

Bijay-Singh, & Craswell, E. (2021). Fertilizers and nitrate pollution of surface and ground water: An increasingly pervasive global problem. SN Applied Sciences, 3(4), Article 518. Link to source: https://doi.org/10.1007/s42452-021-04521-8

Bo, Y., Jägermeyr, J., Yin, Z., Jiang, Y., Xu, J., Liang, H., & Zhou, F. (2022). Global benefits of non‐continuous flooding to reduce greenhouse gases and irrigation water use without rice yield penalty. Global Change Biology, 28(11), 3636–3650. Link to source: https://doi.org/10.1111/gcb.16132

Carlson, K. M., Gerber, J. S., Mueller, N. D., Herrero, M., MacDonald, G. K., Brauman, K. A., Havlik, P., O’Connell, C.S., Johnson, J.A., Saatchi, S., & West, P.C. (2017). Greenhouse gas emissions intensity of global croplands. Nature Climate Change, 7(1), 63–68. Link to source: https://doi.org/10.1038/nclimate3158 

Carrijo, D. R., Lundy, M. E., & Linquist, B. A. (2017). Rice yields and water use under alternate wetting and drying irrigation: A meta-analysis. Field Crops Research, 203, 173–180. Link to source: https://doi.org/10.1016/j.fcr.2016.12.002

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Credits

Lead Fellow

  • Eric Toensmeier

Contributors

  • Ruthie Burrows, Ph.D.

  • James Gerber, Ph.D.

  • Yusuf Jameel, Ph.D.

  • Daniel Jasper

  • Alex Sweeney

Internal Reviewers

  • Aiyana Bodi

  • James Gerber, Ph.D.

  • Hannah Henkin

  • Zoltan Nagy, Ph.D.

  • Ted Otte

  • Paul C. West, Ph.D.

Effectiveness

Methane Reduction

We calculated per-hectare methane emissions using Intergovernmental Panel on Climate Change (IPCC) methodology (Ogle et. al, 2019). To develop regional emissions per rice harvest, we multiplied standard regional daily baseline emissions by standard cultivation period lengths, then multiplied by the mean scaling factor for noncontinuous flooding systems. However, the total number of rice harvests per year ranged from one to three. Carlson et al. (2016) reported a global figure of harvests on rice fields: 42% were harvested once, 50% were harvested twice, and 8% were harvested three times. We used this to develop a weighted average methane emissions figure for each region. National effectiveness ranged from 1.55 to 3.29 t CO₂‑eq /ha/yr (Table 1a).

Nitrous Oxide Reduction

Using data from Adalibieke et al. (2024) and Gerber et al. (2024), we calculated the current country-level rate of nitrogen application per hectare and a target rate reflecting improved efficiency through nutrient management. For a full methodology, see the Appendix. 

In noncontinuously flooded systems, nitrous oxide emissions are 1.66 times higher per t of nitrogen applied (Hergoualc’h et al., 2019). Using the different emissions factors, we calculated total nitrous oxide emissions for 1) flooded rice with current nitrogen application rates, and 2) noncontinuously flooded rice with target nitrogen application rates. 

The effectiveness of nutrient management for each country with over 100,000 ha of rice production ranged from –0.48 to 0.11 t CO₂‑eq /ha/yr (Table 1).

Combined Reduction

Combined effectiveness of methane and nitrous oxide reduction was 1.49–3.39 t CO₂‑eq /ha/yr (Table 1).

Table 1a. Combined effectiveness at reducing emissions, by country, for noncontinuous flooding with nutrient management. 

Unit: t CO₂‑eq /ha/yr

Afghanistan 1.63
Argentina 2.70
Bangladesh 1.63
Benin 2.30
Bolivia (Plurinational State of) 2.70
Brazil 2.70
Burkina Faso 2.30
Cambodia 2.13
Cameroon 2.30
Chad 2.30
China 2.48
Colombia 2.70
Côte d'Ivoire 2.30
Democratic People's Republic of Korea 2.48
Democratic Republic of the Congo 2.30
Dominican Republic 2.70
Ecuador 2.70
Egypt 2.30
Ghana 2.30
Guinea 2.30
Guinea-Bissau 2.30
Guyana 2.70
India 1.63
Indonesia 2.13
Iran (Islamic Republic of) 3.29
Italy 3.29
Japan 2.48
Lao People's Democratic Republic 2.13
Liberia 2.30
Madagascar 2.30
Malaysia 2.13
Mali 2.30
Mozambique 2.30
Myanmar 2.13
Nepal 1.63
Nigeria 2.30
Pakistan 1.63
Paraguay 2.70
Peru 2.70
Philippines 2.13
Republic of Korea 2.48
Russian Federation 3.29
Senegal 2.30
Sierra Leone 2.30
Sri Lanka 1.63
Thailand 2.13
Turkey 3.29
Uganda 2.70
United Republic of Tanzania 2.30
United States of America 1.55
Uruguay 2.70
Venezuela (Bolivarian Republic of) 2.70
Vietnam 2.13

Unit: t CO₂‑eq /ha/yr

Afghanistan 0.03
Argentina 0.07
Bangladesh 0.06
Benin 0.03
Bolivia (Plurinational State of) 0.00
Brazil 0.00
Burkina Faso –0.02
Cambodia 0.01
Cameroon 0.00
Chad 0.01
China 0.01
Colombia –0.07
Côte d'Ivoire 0.02
Democratic People's Republic of Korea 0.02
Democratic Republic of the Congo 0.01
Dominican Republic –0.16
Ecuador –0.08
Egypt –0.15
Ghana 0.05
Guinea 0.01
Guinea-Bissau 0.01
Guyana –0.06
India –0.02
Indonesia 0.11
Iran (Islamic Republic of) –0.05
Italy 0.00
Japan 0.07
Lao People's Democratic Republic 0.02
Liberia 0.02
Madagascar 0.00
Malaysia –0.01
Mali –0.03
Mozambique 0.01
Myanmar 0.04
Nepal 0.04
Nigeria 0.01
Pakistan –0.04
Paraguay 0.01
Peru 0.09
Philippines 0.00
Republic of Korea 0.00
Russian Federation 0.04
Senegal –0.04
Sierra Leone 0.02
Sri Lanka 0.02
Thailand –0.03
Turkey 0.10
Uganda 0.00
United Republic of Tanzania 0.04
United States of America –0.05
Uruguay 0.03
Venezuela (Bolivarian Republic of) –0.48
Vietnam 0.00

Unit: t CO₂‑eq /ha rice paddies/yr

Afghanistan 1.67
Argentina 2.77
Bangladesh 1.69
Benin 2.34
Bolivia (Plurinational State of) 2.70
Brazil 2.70
Burkina Faso 2.28
Cambodia 2.15
Cameroon 2.30
Chad 2.32
China 2.48
Colombia 2.63
Côte d'Ivoire 2.32
Democratic People's Republic of Korea 2.50
Democratic Republic of the Congo 2.31
Dominican Republic 2.54
Ecuador 2.62
Egypt 2.16
Ghana 2.35
Guinea 2.32
Guinea-Bissau 2.32
Guyana 2.63
India 1.61
Indonesia 2.24
Iran (Islamic Republic of) 3.24
Italy 3.29
Japan 2.54
Lao People's Democratic Republic 2.15
Liberia 2.32
Madagascar 2.31
Malaysia 2.13
Mali 2.28
Mozambique 2.32
Myanmar 2.17
Nepal 1.67
Nigeria 2.32
Pakistan 1.59
Paraguay 2.71
Peru 2.79
Philippines 2.14
Republic of Korea 2.47
Russian Federation 3.33
Senegal 2.27
Sierra Leone 2.32
Sri Lanka 1.65
Thailand 2.10
Turkey 3.39
Uganda 2.31
United Republic of Tanzania 2.35
United States of America 1.49
Uruguay 2.72
Venezuela (Bolivarian Republic of) 2.22
Vietnam 2.13
Left Text Column Width

Table 1b. Combined effectiveness at reducing emissions, by country, for noncontinuous flooding with nutrient management. 

Unit: t CO₂‑eq /ha rice paddies/yr

Afghanistan 4.75
Argentina 7.85
Bangladesh 4.75
Benin 6.71
Bolivia (Plurinational State of) 7.85
Brazil 7.85
Burkina Faso 6.71
Cambodia 6.21
Cameroon 6.71
Chad 6.71
China 7.20
Colombia 7.85
Côte d'Ivoire 6.71
Democratic People's Republic of Korea 7.20
Democratic Republic of the Congo 6.71
Dominican Republic 7.85
Ecuador 7.85
Egypt 6.71
Ghana 6.71
Guinea 6.71
Guinea-Bissau 6.71
Guyana 7.85
India 4.75
Indonesia 6.21
Iran (Islamic Republic of) 9.57
Italy 9.57
Japan 7.20
Lao People's Democratic Republic 6.21
Liberia 6.71
Madagascar 6.71
Malaysia 6.21
Mali 6.71
Mozambique 6.71
Myanmar 6.21
Nepal 4.75
Nigeria 6.71
Pakistan 4.75
Paraguay 7.85
Peru 7.85
Philippines 6.21
Republic of Korea 7.20
Russian Federation 9.57
Senegal 6.71
Sierra Leone 6.71
Sri Lanka 4.75
Thailand 6.21
Turkey 9.57
Uganda 6.71
United Republic of Tanzania 6.71
United States of America 4.51
Uruguay 7.85
Venezuela (Bolivarian Republic of) 7.85
Vietnam 6.21

Unit: t CO₂‑eq /ha rice paddies/yr

Afghanistan 0.03
Argentina 0.07
Bangladesh 0.06
Benin 0.03
Bolivia (Plurinational State of) 0.00
Brazil 0.00
Burkina Faso 0.02
Cambodia 0.01
Cameroon 0.00
Chad 0.01
China 0.01
Colombia –0.07
Côte d'Ivoire 0.02
Democratic People's Republic of Korea 0.02
Democratic Republic of the Congo 0.01
Dominican Republic 0.16
Ecuador –0.08
Egypt –0.15
Ghana 0.05
Guinea 0.01
Guinea-Bissau 0.01
Guyana –0.06
India –0.02
Indonesia 0.11
Iran (Islamic Republic of) –0.05
Italy 0.00
Japan 0.07
Lao People's Democratic Republic 0.02
Liberia 0.02
Madagascar 0.00
Malaysia –0.01
Mali –0.03
Mozambique 0.01
Myanmar 0.04
Nepal 0.04
Nigeria 0.01
Pakistan –0.04
Paraguay 0.01
Peru 0.09
Philippines 0.00
Republic of Korea 0.00
Russian Federation 0.04
Senegal –0.04
Sierra Leone 0.02
Sri Lanka 0.02
Thailand –0.03
Turkey 0.10
Uganda 0.00
United Republic of Tanzania 0.04
United States of America –0.05
Uruguay 0.03
Venezuela (Bolivarian Republic of) –0.48
Vietnam 0.00

Unit: t CO₂‑eq /ha rice paddies/yr

Afghanistan 4.78
Argentina 7.93
Bangladesh 4.81
Benin 6.74
Bolivia (Plurinational State of) 7.85
Brazil 7.85
Burkina Faso 6.68
Cambodia 6.22
Cameroon 6.71
Chad 6.72
China 7.21
Colombia 7.21
Côte d'Ivoire 6.73
Democratic People's Republic of Korea 7.23
Democratic Republic of the Congo 6.71
Dominican Republic 7.69
Ecuador 7.77
Egypt 6.56
Ghana 6.76
Guinea 6.72
Guinea-Bissau 6.72
Guyana 7.79
India 4.73
Indonesia 6.31
Iran (Islamic Republic of) 9.52
Italy 9.57
Japan 7.27
Lao People's Democratic Republic 6.23
Liberia 6.72
Madagascar 6.71
Malaysia 6.20
Mali 6.20
Mozambique 6.72
Myanmar 6.25
Nepal 4.79
Nigeria 6.72
Pakistan 4.71
Paraguay 7.86
Peru 7.95
Philippines 6.21
Republic of Korea 7.20
Russian Federation 9.61
Senegal 6.67
Sierra Leone 6.73
Sri Lanka 4.77
Thailand 6.18
Turkey 9.67
Uganda 6.71
United Republic of Tanzania 6.75
United States of America 4.45
Uruguay 7.88
Venezuela (Bolivarian Republic of) 7.38
Vietnam 6.20
Left Text Column Width
Cost

For conventional paddy rice, we assumed an initial cost of US$0 because many millions of hectares of paddies are already in place (Table 2). We used regional per-hectare average profits from Damania et al. (2024) as the source for net profit per year. Because the initial cost per hectare is US$0, the net cost per hectare is the negative of the per-hectare annual profit.

Table 2. Net cost and profit of conventional paddy rice by region in 2023.

Unit: US$/ha rice paddies

Africa 0.00
East Asia 0.00
Europe 0.00
North America 0.00
South America 0.00
South Asia 0.00
Southeast Asia 0.00

Unit: US$/ha rice paddies/yr

Africa 457.34
East Asia 543.67
Europe 585.43
North America 356.27
South America 285.69
South Asia 488.85
Southeast Asia 322.13

Unit: US$/ha rice paddies/yr

Africa -457.34
East Asia -543.67
Europe -585.43
North America -356.27
South America -285.69
South Asia -488.85
Southeast Asia -322.13
Left Text Column Width

For noncontinuous flooding, we assumed an initial cost of US$0 because no new inputs or changes to paddy infrastructure are required in most cases. Median impact on net profit was an increase of 17% based on nine data points from seven sources. National results are shown in Table 3.

We assumed nutrient management has an initial cost of US$0 because in many cases, nutrient management begins with reducing the overapplication of fertilizer. Here we used the mean value from Gu et al. (2023), a savings of US$507.8/t nitrogen. We used our national-level data on overapplication of nitrogen to calculate savings per hectare. National results are shown in Table 3.

Combined Net Profit per Hectare

Net profit per hectare varies by country due to regional and some country-specific variables. Country-by-country results are shown in Table 3.

Net Net Cost Compared to Conventional Paddy Rice

Net net cost varies by country. Country-by-country results are shown in Table 3.

Table 3. Net cost and profit of noncontinuous flooding with nutrient management by region.

Unit: US$/ha rice paddies

Afghanistan 0.00
Argentina 0.00
Bangladesh 0.00
Benin 0.00
Bolivia (Plurinational State of) 0.00
Brazil 0.00
Burkina Faso 0.00
Cambodia 0.00
Cameroon 0.00
Chad 0.00
China 0.00
Colombia 0.00
Cote d'Ivoire 0.00
Democratic People's Republic of Korea 0.00
Democratic Republic of the Congo 0.00
Dominican Republic 0.00
Ecuador 0.00
Egypt 0.00
Ghana 0.00
Guinea 0.00
Guinea–Bissau 0.00
Guyana 0.00
India 0.00
Indonesia 0.00
Iran (Islamic Republic of) 0.00
Italy 0.00
Japan 0.00
Lao People's Democratic Republic 0.00
Liberia 0.00
Madagascar 0.00
Malaysia 0.00
Mali 0.00
Mozambique 0.00
Myanmar 0.00
Nepal 0.00
Nigeria 0.00
Pakistan 0.00
Paraguay 0.00
Peru 0.00
Philippines 0.00
Republic of Korea 0.00
Russian Federation 0.00
Senegal 0.00
Sierra Leone 0.00
Sri Lanka 0.00
Thailand 0.00
Turkey 0.00
Uganda 0.00
United Republic of Tanzania 0.00
United States of America 0.00
Uruguay 0.00
Venezuela (Bolivarian Republic of) 0.00
Vietnam 0.00

Non-continuous flooding and nutrient management.

Unit: US$/ha rice paddies/yr

Afghanistan 573.4
Argentina 354.8
Bangladesh 576.7
Benin 535.1
Bolivia (Plurinational State of) 354.1
Brazil 363.4
Burkina Faso 553.3
Cambodia 377.8
Cameroon 543.7
Chad 535.1
China 675.1
Colombia 397.7
Cote d'Ivoire 535.8
Democratic People's Republic of Korea 654.6
Democratic Republic of the Congo 535.6
Dominican Republic 428.4
Ecuador 390.3
Egypt 802.2
Ghana 535.5
Guinea 538.5
Guinea–Bissau 539.2
Guyana 382.0
India 607.9
Indonesia 382.3
Iran (Islamic Republic of) 726.7
Italy 567.9
Japan 636.0
Lao People's Democratic Republic 377.0
Liberia 535.3
Madagascar 535.0
Malaysia 401.2
Mali 561.0
Mozambique 535.5
Myanmar 380.7
Nepal 575.2
Nigeria 537.1
Pakistan 610.0
Paraguay 385.9
Peru 351.7
Philippines 399.5
Republic of Korea 678.2
Russian Federation 475.2
Senegal 569.9
Sierra Leone 535.1
Sri Lanka 591.1
Thailand 407.7
Turkey 694.5
Uganda 543.3
United Republic of Tanzania 537.4
United States of America 490.4
Uruguay 377.6
Venezuela (Bolivarian Republic of) 546.2
Vietnam 416.6

Non-continuous flooding and nutrient management.

Unit: US$/ha rice paddies/yr

Afghanistan -573.4
Argentina -354.8
Bangladesh -576.7
Benin -535.1
Bolivia (Plurinational State of) -354.1
Brazil -363.4
Burkina Faso -553.3
Cambodia -377.8
Cameroon -543.7
Chad -535.1
China -675.1
Colombia -397.7
Cote d'Ivoire -535.8
Democratic People's Republic of Korea -654.6
Democratic Republic of the Congo -535.6
Dominican Republic -428.4
Ecuador -390.3
Egypt -802.2
Ghana -535.5
Guinea -538.5
Guinea–Bissau -539.2
Guyana -382.0
India -607.9
Indonesia -382.3
Iran (Islamic Republic of) -726.7
Italy -567.9
Japan -636.0
Lao People's Democratic Republic -377.0
Liberia -535.3
Madagascar -535.0
Malaysia -401.2
Mali -561.0
Mozambique -535.5
Myanmar -380.7
Nepal -575.2
Nigeria -537.1
Pakistan -610.0
Paraguay -385.9
Peru -351.7
Philippines -399.5
Republic of Korea -678.2
Russian Federation -475.2
Senegal -569.9
Sierra Leone -535.1
Sri Lanka -591.1
Thailand -407.7
Turkey -694.5
Uganda -543.3
United Republic of Tanzania -537.4
United States of America -490.4
Uruguay -377.6
Venezuela (Bolivarian Republic of) -546.2
Vietnam -416.6

Non-continuous flooding and nutrient management.

Unit: US$/ha rice paddies/yr

Afghanistan -1,062
Argentina -640.5
Bangladesh -1,065
Benin -992.4
Bolivia (Plurinational State of) -639.8
Brazil -649.0
Burkina Faso -1,010
Cambodia -699.9
Cameroon -1,001
Chad -992.5
China -1,219
Colombia -683.4
Cote d'Ivoire -993.2
Democratic People's Republic of Korea -1,198
Democratic Republic of the Congo -992.9
Dominican Republic -714.1
Ecuador -676.0
Egypt -1,387
Ghana -992.8
Guinea -995.8
Guinea–Bissau -996.5
Guyana -667.7
India -1,096
Indonesia -704.5
Iran (Islamic Republic of) -1,312
Italy -1,053
Japan -1,179
Lao People's Democratic Republic -699.1
Liberia -992.6
Madagascar -992.4
Malaysia -723.3
Mali -1,018
Mozambique -992.8
Myanmar -702.8
Nepal -1,064
Nigeria -994.5
Pakistan -1,098
Paraguay -671.6
Peru -637.4
Philippines -721.6
Republic of Korea -1,221
Russian Federation -865.9
Senegal -1,027
Sierra Leone -992.4
Sri Lanka -1,080
Thailand -729.8
Turkey -1,279
Uganda -1,000
United Republic of Tanzania -994.7
United States of America -846.7
Uruguay -663.3
Venezuela (Bolivarian Republic of) -831.9
Vietnam -738.8

Non-continuous flooding and nutrient management.

Unit: US$/t CO₂‑eq  

Afghanistan -222.1
Argentina -80.82
Bangladesh -221.5
Benin -147.2
Bolivia (Plurinational State of) -81.49
Brazil -82.60
Burkina Faso -151.2
Cambodia -112.5
Cameroon -149.3
Chad -147.7
China -168.9
Colombia -87.77
Cote d'Ivoire -147.6
Democratic People's Republic of Korea -165.8
Democratic Republic of the Congo -147.9
Dominican Republic -92.82
Ecuador -86.99
Egypt -211.5
Ghana -146.9
Guinea -148.1
Guinea–Bissau -148.2
Guyana -85.72
India -232.1
Indonesia -111.5
Iran (Islamic Republic of) -137.8
Italy -110.0
Japan -162.2
Lao People's Democratic Republic -112.2
Liberia -147.6
Madagascar -147.9
Malaysia -116.6
Mali -152.2
Mozambique -147.7
Myanmar -112.4
Nepal -222.2
Nigeria -148.0
Pakistan -233.3
Paraguay -85.41
Peru -80.22
Philippines -116.1
Republic of Korea -169.7
Russian Federation -90.08
Senegal -154.0
Sierra Leone -147.5
Sri Lanka -226.3
Thailand -118.1
Turkey -132.3
Uganda -149.1
United Republic of Tanzania -147.3
United States of America -190.1
Uruguay -84.18
Venezuela (Bolivarian Republic of) -112.7
Vietnam -119.1

Non-continuous flooding and nutrient management.

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Cost per unit climate impact

The cost per t CO₂‑eq varies by country. Country-by-country results are shown in Table 3. The global weighted average is a savings of US$175.0/t CO₂‑eq (Table 4). Note that this is the same for both 100- and 20-yr results.

Table 4. Weighted average cost per unit climate impact.

Unit: US$/t CO₂‑eq

Weighted average -175.0
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Methods and Supporting Data

Methods and Supporting Data

Learning Curve

Learning curve data are not available for improved rice cultivation.

Speed of Action

Speed of action refers to how quickly a climate solution physically affects the atmosphere after it is deployed. This is different from speed of deployment, which is the pace at which solutions are adopted.

At Project Drawdown, we define the speed of action for each climate solution as gradual, emergency brake, or delayed.

The noncontinuous flooding component of Improve Rice Production is an EMERGENCY BRAKE climate solution. It has a disproportionately fast impact after implementation because it reduces the short-lived climate pollutant methane. 

The nutrient management component is a GRADUAL climate solution. It has a steady, linear impact on the atmosphere. The cumulative effect over time builds as a straight line.

Caveats

Caveats like additionality and permanence do not apply to improve rice production as described here. If its carbon sequestration component were included, those caveats would apply.

Current Adoption

Noncontinuous Flooding

Rigorous, up-to-date country-level data about the extent of noncontinuous flooding in rice production are in short supply. We found five sources reporting adoption in seven major rice-producing countries. We used these to create regional averages and applied them to all countries that produce more than 100,000 ha of rice (paddy and upland). The total estimated current adoption is 48.65 Mha, or 47% of global rice paddy area (Table 5). This should be considered an extremely rough estimate. 

The available sources encompass different forms of noncontinuous flooding, including alternate wetting and drying (Philippines, Vietnam, Bangladesh), mid-season drainage (Japan), or both (China). 

Table 5. Current adoption level (2025).

Unit: Mha

Mean 48.65

Noncontinuous flooding, ha installed.

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Nutrient Management

We based nutrient management adoption on our analysis of the overapplication of nitrogen fertilizer on a national basis. Rather than calculate adoption in a parallel way to noncontinuous flooding, this approach provided a national average overapplication rate (the amount of nitrogen fertilizer which is applied that is not needed for crop growth and ends up as nitrous oxide emissions). We assume that every hectare of noncontinuous flooding is also using nutrient management. 

Adoption Trend

We assume the adoption of both noncontinuous flooding and nutrient management for each hectare.

Adoption trend information here takes the form of annual growth rate (%), with a median of 3.76% (Table 6). Adoption rate data are somewhat scarce. 

Table 6. Adoption trend.

Unit: %

25th percentile 3.00
Median (50th percentile) 3.76
75th percentile 4.25

Percent annual growth rate.

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Adoption Ceiling

There are barriers to adoption of these techniques and practices. Not all paddy rice is suitable for improved water management, and under certain conditions, undesirable yield reductions are possible (Bo et al., 2022). Other challenges include water access, coordinating water usage between multiple users, and ownership of water pumps (Nabuurs et al., 2022).

There are many challenges in estimating paddy rice land. Food and Agriculture Organization (FAO) statistics can overcount because land that produces more than one crop is double or triple counted. Satellite imagery is often blocked by clouds in the tropical humid areas where rice paddies are concentrated. 

A comprehensive effort to calculate total world rice paddy land reported 66.00 Mha of irrigated paddy and 63.00 Mha of rain-fed paddy (Salmon et al., 2015). Our own calculation of the combined paddy rice area of countries producing over 100,000 ha of rice found 104.1 Mha of paddy rice.

We summed high-resolution maps of paddy rice area appropriate for noncontinuous flooding (Bo et al., 2022) over maps of irrigated and rain-fed rice areas (Salmon et al., 2015) to determine a maximum adoption ceiling for each country. Several countries have already exceeded this threshold, and we included their higher adoption in our calculation. The sum of these, and therefore, the median adoption ceiling, is 77.53 Mha (Table 7).

Table 7. Adoption ceiling: upper limit for adoption level.

Unit: Mha

Median 77.53

Mha of improved rice production installed.

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Achievable Adoption

Table 8. Range of achievable adoption levels.

Unit: Mha

Current adoption 48.65
Achievable – low 49.56
Achievable – high 77.53
Adoption ceiling 77.53

Mha of improved rice production installed.

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Given that both China and Japan have already attained adoption rates above our adoption ceiling (Bo et al., 2022; Zhang et al., 2019), we selected for our adoption ceiling our Achievable – High adoption level, which is 77.53 Mha (Table 8).

In contrast, the countries with the lowest adoption rates had rates under 3%. In the absence of a modest adoption example, we chose to use current adoption plus 10% as our Achievable – Low adoption level. This provides an adoption of 49.56 Mha.

As described under Adoption Ceiling above, adoption of nutrient management is already weighted based on regional or national adoption and should not be overcounted in the achievable range calculations.

We calculated the potential impact of improved rice, on a 100-yr basis, at 0.10 Gt CO₂‑eq/yr from current adoption, and 0.10, 0.16, and 0.16 from Achievable – Low, Achievable – High, and Adoption Ceiling, respectively (Table 9). On a 20-yr basis, the totals are 0.29, 0.29, 0.46, and 0.46, respectively.

Table 9. Climate impact at different levels of adoption.

Unit: Gt CO₂‑eq/yr

Current adoption 0.10
Achievable – low 0.10
Achievable – high 0.16
Adoption ceiling 0.16

Unit: Gt CO₂‑eq/yr

Current adoption 0.29
Achievable – low 0.29
Achievable – high 0.46
Adoption ceiling 0.46
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The IPCC estimated a technical potential at 0.3 Gt CO₂‑eq/yr, with 0.2 Gt CO₂‑eq/yr as economically achievable at US$100/t CO₂ (100-yr basis; Nabuurs et al., 2022). Achieving the adoption ceiling of 76% of global flooded rice production could reduce rice paddy methane by 47% (Bo et al., 2022). Applying this percentage to the IPCC reported total paddy methane emissions of 0.49–0.73 Gt CO₂‑eq/yr yields a reduction of 0.23–0.34 Gt CO₂‑eq/yr (Nabuurs et al., 2022). Roe et al. (2021) calculated 0.19 Gt CO₂‑eq/yr. Note that these benchmarks only calculate methane from paddy rice, while we also addressed nitrous oxide from nutrient management.

Additional Benefits

The additional benefits of improved rice production arise from both practices (noncontinuous flooding and improved nutrient management) that form this solution. 

Health

Noncontinuous flooding can reduce the accumulation of arsenic in rice grains (Ishfaq et al., 2020). Arsenic is a carcinogen that is responsible for thousands of premature deaths in South and Southeast Asia (Jameel et al., 2021). The amount of arsenic reduced can vary by 0–90% depending upon the timing of the wetting and drying periods (Ishfaq et al., 2020).

Land Resources

Better nutrient management improves soil fertility and health, increasing resilience to extreme heat and droughts. Noncontinuous flooding also slows down the rate of soil salinization, protecting soil from degradation (Carrijo et al., 2017). 

Water Resources

Rice irrigation is responsible for 40% of all freshwater use in Asia, and rice requires two to three times more water per metric ton of grain than other cereals (Surendran et al., 2021). Field studies across South and Southeast Asia have shown that noncontinuous flooding can typically reduce irrigation requirements 20–30% compared to conventional flooded systems (Suwanmaneepong et al., 2023; Carrijo et al., 2017) without adversely affecting rice yield or grain quality. This reduction in water usage alleviates pressure on water resources in drought-prone areas (Alauddin et al., 2020).

Adoption of noncontinuous flooding up to the adoption ceiling of 76% would reduce rice irrigation needs by 25%. 

Water Quality

Both noncontinuous flooding and improved nutrient management reduce water pollution. Nitrogen utilization is generally poor using existing growing techniques, with two-thirds of the nitrogen fertilizer being lost through surface runoff and denitrification (Zhang et al., 2021). While noncontinuous flooding is primarily a water-efficiency and methane reduction technique, it can improve nitrogen use efficiency and reduce nitrogen runoff into water bodies (Liang et al., 2017; Liang et al., 2023). Improved nutrient management also reduces the excess fertilizers that could end up in local water bodies. Both mechanisms can mitigate eutrophication and harmful algal blooms, protect aquatic ecosystems, and ensure safer drinking water supplies (Bijay-Sing and Craswell, 2021). 

Risks

Not all paddies are suitable, with variables including soil type, irrigation infrastructure and ownership, community partitioning and scheduling of water resources, field size, and more (Nabuurs et al., 2022; Enriquez et al., 2021).

Many rice farmers in Asia do not directly control irrigation access, but instead use a municipal system, which is not always available when needed for noncontinuous flooding production. In addition, they may not actually experience cost savings, as pricing may be based on area rather than amount of water. An additional change is that multiple plots owned or rented by multiple farmers may be irrigated by a single irrigation gate, meaning that all must agree to an irrigation strategy. Generally speaking, pump-based irrigation areas see the best adoption, with poor adoption in gravity-based irrigation system areas. Improved irrigation infrastructure is necessary to increase adoption of noncontinuous flooding (Enriquez et al., 2021). 

Continuously flooded paddies have lower weed pressure than noncontinuous paddies, so noncontinuous flooding can raise labor costs or increase herbicide use. Not all rice varieties grow well in noncontinuous flooding (Li et al., 2024). In addition, it is difficult for farmers, especially smallholders, to monitor soil moisture level, which makes determining the timing of the next irrigation difficult (Livsey et al., 2019). 

Interactions with Other Solutions

We did not identify any aligned or competing interactions with other solutions.

Dashboard

Solution Basics

ha rice paddies

t CO₂-eq (100-yr)/unit/yr
2.03
units
Current 4.865×10⁷ 04.956×10⁷7.753×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.1 0.10.16
US$ per t CO₂-eq
-175
Emergency Brake

CH₄ , N₂O

Trade-offs

In some cases, rice yields are reduced (Nabuurs et al., 2022). However, this has been excluded from our calculations because we worked from the adoption ceiling of Bo et al. (2022), which explicitly addresses the question of maximum adoption without reducing yields.

Long-term impacts on soil health of water-saving irrigation strategies have not been widely studied, but a meta-analysis by Livsey et al. (2019) indicates a risk of decreases in soil carbon and fertility.

% of area
0100

Paddy rice area, 2020

Rice is the third most widely grown crop in terms of cultivated area and provides more calories directly to people than any other crop. It also is an important source of methane emissions. Here we show pixels in which at least 1% of the area is devoted to paddy (flooded) rice. Upland (unflooded) rice is included in the Improve Nutrient Management solution.

Cao, P., Bilotto, F., Gonzalez Fischer, C., Mueller, N. D., Carlson, K. M., Gerber, J.S., Smith, P., Tubiello, F. N., West, P. C., You, L., & Herrero, M. (2025). Mapping greenhouse gas emissions from global cropland circa 2020 [Data set, PREPRINT Version 1]. In review at Nature Climate Change. Link to source: https://doi.org/10.21203/rs.3.rs-6622054/v1 

Tang, F. H. M., Nguyen, T. H., Conchedda, G., Casse, L., Tubiello, F. N., & Maggi, F. (2024). CROPGRIDS: A global geo-referenced dataset of 173 crops [Data set]. Scientific Data, 11(1), 413. Link to source: https://doi.org/10.1038/s41597-024-03247-7

% of area
0100

Paddy rice area, 2020

Rice is the third most widely grown crop in terms of cultivated area and provides more calories directly to people than any other crop. It also is an important source of methane emissions. Here we show pixels in which at least 1% of the area is devoted to paddy (flooded) rice. Upland (unflooded) rice is included in the Improve Nutrient Management solution.

Cao, P., Bilotto, F., Gonzalez Fischer, C., Mueller, N. D., Carlson, K. M., Gerber, J.S., Smith, P., Tubiello, F. N., West, P. C., You, L., & Herrero, M. (2025). Mapping greenhouse gas emissions from global cropland circa 2020 [Data set, PREPRINT Version 1]. In review at Nature Climate Change. Link to source: https://doi.org/10.21203/rs.3.rs-6622054/v1 

Tang, F. H. M., Nguyen, T. H., Conchedda, G., Casse, L., Tubiello, F. N., & Maggi, F. (2024). CROPGRIDS: A global geo-referenced dataset of 173 crops [Data set]. Scientific Data, 11(1), 413. Link to source: https://doi.org/10.1038/s41597-024-03247-7

Maps Introduction

Improved rice production has its greatest potential in regions where there is substantial paddy rice production and adequate water availability to allow farmers to implement drain/flood cycles throughout the growing season (noncontinuous flooding). Rice production is dominated by Asia, so the greatest potential for solution uptake is there. Brazil and the United States rank 9th and 11th for rice production, and each has regions where this solution would have multiple benefits. Because improved rice production solution may not decrease yields, not all paddy rice-growing areas are suitable. There are regions of great potential throughout Southeast Asia, particularly in Vietnam and Thailand.

Other factors besides biophysical factors govern the suitability of noncontinuous flooding. For example, farmers are more likely to release water in their fields if they are confident that water will be available for subsequent irrigation, which often depends on community structures. 

There is very scarce information on adoption of noncontinuous flooding, although Bangladesh, China, Japan, and South Korea have relatively high uptake.

Action Word
Improve
Solution Title
Rice Production
Classification
Highly Recommended
Lawmakers and Policymakers
  • Set national targets for improving rice production and incorporate them into planning documents such as Nationally Determined Contributions.
  • If possible and appropriate, encourage rice farmers to adopt noncontinuous flooding.
  • Use policies and regulations to improve nutrient management by focusing on the four principles – right rate, right type of fertilizer, right time, and right place.
  • Invest in research and development to improve rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Invest in research and development to improve water monitoring technology and discover alternative fertilizers.
  • Improve the reliability of water irrigation systems.
  • Work with farmers and private organizations to improve data collection on advanced cultivation uptake and water management.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Practitioners
  • Practice noncontinuous flooding.
  • Take advantage of financial incentives such as tax rebates and subsidies for improved rice cultivation.
  • Improve nutrient management by focusing on the four principles – right rate, right type of fertilizer, right time, and right place.
  • Plant improved rice varieties that require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Work with policymakers and private organizations to improve data collection on advanced cultivation uptake and water management.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Business Leaders
  • Source food from farms that practice improved rice cultivation.
  • Invest in companies that utilize improved rice cultivation techniques or produce the necessary inputs.
  • Promote products that employ improved rice cultivation techniques and educate consumers about the importance of the practice.
  • Enter into offtake agreements for rice grown with improved techniques.
  • Invest in research and development to improve rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Invest in research and development to improve water monitoring technology and identify alternative fertilizers.
  • Work with farmers and private organizations to improve data collection on advanced cultivation uptake and water management.
  • Advocate to policymakers for improved rice cultivation techniques, incentives, and regulations.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Nonprofit Leaders
  • Source food from farms that practice improved rice cultivation.
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Engage with businesses to encourage corporate responsibility and/or monitor rice production.
  • Help develop rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Help improve water monitoring technology and develop alternative fertilizers.
  • Work with farmers and other private organizations to improve data collection on advanced cultivation uptake and water management.
  • Advocate to policymakers for improved rice cultivation techniques, incentives, and regulations.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Investors
  • Ensure portfolio companies and company procurement use improved rice cultivation techniques.
  • Offer financial services, including low-interest loans, micro-financing, and grants to support improving rice cultivation.
  • Invest in electronically-traded funds (ETFs); environmental, social and governance (ESG) funds; and green bonds issued by companies committed to improved rice cultivation.
  • Invest in companies developing technologies that support improved nutrient management, such as precision fertilizer applicators, alternative fertilizers, soil management equipment, and software.
  • Invest in start-ups that aim to improve rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Philanthropists and International Aid Agencies
  • Work with agricultural supply chain sources to ensure partners employ improved rice production methods, if relevant.
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Offer financial services, including low-interest loans, micro-financing, and grants to support improving rice cultivation.
  • Engage with businesses to encourage corporate responsibility and/or monitor rice production.
  • Help develop rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Help improve water monitoring technology and identify alternative fertilizers.
  • Work with farmers and other private organizations to improve data collection on advanced cultivation uptake and water management.
  • Advocate to policymakers for improved rice cultivation techniques, incentives, and regulations.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Thought Leaders
  • Source rice from farms that practice improved rice cultivation.
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Engage with businesses to encourage corporate responsibility and/or monitor rice production.
  • Help develop rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.
  • Help improve water monitoring technology and identify alternative fertilizers.
  • Work with farmers and other private organizations to improve data collection on advanced cultivation uptake and water management.
  • Advocate to policymakers for improved rice cultivation techniques, incentives, and regulations.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Technologists and Researchers
  • Improve technology and cost-effectiveness of precision fertilizer application, slow-release fertilizer, alternative organic fertilizers, nutrient recycling, and monitoring equipment.
  • Create tracking and monitoring software to support farmers' decision-making.
  • Research the application of AI and robotics for precise fertilizer application and water management.
  • Improve data and analytics to monitor soil and water quality, assist farmers, support policymaking, and assess the impacts of policies.
  • Improve rice methane emissions modeling and monitoring using all available technologies such as satellites, low-flying instruments, and on-the-ground methods.
  • Develop education and training applications to promote improved rice cultivation techniques and provide real-time feedback.
  • Improve data collection on water management and advanced cultivation uptake.
  • Improve rice varieties to require less water, have shorter growth periods, produce higher yields, and tolerate more stress.

Further information:

Communities, Households, and Individuals
  • Purchase rice from farms or suppliers that practice improved rice cultivation.
  • Engage with businesses to encourage corporate responsibility and/or monitor rice production.
  • Work with farmers and other private organizations to improve data collection on advanced cultivation uptake and water management.
  • Advocate to policymakers for improved rice cultivation techniques, incentives, and regulations.
  • Join, create, or participate in partnerships or certification programs dedicated to improving rice cultivation.

Further information:

Sources
Evidence Base

There is high consensus on the effectiveness and potential of noncontinuous flooding and nutrient management (Jiang et al., 2019; Zhang et al., 2023; Nabuurs et al., 2022; Qian et al., 2023). 

Hergoualc’h et al. (2019) describe methane reduction and associated nitrous oxide increase from noncontinuous flooding in detail(2019). Bo et al. (2022) calculate that 76% of global rice paddy area is suitable to switch to noncontinuous flooding without reducing yields. Carlson et al. (2016) provide emissions intensities for croplands, including rice production. Ludemann et al. (2024) provide country-by-country and crop-by-crop fertilizer use data. Qian et al. (2023) review methane emissions production and reduction potential.

The results presented in this document summarize findings from 12 reviews and meta-analyses and 26 original studies reflecting current evidence from countries across the Asian rice production region. We recognize this limited geographic scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

Appendix

In this analysis, we calculated the potential for reducing crop nitrogen inputs and associated nitrous oxide emissions by integrating spatially explicit, crop-specific data on nitrogen inputs, crop yields, attainable yields, irrigated extent, and climate. Broadly, we calculated a “target” yield-scaled nitrogen input rate based on pixels with low yield gaps and calculated the difference between nitrous oxide emissions under the current rate and under the hypothetical target emissions rate, using nitrous oxide emissions factors disaggregated by fertilizer type and climate. 

Emissions Factors

We used Tier 1 emissions factors from the IPCC 2019 Refinement to the 2006 Guidelines for National Greenhouse Gas Inventories, including direct emissions factors as well as indirect emissions from volatilization and leaching pathways. Direct emissions factors represent the proportion of applied nitrogen emitted as nitrous oxide, while we calculated volatilization and leaching emissions factors by multiplying the proportion of applied nitrogen lost through these pathways by the proportion of volatilized or leached nitrogen ultimately emitted as nitrous oxide. Including both direct and indirect emissions, organic and synthetic fertilizers emit 4.97 kg CO₂‑eq/kg nitrogen and 8.66 kg CO₂‑eq/kg nitrogen, respectively, in wet climates, and 2.59 kg CO₂‑eq/kg nitrogen and 2.38 kg CO₂‑eq/kg nitrogen in dry climates. We included uncertainty bounds (2.5th and 97.5th percentiles) for all emissions factors. 

We classified each pixel as “wet” or “dry” using an aridity index (AI) threshold of 0.65, calculated as the ratio of annual precipitation to potential evapotranspiration (PET) from TerraClimate data (1991–2020), based on a threshold of 0.65. For pixels in dry climates that contained irrigation, we took the weighted average of wet and dry emissions factors based on the fraction of cropland that was irrigated (Mehta et al., 2024). We excluded irrigated rice from this analysis due to large differences in nitrous oxide dynamics in flooded rice systems.

Current, Target, and Avoidable Nitrogen Inputs and Emissions

Using highly disaggregated data on nitrogen inputs from Adalibieke et al. (2024) for 21 crop groups, we calculated total crop-specific inputs of synthetic and organic nitrogen. We then averaged over 2016–2020 to reduce the influence of interannual variability in factors like fertilizer prices. These values are subsequently referred to as “current” nitrogen inputs. We calculated nitrous oxide emissions under current nitrogen inputs as the sum of the products of nitrogen inputs and the climatically relevant emissions factors for each fertilizer type.

Next, we calculated target nitrogen application rates in terms of kg nitrogen per ton of crop yield using data on actual and attainable yields for 17 crops from Gerber et al., 2024. For each crop, we first identified pixels in which the ratio of actual to attainable yields was above the 80th percentile globally. The target nitrogen application rate was then calculated as the 20th percentile of nitrogen application rates across low-yield-gap pixels. Finally, we calculated total target nitrogen inputs as the product of actual yields and target nitrogen input rates. We calculated hypothetical nitrous oxide emissions from target nitrogen inputs as the product of nitrogen inputs and the climatically relevant emissions factor for each fertilizer type.

The difference between current and target nitrogen inputs represents the amount by which nitrogen inputs could hypothetically be reduced without compromising crop productivity (i.e., “avoidable” nitrogen inputs). We calculated avoidable nitrous oxide emissions as the difference between nitrous oxide emissions with current nitrogen inputs and those with target nitrogen inputs. For crops for which no yield or attainable yield data were available, we applied the average percent reduction in nitrogen inputs under the target scenario from available crops to the nitrogen input data for missing crops to calculate the avoidable nitrogen inputs and emissions. 

This simple and empirically driven method aimed to identify realistically low but nutritionally adequate nitrogen application rates by including only pixels with low yield gaps, which are unlikely to be substantially nutrient-constrained. We did not control for other factors affecting nitrogen availability, such as historical nutrient application rates or depletion, rotation with nitrogen fixing crops, or tillage and residue retention practices.

Updated Date

Reduce Crop Residue Burning

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Shift Agriculture Practices
Image
Cornfield with crop residue
Coming Soon
On
Description for Social and Search
The Reduce Crop Residue Burning solution is coming soon.
Methods and Supporting Data

Methods and Supporting Data

Action Word
Reduce
Solution Title
Crop Residue Burning
Classification
Highly Recommended
Updated Date

Improve Irrigation Water Use Efficiency

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Shift Agriculture Practices
Image
Irrigation efficiency
Coming Soon
Off
Summary

Irrigation water use efficiency involves reducing water use without compromising crop productivity by improving irrigation scheduling and/or equipment. Irrigation produces GHG emissions by altering biogeochemical cycling of carbon and nitrogen cycles in water and soils, and through energy use for pumping. Reducing the duration of soil saturation, the amount of groundwater extracted, and the total volume of water pumped can help reduce associated emissions. However, data on the effectiveness of improved water use efficiency in reducing emissions remain very limited. We will "Keep Watching" this solution as additional data become available.

Description for Social and Search
The Improve Irrigation Efficiency solution is coming soon.
Overview

What is our assessment?

Improving irrigation water use efficiency is a promising strategy for reducing emissions. However, additional data are needed to evaluate the magnitude of its impact and its effectiveness, especially under different environmental and management conditions. Therefore, this solution is classified as "Keep Watching."

Plausible Could it work? Yes
Ready Is it ready? Yes
Evidence Are there data to evaluate it? Limited
Effective Does it consistently work? ?
Impact Is it big enough to matter? ?
Risk Is it risky or harmful? No
Cost Is it cheap? Yes

What is it? 

Improving irrigation water use efficiency involves optimizing the timing, volume, and method of irrigation to reduce water use while still meeting crop water demand, thereby reducing emissions from soils, extracted groundwater, and pumping. Irrigation is the practice of adding water to croplands or pastures to reduce crop water stress and increase productivity. However, irrigation also creates wet soil conditions that promote nitrous oxide emissions, releases greenhouse gases that had been dissolved in groundwater, and, in some cases, uses energy to pump water. Increasing water use efficiency will reduce the duration of near-saturated soil conditions, potentially reducing nitrous oxide emissions from soils. For the ~40% of global irrigated croplands that rely on groundwater, increasing water use efficiency will reduce emissions from groundwater. For irrigation systems that use pumps powered by fossil fuels or non-renewable electricity, improving water use efficiency can also reduce pumping-related emissions. Of note, energy use for pumping is also addressed by Deploy Electric Irrigation Pumps. 

Does it work?

Although the mechanisms by which improved irrigation water use efficiency can reduce emissions from soils, groundwater, and pumping are scientifically sound, the effectiveness of this solution is context-dependent, and data on effectiveness and potential impact are very limited.

Irrigation contributes to nitrous oxide emissions by stimulating denitrification, a microbial process that produces nitrous oxide emissions and tends to occur when soils are nearly saturated with water. Reducing the frequency and duration of near-saturated conditions through improved irrigation water use efficiency will likely reduce associated pulses of nitrous oxide emissions. One recent study reported that irrigation increased nitrous oxide emissions from U.S. croplands by 2.9 Mt CO₂‑eq/yr. However, data on nitrous oxide emissions under different types of irrigation management, including improved water use efficiency, are not yet available.

For croplands irrigated with groundwater, reducing water use will directly reduce emissions from groundwater degassing. Groundwater is often supersaturated in CO₂, meaning that it contains more dissolved CO₂ gas than the atmosphere. The excess CO₂ in groundwater accumulates from two sources: 1) the air space in soils tends to have high CO₂ concentrations from microbial respiration, and groundwater absorbs some of the CO₂ as it percolates through the soil profile; and 2) groundwater reacts with carbonate-containing minerals in aquifers. Similarly, dissolved nitrous oxide can also accumulate in groundwater, particularly in regions with heavy fertilizer use. However, the concentration of these GHGs in groundwater remains uncertain as it varies substantially between aquifers. Recent studies have estimated that degassing of CO₂ from groundwater produces 1.7–3.6 Mt CO₂‑eq/yr in the U.S., and one global study reported 6 Mt CO₂‑eq/yr ; however, many uncertainties remain in these studies. 

For croplands that already rely on pumps for irrigation, improving irrigation scheduling to reduce water use will reduce emissions from energy use. However, other croplands rely on surface water and gravity irrigation methods and do not require pumps. For these croplands, switching to sprinklers or drip irrigation will increase water use efficiency but will also require the addition of pumps and associated energy use emissions. 

Why are we excited?

Irrigation has a tremendous impact on the planet, accounting for nearly 90% of human-caused consumptive water use. Globally, around 23% of croplands are irrigated. Therefore, opportunities to increase water use efficiency abound, and improvements in irrigation water management can have widespread impacts. Many places are facing surface water shortages and groundwater depletion, and improving irrigation practices is a critical part of sustainable water management as resource availability changes. Increases in irrigation water use efficiency have the potential to help alleviate water scarcity when coupled with appropriate policy reforms. Moreover, reducing water use can also reduce energy and water costs for producers, and reductions in runoff can improve water quality and slow erosion, benefitting biodiversity and soil health. 

Why are we concerned?

Due to limited data, the effects of irrigation on emissions from groundwater and soils remain poorly understood. Additional data, including direct field measurements, are needed before we can confidently assess the effectiveness of improved irrigation water use efficiency in reducing emissions. The effectiveness of this solution depends on environmental and management conditions, the extent to which water use is reduced, and the method used to improve irrigation water use efficiency. 

It is important that improvements in irrigation water use efficiency do not compromise crop yields. Efforts to improve irrigation water use efficiency that impose water stress and reduce yields can lead to the expansion of agricultural land, resulting in the loss of carbon-rich ecosystems.

Anand, S. K., Rosa, L., Mohanty, B. P., Rajan, N., & Calabrese, S. (2025). Balancing productivity and climate impact: A framework to assess climate-smart irrigation. Earth’s Future, 13(11), Article e2025EF006116. Link to source: https://doi.org/10.1029/2025EF006116

Bateman, E. J., & Baggs, E. M. (2005). Contributions of nitrification and denitrification to N2O emissions from soils at different water-filled pore space. Biology and Fertility of Soils, 41(6), 379–388. Link to source: https://doi.org/10.1007/s00374-005-0858-3

Butterbach-Bahl, K., Baggs, E. M., Dannenmann, M., Kiese, R., & Zechmeister-Boltenstern, S. (2013). Nitrous oxide emissions from soils: How well do we understand the processes and their controls? Philosophical Transactions of the Royal Society B: Biological Sciences, 368(1621), Article 20130122. Link to source: https://doi.org/10.1098/rstb.2013.0122

Driscoll, A. W., Marston, L. T., Ogle, S. M., Planavsky, N. J., Siddik, M. A. B., Spencer, S., Zhang, S., & Mueller, N. D. (2024). Hotspots of irrigation-related US greenhouse gas emissions from multiple sources. Nature Water, 2(9), 837–847. Link to source: https://doi.org/10.1038/s44221-024-00283-w

Elberling, B. B., Kovács, G. M., Hansen, H. F. E., Fensholt, R., Ambus, P., Tong, X., Gominski, D., Mueller, C. W., Poultney, D. M. N., & Oehmcke, S. (2023). High nitrous oxide emissions from temporary flooded depressions within croplands. Communications Earth & Environment, 4(1), Article 1. Link to source: https://doi.org/10.1038/s43247-023-01095-8

Flint, E. M., Ascott, M. J., Gooddy, D. C., Stahl, M. O., & Surridge, B. W. J. (2025). Anthropogenic water withdrawals modify freshwater inorganic carbon fluxes across the United States. Environmental Science & Technology, 59(8), 3949–3960. Link to source: https://doi.org/10.1021/acs.est.4c09426

Huo, P., & Gao, P. (2024). Degassing of greenhouse gases from groundwater under different irrigation methods: A neglected carbon source in agriculture. Agricultural Water Management, 301, 108941. Link to source: https://doi.org/10.1016/j.agwat.2024.108941

Huo, P., Li, H., Huang, X., Ma, X., Liu, L., Ji, W., Liu, Y., & Gao, P. (2022). Dissolved greenhouse gas emissions from agricultural groundwater irrigation in the Guanzhong Basin of China. Environmental Pollution, 309, Article 119714. Link to source: https://doi.org/10.1016/j.envpol.2022.119714

Kebede, E. A., Oluoch, K. O., Siebert, S., Mehta, P., Hartman, S., Jägermeyr, J., Ray, D., Ali, T., Brauman, K. A., Deng, Q., Xie, W., & Davis, K. F. (2025). A global open-source dataset of monthly irrigated and rainfed cropped areas (MIRCA-OS) for the 21st century. Scientific Data, 12(1), 208. Link to source: https://doi.org/10.1038/s41597-024-04313-w

McDermid, S., Mahmood, R., Hayes, M. J., Bell, J. E., & Lieberman, Z. (2021). Minimizing trade-offs for sustainable irrigation. Nature Geoscience, 14(10), 706–709. Link to source: https://doi.org/10.1038/s41561-021-00830-0

McDermid, S., Nocco, M., Lawston-Parker, P., Keune, J., Pokhrel, Y., Jain, M., Jägermeyr, J., Brocca, L., Massari, C., Jones, A. D., Vahmani, P., Thiery, W., Yao, Y., Bell, A., Chen, L., Dorigo, W., Hanasaki, N., Jasechko, S., Lo, M.-H., … Yokohata, T. (2023). Irrigation in the Earth system. Nature Reviews Earth & Environment, 4, 435–453. Link to source: https://doi.org/10.1038/s43017-023-00438-5

McGill, B. M., Hamilton, S. K., Millar, N., & Robertson, G. P. (2018). The greenhouse gas cost of agricultural intensification with groundwater irrigation in a Midwest U.S. row cropping system. Global Change Biology, 24(12), 5948–5960. Link to source: https://doi.org/10.1111/gcb.14472

Qin, J., Duan, W., Zou, S., Chen, Y., Huang, W., & Rosa, L. (2024). Global energy use and carbon emissions from irrigated agriculture. Nature Communications, 15(1), Article 3084. Link to source: https://doi.org/10.1038/s41467-024-47383-5

Rosa, L., Chiarelli, D. D., Sangiorgio, M., Beltran-Peña, A. A., Rulli, M. C., D’Odorico, P., & Fung, I. (2020). Potential for sustainable irrigation expansion in a 3 °C warmer climate. Proceedings of the National Academy of Sciences, 117(47), 29526–29534. Link to source: https://doi.org/10.1073/pnas.2017796117

Wood, W. W., & Hyndman, D. W. (2017). Groundwater depletion: A significant unreported source of atmospheric carbon dioxide. Earth’s Future, 5(11), 1133–1135. Link to source: https://doi.org/10.1002/2017EF000586

Yang, Y., Jin, Z., Mueller, N. D., Driscoll, A. W., Hernandez, R. R., Grodsky, S. M., Sloat, L. L., Chester, M. V., Zhu, Y.-G., & Lobell, D. B. (2023). Sustainable irrigation and climate feedbacks. Nature Food, 4(8), Article 8. Link to source: https://doi.org/10.1038/s43016-023-00821-x

Credits

Lead Fellow

Avery Driscoll, Ph.D.

Internal Reviewers

Christina Swanson, Ph.D.

Heather McDiarmid, Ph.D.

James Gerber, Ph.D.

Action Word
Improve
Solution Title
Irrigation Water Use Efficiency
Classification
Keep Watching
Updated Date

Improve Nutrient Management

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Shift Agriculture Practices
Image
Farm equipment applying fertilizer selectively
Coming Soon
Off
Summary

We define the Improve Nutrient Management solution as reducing excessive nitrogen use on croplands. Nitrogen is critical for crop production and is added to croplands as synthetic or organic fertilizers and through microbial activity. However, farmers often add more nitrogen to croplands than crops can use. Some of that excess nitrogen is emitted to the atmosphere as nitrous oxide, a potent GHG. 

Droughts
Income & work,Food security,Health
Nature protection
Description for Social and Search
Improve Nutrient Management is a Highly Recommended climate solution. Wise use of fertilizers reduces GHG emissions while ensuring crops get nutrients they need.
Overview

Agriculture is the dominant source of human-caused emissions of nitrous oxide (Tian et al., 2020). Nitrogen is critical for plant growth and is added to croplands in synthetic forms, such as urea, ammonium nitrate, or anhydrous ammonia; in organic forms, such as manure or compost; and by growing legume crops, which host microbes that capture nitrogen from the air and add it to the soil (Adalibieke et al., 2023; Ludemann et al., 2024). If more nitrogen is added than crops can use, the excess can be converted to other forms, including nitrous oxide, through microbial processes called denitrification and nitrification (Figure 1; Reay et al., 2012).

Figure 1. The agricultural nitrogen cycle represents the key pathways by which nitrogen is added to croplands and lost to the environment, including as nitrous oxide. The “4R” nutrient management principles – right source, right rate, right time, right place – increase the proportion of nitrogen taken up by the plant, therefore reducing nitrogen losses to the environment.

Diagram of agricultural nitrogen cycle.

Illustrations: BioRender CC-BY 4.0

Farmers can reduce nitrous oxide emissions from croplands by using the right amount and the right type of fertilizer at the right time and in the right place (Fixen, 2020; Gao & Cabrera Serrenho, 2023). Together, these four “rights” increase nitrogen use efficiency – the proportion of applied nitrogen that the crop uses (Congreves et al., 2021). Improved nutrient management is often a win-win for the farmer and the environment, reducing fertilizer costs while also lowering nitrous oxide emissions (Gu et al., 2023).

Improving nutrient management involves reducing the amount of nitrogen applied to match the crop’s requirements in areas where nitrogen is currently overapplied. A farmer can implement the other three principles – type, time, and place – in a number of ways. For example, fertilizing just before planting instead of after the previous season’s harvest better matches the timing of nitrogen addition to that of plant uptake, reducing nitrous oxide emissions before the crop is planted. Certain types of fertilizers are better suited for maximizing plant uptake, such as extended-release fertilizers, which allow the crop to steadily absorb nutrients over time. Techniques such as banding, in which farmers apply fertilizers in concentrated bands close to the plant roots instead of spreading them evenly across the soil surface, also reduce nitrous oxide emissions. Each of these practices can increase nitrogen use efficiency and decrease the amount of excess nitrogen lost as nitrous oxide (Gao & Cabrera Serrenho, 2023; Gu et al., 2023; Wang et al., 2024; You et al., 2023).

For this solution, we estimated a target rate of nitrogen application for major crops as the 20th percentile of the current rate of nitrogen application (in t N/t crop) in areas where yields are near a realistic ceiling. Excess nitrogen was defined as the amount of nitrogen applied beyond the target rate (see Adoption and Appendix for more details). Our emissions estimates include nitrous oxide from croplands, fertilizer runoff, and fertilizer volatilization. They do not include emissions from fertilizer manufacturing, which are addressed in the Deploy Low-Emission Industrial Feedstocks and Boost Industrial Efficiency solutions. We excluded nutrient management on pastures from this solution due to data limitations and address nutrient management in paddy rice systems in the Improve Rice Production solution instead. 

Adalibieke, W., Cui, X., Cai, H., You, L., & Zhou, F. (2023). Global crop-specific nitrogen fertilization dataset in 1961–2020. Scientific Data, 10(1), 617. Link to source: https://doi.org/10.1038/s41597-023-02526-z

Almaraz, M., Bai, E., Wang, C., Trousdell, J., Conley, S., Faloona, I., & Houlton, B. Z. (2018). Agriculture is a major source of NOx pollution in California. Science Advances, 4(1), eaao3477. Link to source: https://doi.org/10.1126/sciadv.aao3477

Antil, R. S., & Raj, D. (2020). Integrated nutrient management for sustainable crop production and improving soil health. In R. S. Meena (Ed.), Nutrient Dynamics for Sustainable Crop Production (pp. 67–101). Springer. Link to source: https://doi.org/10.1007/978-981-13-8660-2_3

Bijay-Singh, & Craswell, E. (2021). Fertilizers and nitrate pollution of surface and ground water: An increasingly pervasive global problem. SN Applied Sciences, 3(4), 518. Link to source: https://doi.org/10.1007/s42452-021-04521-8

Chivenge, P., Saito, K., Bunquin, M. A., Sharma, S., & Dobermann, A. (2021). Co-benefits of nutrient management tailored to smallholder agriculture. Global Food Security, 30, 100570. Link to source: https://doi.org/10.1016/j.gfs.2021.100570

Deng, J., Guo, L., Salas, W., Ingraham, P., Charrier-Klobas, J. G., Frolking, S., & Li, C. (2018). Changes in irrigation practices likely mitigate nitrous oxide emissions from California cropland. Global Biogeochemical Cycles, 32(10), 1514–1527. Link to source: https://doi.org/10.1029/2018GB005961

Domingo, N. G. G., Balasubramanian, S., Thakrar, S. K., Clark, M. A., Adams, P. J., Marshall, J. D., Muller, N. Z., Pandis, S. N., Polasky, S., Robinson, A. L., Tessum, C. W., Tilman, D., Tschofen, P., & Hill, J. D. (2021). Air quality–related health damages of food. Proceedings of the National Academy of Sciences, 118(20), e2013637118. Link to source: https://doi.org/10.1073/pnas.2013637118

Elberling, B. B., Kovács, G. M., Hansen, H. F. E., Fensholt, R., Ambus, P., Tong, X., Gominski, D., Mueller, C. W., Poultney, D. M. N., & Oehmcke, S. (2023). High nitrous oxide emissions from temporary flooded depressions within croplands. Communications Earth & Environment, 4(1), 1–9. Link to source: https://doi.org/10.1038/s43247-023-01095-8

Fixen, P. E. (2020). A brief account of the genesis of 4R nutrient stewardship. Agronomy Journal, 112(5), 4511–4518. Link to source: https://doi.org/10.1002/agj2.20315

Foley, J. A., Ramankutty, N., Brauman, K. A., Cassidy, E. S., Gerber, J. S., Johnston, M., Mueller, N. D., O’Connell, C., Ray, D. K., West, P. C., Balzer, C., Bennett, E. M., Carpenter, S. R., Hill, J., Monfreda, C., Polasky, S., Rockström, J., Sheehan, J., Siebert, S., … Zaks, D. P. M. (2011). Solutions for a cultivated planet. Nature, 478(7369), 337–342. Link to source: https://doi.org/10.1038/nature10452

Gao, Y., & Cabrera Serrenho, A. (2023). Greenhouse gas emissions from nitrogen fertilizers could be reduced by up to one-fifth of current levels by 2050 with combined interventions. Nature Food, 4(2), 170–178. Link to source: https://doi.org/10.1038/s43016-023-00698-w

Gerber, J. S., Carlson, K. M., Makowski, D., Mueller, N. D., Garcia de Cortazar-Atauri, I., Havlík, P., Herrero, M., Launay, M., O’Connell, C. S., Smith, P., & West, P. C. (2016). Spatially explicit estimates of nitrous oxide emissions from croplands suggest climate mitigation opportunities from improved fertilizer management. Global Change Biology, 22(10), 3383–3394. Link to source: https://doi.org/10.1111/gcb.13341

Gerber, J. S., Ray, D. K., Makowski, D., Butler, E. E., Mueller, N. D., West, P. C., Johnson, J. A., Polasky, S., Samberg, L. H., & Siebert, S. (2024). Global spatially explicit yield gap time trends reveal regions at risk of future crop yield stagnation. Nature Food, 5(2), 125–135. Link to source: https://doi.org/10.1038/s43016-023-00913-8 

Gong, C., Tian, H., Liao, H., Pan, N., Pan, S., Ito, A., Jain, A. K., Kou-Giesbrecht, S., Joos, F., Sun, Q., Shi, H., Vuichard, N., Zhu, Q., Peng, C., Maggi, F., Tang, F. H. M., & Zaehle, S. (2024). Global net climate effects of anthropogenic reactive nitrogen. Nature, 632(8025), 557–563. Link to source: https://doi.org/10.1038/s41586-024-07714-4

Gu, B., Zhang, X., Lam, S. K., Yu, Y., van Grinsven, H. J. M., Zhang, S., Wang, X., Bodirsky, B. L., Wang, S., Duan, J., Ren, C., Bouwman, L., de Vries, W., Xu, J., Sutton, M. A., & Chen, D. (2023). Cost-effective mitigation of nitrogen pollution from global croplands. Nature, 613(7942), 77–84. Link to source: https://doi.org/10.1038/s41586-022-05481-8

Hergoualc’h, K., Akiyama, H., Bernoux, M., Chirinda, N., del Prado, A., Kasimir, Å., MacDonald, J. D., Ogle, S. M., Regina, K., & van der Weerden, T. J. (2019). Chapter 11: nitrous oxide Emissions from managed soils, and CO2 emissions from lime and urea application (2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories). Intergovernmental Panel on Climate Change. https://www.ipcc-nggip.iges.or.jp/public/2019rf/pdf/4_Volume4/19R_V4_Ch11_Soils_nitrous oxide_CO2.pdf

Hergoualc’h, K., Mueller, N., Bernoux, M., Kasimir, Ä., van der Weerden, T. J., & Ogle, S. M. (2021). Improved accuracy and reduced uncertainty in greenhouse gas inventories by refining the IPCC emission factor for direct nitrous oxide emissions from nitrogen inputs to managed soils. Global Change Biology, 27(24), 6536–6550. Link to source: https://doi.org/10.1111/gcb.15884

IPCC, 2019. Summary for Policymakers. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems [P.R. Shukla, J. Skea, E. Calvo Buendia, V. Masson-Delmotte, H.-O. Pörtner, D. C. Roberts, P. Zhai, R. Slade, S. Connors, R. van Diemen, M. Ferrat, E. Haughey, S. Luz, S. Neogi, M. Pathak, J. Petzold, J. Portugal Pereira, P. Vyas, E. Huntley, K. Kissick, M. Belkacemi, J. Malley, (eds.)].

Lam, S. K., Suter, H., Mosier, A. R., & Chen, D. (2017). Using nitrification inhibitors to mitigate agricultural nitrous oxide emission: A double-edged sword? Global Change Biology, 23(2), 485–489. Link to source: https://doi.org/10.1111/gcb.13338

Lawrence, N. C., Tenesaca, C. G., VanLoocke, A., & Hall, S. J. (2021). Nitrous oxide emissions from agricultural soils challenge climate sustainability in the US Corn Belt. Proceedings of the National Academy of Sciences, 118(46), e2112108118. Link to source: https://doi.org/10.1073/pnas.2112108118

Ludemann, C. I., Wanner, N., Chivenge, P., Dobermann, A., Einarsson, R., Grassini, P., Gruere, A., Jackson, K., Lassaletta, L., Maggi, F., Obli-Laryea, G., van Ittersum, M. K., Vishwakarma, S., Zhang, X., & Tubiello, F. N. (2024). A global FAOSTAT reference database of cropland nutrient budgets and nutrient use efficiency (1961–2020): Nitrogen, phosphorus and potassium. Earth System Science Data, 16(1), 525–541. Link to source: https://doi.org/10.5194/essd-16-525-2024

Menegat, S., Ledo, A., & Tirado, R. (2022). Greenhouse gas emissions from global production and use of nitrogen synthetic fertilisers in agriculture. Scientific Reports, 12(1), 14490. Link to source: https://doi.org/10.1038/s41598-022-18773-w

Michaelowa, A., Hermwille, L., Obergassel, W., & Butzengeiger, S. (2019). Additionality revisited: Guarding the integrity of market mechanisms under the Paris Agreement. Climate Policy, 19(10), 1211–1224. Link to source: https://doi.org/10.1080/14693062.2019.1628695

Mueller, N. D., Gerber, J. S., Johnston, M., Ray, D. K., Ramankutty, N., & Foley, J. A. (2012). Closing yield gaps through nutrient and water management. Nature, 490(7419), Article 7419. Link to source: https://doi.org/10.1038/nature11420

Patel, N., Srivastav, A. L., Patel, A., Singh, A., Singh, S. K., Chaudhary, V. K., Singh, P. K., & Bhunia, B. (2022). Nitrate contamination in water resources, human health risks and its remediation through adsorption: A focused review. Environmental Science and Pollution Research, 29(46), 69137–69152. Link to source: https://doi.org/10.1007/s11356-022-22377-2

Pinder, R. W., Davidson, E. A., Goodale, C. L., Greaver, T. L., Herrick, J. D., & Liu, L. (2012). Climate change impacts of US reactive nitrogen. Proceedings of the National Academy of Sciences, 109(20), 7671–7675. Link to source: https://doi.org/10.1073/pnas.1114243109

Porter, E. M., Bowman, W. D., Clark, C. M., Compton, J. E., Pardo, L. H., & Soong, J. L. (2013). Interactive effects of anthropogenic nitrogen enrichment and climate change on terrestrial and aquatic biodiversity. Biogeochemistry, 114(1), 93–120. Link to source: https://doi.org/10.1007/s10533-012-9803-3

Qiao, C., Liu, L., Hu, S., Compton, J. E., Greaver, T. L., & Li, Q. (2015). How inhibiting nitrification affects nitrogen cycle and reduces environmental impacts of anthropogenic nitrogen input. Global Change Biology, 21(3), 1249–1257. Link to source: https://doi.org/10.1111/gcb.12802

Qin, Z., Deng, S., Dunn, J., Smith, P., & Sun, W. (2021). Animal waste use and implications to agricultural greenhouse gas emissions in the United States. Environmental Research Letters, 16(6), 064079. Link to source: https://doi.org/10.1088/1748-9326/ac04d7

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Rockström, J., Williams, J., Daily, G., Noble, A., Matthews, N., Gordon, L., Wetterstrand, H., DeClerck, F., Shah, M., Steduto, P., de Fraiture, C., Hatibu, N., Unver, O., Bird, J., Sibanda, L., & Smith, J. (2017). Sustainable intensification of agriculture for human prosperity and global sustainability. Ambio, 46(1), 4–17. Link to source: https://doi.org/10.1007/s13280-016-0793-6

Rurinda, J., Zingore, S., Jibrin, J. M., Balemi, T., Masuki, K., Andersson, J. A., Pampolino, M. F., Mohammed, I., Mutegi, J., Kamara, A. Y., Vanlauwe, B., & Craufurd, P. Q. (2020). Science-based decision support for formulating crop fertilizer recommendations in sub-Saharan Africa. Agricultural Systems, 180, 102790. Link to source: https://doi.org/10.1016/j.agsy.2020.102790

Scavia, D., David Allan, J., Arend, K. K., Bartell, S., Beletsky, D., Bosch, N. S., Brandt, S. B., Briland, R. D., Daloğlu, I., DePinto, J. V., Dolan, D. M., Evans, M. A., Farmer, T. M., Goto, D., Han, H., Höök, T. O., Knight, R., Ludsin, S. A., Mason, D., … Zhou, Y. (2014). Assessing and addressing the re-eutrophication of Lake Erie: Central basin hypoxia. Journal of Great Lakes Research, 40(2), 226–246. Link to source: https://doi.org/10.1016/j.jglr.2014.02.004

Selim, M. M. (2020). Introduction to the integrated nutrient management strategies and their contribution to yield and soil properties. International Journal of Agronomy, 2020(1), 2821678. https://doi.org/10.1155/2020/2821678

Shcherbak, I., Millar, N., & Robertson, G. P. (2014). Global metaanalysis of the nonlinear response of soil nitrous oxide (nitrous oxide) emissions to fertilizer nitrogen. Proceedings of the National Academy of Sciences, 111(25), 9199–9204. Link to source: https://doi.org/10.1073/pnas.1322434111

Shindell, D. T., Faluvegi, G., Koch, D. M., Schmidt, G. A., Unger, N., & Bauer, S. E. (2009). Improved attribution of climate forcing to emissions. Science, 326(5953), 716–718. Link to source: https://doi.org/10.1126/science.1174760

Sobota, D. J., Compton, J. E., McCrackin, M. L., & Singh, S. (2015). Cost of reactive nitrogen release from human activities to the environment in the United States. Environmental Research Letters, 10(2), 025006. Link to source: https://doi.org/10.1088/1748-9326/10/2/025006

Tian, H., Xu, R., Canadell, J. G., Thompson, R. L., Winiwarter, W., Suntharalingam, P., Davidson, E. A., Ciais, P., Jackson, R. B., Janssens-Maenhout, G., Prather, M. J., Regnier, P., Pan, N., Pan, S., Peters, G. P., Shi, H., Tubiello, F. N., Zaehle, S., Zhou, F., … Yao, Y. (2020). A comprehensive quantification of global nitrous oxide sources and sinks. Nature, 586(7828), 248–256. Link to source: https://doi.org/10.1038/s41586-020-2780-0

van Grinsven, H. J. M., Bouwman, L., Cassman, K. G., van Es, H. M., McCrackin, M. L., & Beusen, A. H. W. (2015). Losses of ammonia and nitrate from agriculture and their effect on nitrogen recovery in the European Union and the United States between 1900 and 2050. Journal of Environmental Quality, 44(2), 356–367. Link to source: https://doi.org/10.2134/jeq2014.03.0102

Vanlauwe, B., Descheemaeker, K., Giller, K. E., Huising, J., Merckx, R., Nziguheba, G., Wendt, J., & Zingore, S. (2015). Integrated soil fertility management in sub-Saharan Africa: Unravelling local adaptation. SOIL, 1(1), 491–508. Link to source: https://doi.org/10.5194/soil-1-491-2015

Wang, C., Shen, Y., Fang, X., Xiao, S., Liu, G., Wang, L., Gu, B., Zhou, F., Chen, D., Tian, H., Ciais, P., Zou, J., & Liu, S. (2024). Reducing soil nitrogen losses from fertilizer use in global maize and wheat production. Nature Geoscience, 17(10), 1008–1015. Link to source: https://doi.org/10.1038/s41561-024-01542-x

Wang, Y., Li, C., Li, Y., Zhu, L., Liu, S., Yan, L., Feng, G., & Gao, Q. (2020). Agronomic and environmental benefits of Nutrient Expert on maize and rice in Northeast China. Environmental Science and Pollution Research, 27(22), 28053–28065. Link to source: https://doi.org/10.1007/s11356-020-09153-w

Ward, M. H., Jones, R. R., Brender, J. D., de Kok, T. M., Weyer, P. J., Nolan, B. T., Villanueva, C. M., & van Breda, S. G. (2018). Drinking water nitrate and human health: an updated review. International Journal of Environmental Research and Public Health, 15(7), 1557. Link to source: https://doi.org/10.3390/ijerph15071557

Withers, P. J. A., Neal, C., Jarvie, H. P., & Doody, D. G. (2014). Agriculture and eutrophication: where do we go from here? Sustainability, 6(9), Article 9. Link to source: https://doi.org/10.3390/su6095853

You, L., Ros, G. H., Chen, Y., Shao, Q., Young, M. D., Zhang, F., & de Vries, W. (2023). Global mean nitrogen recovery efficiency in croplands can be enhanced by optimal nutrient, crop and soil management practices. Nature Communications, 14(1), 5747. Link to source: https://doi.org/10.1038/s41467-023-41504-2

Zaehle, S., Ciais, P., Friend, A. D., & Prieur, V. (2011). Carbon benefits of anthropogenic reactive nitrogen offset by nitrous oxide emissions. Nature Geoscience, 4(9), 601–605. Link to source: https://doi.org/10.1038/ngeo1207

Zhang, X., Fang, Q., Zhang, T., Ma, W., Velthof, G. L., Hou, Y., Oenema, O., & Zhang, F. (2020). Benefits and trade-offs of replacing synthetic fertilizers by animal manures in crop production in China: A meta-analysis. Global Change Biology, 26(2), 888–900. Link to source: https://doi.org/10.1111/gcb.14826

Credits

Lead Fellow

  • Avery Driscoll

Contributors

  • Ruthie Burrows, Ph.D.

  • James Gerber, Ph.D.

  • Yusuf Jameel, Ph.D.

  • Daniel Jasper

  • Alex Sweeney

  • Eric Toensmeier

Internal Reviewers

  • Aiyana Bodi

  • Hannah Henkin

  • Ted Otte

Effectiveness

We relied on the 2019 Intergovernmental Panel on Climate Change (IPCC) emissions factors to calculate the emissions impacts of improved nutrient management. These are disaggregated by climate zone (“wet” vs. “dry”) and by fertilizer type (“organic” vs. “synthetic”). Nitrogen use reductions in wet climates, which include ~65% of the cropland area represented in this analysis (see Appendix for details), have the largest impact. In these areas, a 1 t reduction in nitrogen use reduces emissions by 8.7 t CO₂‑eq on average for synthetic fertilizers and by 5.0 t CO₂‑eq for organic fertilizers. Emissions savings are lower in dry climates, where a 1 t reduction in nitrogen use reduces emissions by 2.4 t CO₂‑eq for synthetic fertilizers and by 2.6 t CO₂‑eq for organic fertilizers. While these values reflect the median emissions reduction for each climate zone and fertilizer type, they are associated with large uncertainties because emissions are highly variable depending on climate, soil, and management conditions. 

Based on our analysis of the adoption ceiling for each climate zone and fertilizer type (see Appendix), we estimated that a 1 t reduction in nitrogen use reduces emissions by 6.0 t CO₂‑eq at the global median (Table 1). This suggests that ~1.4% of the applied nitrogen is emitted as nitrous oxide at the global average, which is consistent with existing estimates (IPCC, 2019). 

Table 1. Effectiveness at reducing emissions.

Unit: t CO₂‑eq /t nitrogen, 100-yr basis

25th percentile 4.2
Median (50th percentile) 6.0
75th percentile 7.7
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Cost

Improving nutrient management typically reduces fertilizer costs while maintaining or increasing yields, resulting in a net financial benefit to the producer. Gu et al. (2023) found that a 21% reduction in global nitrogen use would be economically beneficial, notably after accounting for increased fertilizer use in places that do not currently have adequate access. Using data from their study, we evaluated the average cost of reduced nitrogen application considering the following nutrient management practices: increased use of high-efficiency fertilizers, organic fertilizers, and/or legumes; optimizing fertilizer rates; altering the timing and/or placement of fertilizer applications; and use of buffer zones. Implementation costs depend on the strategy used to improve nutrient management. For example, optimizing fertilizer rates requires soil testing and the ability to apply different fertilizer rates to different parts of a field. Improving timing can involve applying fertilizers at two different times during the season, increasing labor and equipment operation costs. Furthermore, planting legumes incurs seed purchase and planting costs. 

Gu et al. (2023) estimated that annual reductions of 42 Mt of nitrogen were achievable globally using these practices, providing total fertilizer savings of US$37.2 billion and requiring implementation costs of US$15.9 billion, adjusted for inflation to 2023. A 1 t reduction in excess nitrogen application, therefore, was estimated to provide an average of US$507.80 of net cost savings, corresponding to a savings of US$85.21 per t CO₂‑eq of emissions reductions (Table 2).

Table 2. Cost per unit of climate impact, 100-yr basis.

Unit: 2023 US$/t CO₂‑eq

Mean -85.21
Left Text Column Width
Methods and Supporting Data

Methods and Supporting Data

Learning Curve

The improved nutrient management strategies considered for this solution are already well established and widely deployed (Fixen, 2020). Large nitrogen excesses are relatively easy to mitigate through simple management changes with low implementation costs. As nitrogen use efficiency increases, further reductions may require increasingly complex mitigation practices and increasing marginal costs. Therefore, a learning curve was not quantified for this solution.

Speed of Action

Speed of action refers to how quickly a climate solution physically affects the atmosphere after it is deployed. This is different from speed of deployment, which is the pace at which solutions are adopted.

At Project Drawdown, we define the speed of action for each climate solution as emergency brake, gradual, or delayed.

Improve Nutrient Management is a GRADUAL climate solution. It has a steady, linear impact on the atmosphere. The cumulative effect over time builds as a straight line.

Caveats

Emissions reductions from improved nutrient management are permanent, though they may not be additional in all cases.

Permanence

As this solution reduces emissions rather than enhancing sequestration, permanence is not applicable.

Additionality

Additionality requires that the emissions benefits of the practice are attributable to climate-related incentives and would not have occurred in the absence of incentives (Michaelowa et al., 2019). If they are not contingent on external incentives, fertilizer use reductions implemented solely to maximize profits do not meet the threshold for additionality. However, fertilizer reductions may be additional if incentives are required to provide access to the technical knowledge and soil testing required to identify optimal rates. Other forms of nutrient management (e.g., applying nitrification inhibitors, using extended-release or organic fertilizers, or splitting applications between two time points) may involve additional costs, substantial practice change, and technical expertise. Thus, these practices are likely to be additional.

Current Adoption

Given that improved nutrient management takes a variety of forms and data on the adoption of individual practices are very limited, we leveraged several global datasets related to nitrogen use and yields to directly assess improvements in nitrogen use efficiency (see Appendix for details).

First, we calculated nitrogen use per metric ton of crop produced using global maps of nitrogen fertilizer use (Adalibieke et al., 2023) and global maps of crop yields (Gerber et al., 2024) for 17 major crops (see Appendix). Next, we determined a target nitrogen use rate (t nitrogen/t crop) for each crop, corresponding to the 20th percentile of nitrogen use rates observed in croplands with yield gaps at or below the 20th percentile, meaning that actual yields were close to an attainable yield ceiling (Gerber et al., 2024). Areas with large yield gaps were excluded from the calculation of target nutrient use efficiency because insufficient nitrogen supply may be compromising yields (Mueller et al., 2012). Yield data were not available for a small number of crops; for these, we assumed reductions in nitrogen use to be proportional to those of other crops.

We considered croplands that had achieved the target rate and had yield gaps lower than the global median to have adopted the solution. We calculated the amount of excess nitrogen use avoided from these croplands as the difference in total nitrogen use under current fertilization rates relative to median fertilizer application rates. As of 2020, croplands that had achieved the adoption threshold for improved nutrient management avoided 10.45 Mt of nitrogen annually relative to the median nitrogen use rate (Table 3), equivalent to 11% of the adoption ceiling.

Table 3. Current (2020) adoption level.

Unit: t nitrogen/yr

Estimate 10,450,000
Left Text Column Width
Adoption Trend

Global average nitrogen use efficiency increased from 47.7% to 54.6% between 2000 and 2020, a rate of approximately 0.43%/yr (Ludemann et al., 2024). This increase accelerated somewhat in the latter decade, from an average rate of 0.38%/yr to 0.53%/yr. Underlying this increase were increases in both the amount of nitrogen used and the amount of excess nitrogen. Total nitrogen additions increased by approximately 2.64 Mt/yr, with the amount of nitrogen used increasing more rapidly (1.99 Mt/yr) than the amount of excess nitrogen (0.65 Mt/yr) between 2000 and 2020 (Ludemann et al., 2024). Although nitrogen use increased between 2000 and 2020 as yields increased, the increase in nitrogen use efficiency suggests uptake of this solution.

Adoption Ceiling

We estimated the adoption ceiling of improved nutrient management to be 95.13 Mt avoided excess nitrogen use/year, not including current adoption (Table 4). This value reflects our estimate of the maximum potential reduction in nitrogen application while avoiding large yield losses and consists of the potential to avoid 62.25 Mt of synthetic nitrogen use and 32.88 Mt of manure and other organic nitrogen use, in addition to current adoption. In total, this is equivalent to an additional 68% reduction in global nitrogen use. The adoption ceiling was calculated as the difference between total nitrogen use at the current rate and total nitrogen use at the target rate (as described in Current Adoption), assuming no change in crop yields. For nitrogen applied to crops for which yield data were not available, the potential reduction in nitrogen use was assumed to be proportional to that of crops for which full data were available.

Table 4. Adoption ceiling.

Unit: t nitrogen/yr

Estimate 105,580,000
Left Text Column Width
Achievable Adoption

We estimated that fertilizer use reductions of 69.85–91.06 Mt of nitrogen are achievable, reflecting current adoption plus nitrogen savings due to the achievement of nitrogen application rates equal to the median and 30th percentile of nitrogen application rates occurring in locations where yield gaps are small (Table 5).

This range is more ambitious than a comparable recent estimate by Gu et al. (2023), who found that reductions of approximately 42 Mt of nitrogen are avoidable via cost-effective implementation of similar practices. Differences in target nitrogen use efficiencies underlie differences between our estimates and those of Gu et al., whose findings correspond to an increase in global average cropland nitrogen use efficiency from 42% to 52%. Our estimates reflect higher target nitrogen use efficiencies. Nitrogen use efficiencies greater than 52% have been widely achieved through basic practice modification without compromising yields or requiring prohibitively expensive additional inputs. For instance, You et al. (2023) estimated that the global average nitrogen use efficiency could be increased to 78%. Similarly, cropland nitrogen use efficiency in the United States in 2020 was estimated to be 71%, and substantial opportunities for improved nitrogen use efficiency are still available within the United States (Ludemann et al., 2024), though Lu et al. (2019) and Swaney et al. (2018) report slightly lower estimates. These findings support our slightly more ambitious range of achievable nitrogen use reductions for this solution.

Table 5. Range of achievable adoption levels.

Unit: t nitrogen/yr

Current adoption 10,450,000
Achievable – low 69,850,000
Achievable – high 91,060,000
Adoption ceiling 105,580,000
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We estimated that improved nutrient management has the potential to reduce emissions by 0.63 Gt CO₂‑eq/yr, with achievable emissions reductions of 0.42–0.54 Gt CO₂‑eq/yr (Table 6). This is equivalent to an additional 56–76% reduction in total nitrous oxide emissions from fertilizer use, based on the croplands represented in our analysis.

We estimated avoidable emissions by multiplying our estimates of adoption ceiling and achievable adoption by the relevant IPCC 2019 emissions factors, disaggregated by climate zone and fertilizer type. Under the adoption ceiling scenario, approximately 70% of emissions reductions occurred in wet climates, where emissions per t of applied fertilizer are higher. Reductions in synthetic fertilizer use, which are larger than reductions in organic fertilizer use, contributed about 76% of the potential avoidable emissions. We estimated that the current implementation of improved nutrient management was associated with 0.06 Gt CO₂‑eq/yr of avoided emissions. 

Our estimates are slightly more optimistic but well within the range of the IPCC 2021 estimates, which found that improved nutrient management could reduce nitrous oxide emissions by 0.06–0.7 Gt CO₂‑eq/yr.

Table 6. Climate impact at different levels of adoption.

Unit: Gt CO₂-eq/yr, 100-yr basis

Current adoption 0.06
Achievable – low 0.42
Achievable – high 0.54
Adoption ceiling 0.63
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Additional Benefits

Droughts

Balanced nutrient concentration contributes to long-term soil fertility and improved soil health by enhancing organic matter content, microbial diversity, and nutrient cycling (Antil & Raj, 2020; Selim, 2020). Healthy soil experiences reduced erosion and has higher water content, which increases its resilience to droughts and extreme heat (Rockström et al., 2017).

Income and Work

Better nutrient management reduces farmers' input costs and increases profitability (Rurinda et al., 2020; Wang et al., 2020). It is especially beneficial to smallholder farmers in sub-Saharan Africa, where site-specific nutrient management programs have demonstrated a significant increase in yield (Chivenge et al., 2021). A review of 61 studies across 11 countries showed that site-specific nutrient management resulted in an average increase in yield by 12% and increased farmer’s’ income by 15% while improving nitrogen use efficiency (Chivenge et al., 2021). 

Food Security

While excessive nutrients cause environmental problems in some parts of the world, insufficient nutrients are a significant problem in others, resulting in lower agricultural yields (Foley et al., 2011). Targeted, site-specific, efficient use of fertilizers can improve crop productivity (Mueller et al., 2012; Vanlauwe et al., 2015), improving food security globally. 

Health

Domingo et al. (2021) estimated about 16,000 premature deaths annually in the United States are due to air pollution from the food sector and found that more than 3,500 premature deaths per year could be avoided through reduced use of ammonia fertilizer, a secondary particulate matter precursor. Better agriculture practices overall can reduce particulate matter-related premature deaths from the agriculture sector by 50% (Domingo et al., 2021). Nitrogen oxides from fertilized croplands are another source of agriculture-based air pollution, and improved management can lead to decreased respiratory and cardiovascular disease (Almarez et al., 2018; Sobota et al., 2015). 

Nitrate contamination of drinking water due to excessive runoff from agriculture fields has been linked to several health issues, including blood disorders and cancer (Patel et al., 2022; Ward et al., 2018). Reducing nutrient runoff through better management is critical to minimize these risks (Ward et al., 2018). 

Nature Protection

Nutrient runoff from agricultural systems is a major driver of water pollution globally, leading to eutrophication and hypoxic zones in aquatic ecosystems (Bijay-Singh & Craswell, 2021). Nitrogen pollution also harms terrestrial biodiversity through soil acidification and increases productivity of fast-growing species, including invasives, which can outcompete native species (Porter et al., 2013). Improved nutrient management is necessary to reduce nitrogen and phosphorus loads to water bodies (Withers et al., 2014; van Grinsven et al., 2019) and terrestrial ecosystems (Porter et al., 2013). These practices have been effective in reducing harmful algal blooms and preserving biodiversity in sensitive water systems (Scavia et al., 2014). 

Risks

Although substantial reductions in nitrogen use can be achieved in many places with no or minimal impacts on yields, reducing nitrogen application by too much can lead to yield declines, which in turn can boost demand for cropland, causing GHG-producing land use change. Reductions in only excess nitrogen application will prevent substantial yield losses.

Some nutrient management practices are associated with additional emissions. For example, nitrification inhibitors reduce direct nitrous oxide emissions (Qiao et al., 2014) but can increase ammonia volatilization and subsequent indirect nitrous oxide emissions (Lam et al., 2016). Additionally, in wet climates, nitrous oxide emissions may be reduced through the use of manure instead of synthetic fertilizers (Hergoualc’h et al., 2019), though impacts vary across sites and studies (Zhang et al., 2020). Increased demand for manure could increase livestock production, which has high associated GHG emissions. Emissions also arise from transporting manure to the site of use (Qin et al., 2021).

Although nitrous oxide has a strong direct climate-warming effect, fertilizer use can cool the climate through emissions of other reactive nitrogen-containing compounds (Gong et al., 2024). First, aerosols from fertilizers scatter heat from the sun and cool the climate (Shindell et al., 2009; Gong et al., 2024). Moreover, other reactive nitrogen compounds from fertilizers shorten the lifespan of methane in the atmosphere, reducing its warming effects (Pinder et al., 2012). Finally, nitrogen fertilizers that leave farm fields through volatilization or runoff are ultimately deposited elsewhere, enhancing photosynthesis and storing more carbon in plants and soils (Zaehle et al., 2011; Gong et al., 2024). Improved nutrient management would reduce these cooling effects.

Interactions with Other Solutions

Reinforcing

Improved nutrient management will reduce emissions from the production phase of biomass crops, increasing their benefit.

(mixed) Improving nutrient management can reduce nutrient pollution in nearby and downstream ecosystems, aiding in their protection or restoration. However, this interaction can be mixed as fertilizer can also enhance terrestrial primary productivity and carbon sequestration in some landscapes.

Competing

Improved nutrient management will reduce the GHG production associated with each calorie and, therefore, the impacts of the Improve Diets and Reduce Food Loss and Waste solutions will be reduced. 

Each of these solutions could decrease emissions associated with fertilizer production, but improved nutrient management will reduce total demand for fertilizers.

Dashboard

Solution Basics

t avoided excess nitrogen application

t CO₂-eq (100-yr)/unit
04.26median
units/yr
Current 1.045×10⁷ 06.985×10⁷9.106×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.06 0.420.54
US$ per t CO₂-eq
-85
Gradual

N₂O

t CO2-eq/ha/yr
01

The problem: nitrous oxide emissions from over-fertilized soils

The world’s agricultural lands can emit high levels of nitrous oxide, the third most powerful greenhouse gas. These emissions stem from overusing nitrogen-based fertilizers, especially in regions in China, India, Western Europe, and central North America (in red). While crops absorb some of the nitrogen fertilizer we apply, much of what remains is lost to the atmosphere as nitrous oxide pollution or to local waterways as nitrate pollution. Using fertilizers more wisely can dramatically reduce greenhouse gas emissions and water pollution while maintaining high levels of crop production.

Project Drawdown

t CO2-eq/ha/yr
01

The problem: nitrous oxide emissions from over-fertilized soils

The world’s agricultural lands can emit high levels of nitrous oxide, the third most powerful greenhouse gas. These emissions stem from overusing nitrogen-based fertilizers, especially in regions in China, India, Western Europe, and central North America (in red). While crops absorb some of the nitrogen fertilizer we apply, much of what remains is lost to the atmosphere as nitrous oxide pollution or to local waterways as nitrate pollution. Using fertilizers more wisely can dramatically reduce greenhouse gas emissions and water pollution while maintaining high levels of crop production.

Project Drawdown

Maps Introduction

Improved nutrient management will have the greatest emissions reduction if it is targeted at areas with the largest excesses of nitrogen fertilizer use. In 2020, China, India, and the United States alone accounted for 52% of global excess nitrogen application (Ludemann et al., 2024). Improved nutrient management could be particularly beneficial in China and India, where nutrient use efficiency is currently lower than average (Ludemann et al., 2024). You et al. (2023) also found potential for large increases in nitrogen use efficiency in parts of China, India, Australia, Northern Europe, the United States Midwest, Mexico, and Brazil under standard best management practices. Gu et al. (2024) found that nitrogen input reductions are economically feasible in most of Southern Asia, Northern and Western Europe, parts of the Middle East, North America, and Oceania.

In addition to regional patterns in the adoption ceiling, greater nitrous oxide emissions reductions are possible in wet climates or on irrigated croplands compared to dry climates. Nitrous oxide emissions tend to peak when nitrogen availability is high and soil moisture is in the ~70–90% range (Betterbach-Bahl et al., 2013; Elberling et al., 2023; Hao et al., 2025; Lawrence et al., 2021), though untangling the drivers of nitrous oxide emissions is complex (Lawrence et al., 2021). Water management to avoid prolonged periods of soil moisture in this range is an important complement to nutrient management in wet climates and on irrigated croplands (Deng et al., 2018).

Importantly, improved nutrient management, as defined here, is not appropriate for implementation in areas with nitrogen deficits or negligible nitrogen surpluses, including much of Africa. In these areas, crop yields are constrained by nitrogen availability, and an increase in nutrient inputs may be needed to achieve target yields. Additionally, nutrient management in paddy (flooded) rice systems is not included in this solution but rather in the Improve Rice Production solution.

Action Word
Improve
Solution Title
Nutrient Management
Classification
Highly Recommended
Lawmakers and Policymakers
  • Focus policies and regulations on the four nutrient management principles – right rate, type, time, and place.
  • Create dynamic nutrient management policies that account for varying practices, environments, drainage, historical land use, and other factors that may require adjusting nutrient regulations.
  • Offer financial assistance responsive to local soil and weather conditions, such as grants and subsidies, insurance programs, and tax breaks, to encourage farmers to comply with regulations.
  • Mandate insurance schemes that allow farmers to reduce fertilizer use.
  • Mandate nutrient budgets or ceilings that are responsive to local yield, weather, and soil conditions.
  • Require farmers to formulate nutrient management and fertilizer plans.
  • Mandate efficiency rates for manure-spreading equipment.
  • Ensure access to and require soil tests to inform fertilizer application.
  • Invest in research on alternative organic nutrient sources.
  • Create and expand education programs and extension services that highlight the problems that arise from the overuse of fertilizers, benefits of soil management such as cost-savings, and penalties for non-compliance
  • Create ongoing support groups among farmers.

Further information:

Practitioners
  • Use the four nutrient management principles – right rate, type, time, and place – to guide fertilizer application.
  • Utilize or advocate for financial assistance and tax breaks for farmers to improve nutrient management techniques.
  • Create and adhere to nutrient and fertilizer management plans.
  • Conduct soil tests to inform fertilizer application.
  • Use winter cover crops, crop rotations, residue retention, and split applications for fertilizer.
  • Improve the efficiency of, and regularly calibrate, manure-spreading equipment.
  • Leverage agroecological practices such as nutrient recycling and biological nitrogen fixation.
  • Join, create, or participate in partnerships or certification programs dedicated to improving nutrient management.
  • Take advantage of education programs, support groups, and extension services focused on improved nutrient management.

Further information:

Business Leaders
  • Provide incentives for farmers in primary sourcing regions to adopt best management practices for reducing nitrogen application.
  • Invest in companies that use improved nutrient management techniques or produce equipment or research for fertilizer application and testing.
  • Advocate to policymakers for improved nutrient management techniques, incentives, and regulations.
  • Join, create, or participate in partnerships or certification programs dedicated to improving nutrient management practices.
  • Promote products produced with improved nutrient management techniques and educate consumers about the importance of the practice.
  • Create or support education programs and extension services that highlight the problems that arise from the overuse of fertilizers, benefits of soil management such as cost-savings, and penalties for non-compliance.
  • Create ongoing support groups among farmers.

Further information:

Nonprofit Leaders
  • Start model farms to demonstrate improved nutrient management techniques, conduct experiments, and educate local farmers.
  • Conduct and share research on improved nutrient management techniques, alternative organic fertilizers, or local policy options.
  • Advocate to policymakers for improved nutrient management techniques, incentives, and regulations.
  • Engage with businesses to encourage corporate responsibility and/or monitor water quality and soil health.
  • Join, create, or participate in partnerships or certification programs dedicated to improving nutrient management practices.
  • Create or support education programs and extension services that highlight the problems that arise from the overuse of fertilizers, benefits of soil management such as cost-savings, and penalties for non-compliance.
  • Create ongoing support groups among farmers.

Further information:

Investors
  • Invest in companies developing technologies that support improved nutrient management such as precision fertilizer applicators, alternative fertilizers, soil management equipment, and software.
  • Invest in ETFs and ESG funds that hold companies committed to improved nutrient management techniques in their portfolios.
  • Encourage companies in your investment portfolio to adopt improved nutrient management.
  • Provide access to capital at reduced rates for farmers adhering to improved nutrient management.

Further information:

Philanthropists and International Aid Agencies
  • Provide financing for farmers to improve nutrient management.
  • Start model farms to demonstrate nutrient management techniques, conduct experiments, and educate local farmers.
  • Conduct and share research on improved nutrient management, alternative organic fertilizers, or local policy options.
  • Advocate to policymakers for improved nutrient management techniques, incentives, and regulations.
  • Engage with businesses to encourage corporate responsibility and/or monitor water quality and soil health.
  • Join, create, or participate in partnerships or certification programs dedicated to improving nutrient management practices.
  • Create or support education programs and extension services that highlight the problems that arise from the overuse of fertilizers, benefits of soil management such as cost-savings, and penalties for non-compliance.
  • Create ongoing support groups among farmers.

Further information:

Thought Leaders
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Conduct and share research on improved nutrient management, alternative organic fertilizers, or local policy options.
  • Advocate to policymakers for improved nutrient management techniques, incentives, and regulations.
  • Engage with businesses to encourage corporate responsibility and/or monitor water quality and soil health.
  • Join, create, or participate in partnerships dedicated to improving nutrient management practices.
  • Create or support education programs and extension services that highlight the problems that arise from the overuse of fertilizers, benefits of soil management such as cost-savings, and penalties for non-compliance.
  • Create ongoing support groups among farmers.

Further information:

Technologists and Researchers
  • Improve technology and cost-effectiveness of precision fertilizer application, slow-release fertilizer, alternative organic fertilizers, nutrient recycling, and monitoring equipment.
  • Create tracking and monitoring software to support farmers' decision-making.
  • Research and develop the application of AI and robotics for precise fertilizer application.
  • Improve data and analytics to monitor soil and water quality, assist farmers, support policymaking, and assess the impacts of policies.
  • Develop education and training applications to promote improved nutrient management and provide real-time feedback.

Further information:

Communities, Households, and Individuals
  • Create or join community-supported agriculture programs that source from farmers who used improved nutrient management practices.
  • Conduct soil tests on your lawn and garden and reduce fertilizer use if you are over-fertilizing.
  • Volunteer for soil and water quality monitoring and restoration projects.
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Advocate to policymakers for improved nutrient management techniques, incentives, and regulations.
  • Engage with businesses to encourage corporate responsibility and/or monitor water quality and soil health.
  • Join, create, or participate in partnerships dedicated to improving nutrient management.
  • Create or support education programs and extension services that highlight the problems that arise from the overuse of fertilizers, benefits of soil management such as cost-savings, and penalties for non-compliance.
  • Create ongoing support groups among farmers.

Further information:

Sources
Evidence Base

Consensus of effectiveness in reducing nitrous oxide emissions from croplands: High

There is high scientific consensus that reducing nitrogen surpluses through improved nutrient management reduces nitrous oxide emissions from croplands. 

Nutrient additions to croplands produce an estimated 0.9 Gt CO₂‑eq/yr (range 0.7–1.1 Gt CO₂‑eq/yr ) of direct nitrous oxide emissions from fields, plus approximately 0.3 Gt CO₂‑eq/yr of emissions from fertilizers that runoff into waterways or erode (Tian et al., 2020). Nitrous oxide emissions from croplands are directly linked to the amount of nitrogen applied. Furthermore, the amount of nitrous oxide emitted per unit of applied nitrogen is well quantified for a range of different nitrogen sources and field conditions (Reay et al., 2012; Shcherbak et al., 2014; Gerber et al., 2016; Intergovernmental Panel on Climate Change [IPCC], 2019; Hergoualc’h et al., 2021). Tools to improve nutrient management have been extensively studied, and practices that improve nitrogen use efficiency through right rate, time, place, and type principles have been implemented in some places for several decades (Fixen, 2020; Ludemann et al., 2024).

Recently, Gao & Cabrera Serrenho (2023) estimated that fertilizer-related emissions could be reduced up to 80% by 2050 relative to current levels using a combination of nutrient management and new fertilizer production methods. You et al. (2023) found that adopting improved nutrient management practices would increase nitrogen use efficiency from a global average of 48% to 78%, substantially reducing excess nitrogen. Wang et al. (2024) estimated that the use of enhanced-efficiency fertilizers could reduce nitrogen losses to the environment 70–75% for maize and wheat systems. Chivenge et al. (2021) found comparable results in smallholder systems in Africa and Asia.

The results presented in this document were produced through analysis of global datasets. We recognize that geographic biases can influence the development of global datasets and hope this work inspires research and data sharing on this topic in underrepresented regions.

Appendix

In this analysis, we calculated the potential for reducing crop nitrogen inputs and associated nitrous oxide emissions by integrating spatially explicit, crop-specific data on nitrogen inputs, crop yields, attainable yields, irrigated extent, and climate. Broadly, we calculated a “target” yield-scaled nitrogen input rate based on pixels with low yield gaps and calculated the difference between nitrous oxide emissions under the current rate and under the hypothetical target emissions rate, using nitrous oxide emissions factors disaggregated by fertilizer type and climate. 

Emissions Factors

We used Tier 1 emissions factors from the IPCC 2019 Refinement to the 2006 Guidelines for National Greenhouse Gas Inventories, including direct emissions factors as well as indirect emissions from volatilization and leaching pathways. Direct emissions factors represent the proportion of applied nitrogen emitted as nitrous oxide, while we calculated volatilization and leaching emissions factors by multiplying the proportion of applied nitrogen lost through these pathways by the proportion of volatilized or leached nitrogen ultimately emitted as nitrous oxide. Including both direct and indirect emissions, organic and synthetic fertilizers emit 4.97 kg CO₂‑eq/kg nitrogen and 8.66 kg CO₂‑eq/kg nitrogen, respectively, in wet climates, and 2.59 kg CO₂‑eq/kg nitrogen and 2.38 kg CO₂‑eq/kg nitrogen in dry climates. We included uncertainty bounds (2.5th and 97.5th percentiles) for all emissions factors. 

We classified each pixel as “wet” or “dry” using an aridity index (AI) threshold of 0.65, calculated as the ratio of annual precipitation to potential evapotranspiration (PET) from TerraClimate data (1991–2020), based on a threshold of 0.65. For pixels in dry climates that contained irrigation, we took the weighted average of wet and dry emissions factors based on the fraction of cropland that was irrigated (Mehta et al., 2024). We excluded irrigated rice from this analysis due to large differences in nitrous oxide dynamics in flooded rice systems.

Current, Target, and Avoidable Nitrogen Inputs and Emissions

Using highly disaggregated data on nitrogen inputs from Adalibieke et al. (2024) for 21 crop groups (Table S1), we calculated total crop-specific inputs of synthetic and organic nitrogen. We then averaged over 2016–2020 to reduce the influence of interannual variability in factors like fertilizer prices. These values are subsequently referred to as “current” nitrogen inputs. We calculated nitrous oxide emissions under current nitrogen inputs as the sum of the products of nitrogen inputs and the climatically relevant emissions factors for each fertilizer type.

Next, we calculated target nitrogen application rates in terms of kg nitrogen per ton of crop yield using data on actual and attainable yields for 17 crops from Gerber et al., 2024 (Table S1). For each crop, we first identified pixels in which the ratio of actual to attainable yields was above the 80th percentile globally. The target nitrogen application rate was then calculated as the 20th percentile of nitrogen application rates across low-yield-gap pixels. Finally, we calculated total target nitrogen inputs as the product of actual yields and target nitrogen input rates. We calculated hypothetical nitrous oxide emissions from target nitrogen inputs as the product of nitrogen inputs and the climatically relevant emissions factor for each fertilizer type.

The difference between current and target nitrogen inputs represents the amount by which nitrogen inputs could hypothetically be reduced without compromising crop productivity (i.e., “avoidable” nitrogen inputs). We calculated avoidable nitrous oxide emissions as the difference between nitrous oxide emissions with current nitrogen inputs and those with target nitrogen inputs. For crops for which no yield or attainable yield data were available, we applied the average percent reduction in nitrogen inputs under the target scenario from available crops to the nitrogen input data for missing crops to calculate the avoidable nitrogen inputs and emissions. 

This simple and empirically driven method aimed to identify realistically low but nutritionally adequate nitrogen application rates by including only pixels with low yield gaps, which are unlikely to be substantially nutrient-constrained. We did not control for other factors affecting nitrogen availability, such as historical nutrient application rates or depletion, rotation with nitrogen fixing crops, or tillage and residue retention practices.

Table S1. Crops represented by the source data on nitrogen inputs (Adalibieke et al., 2024) and estimated and attainable yields (Gerber et al., 2024). Crop groups included consistently in both datasets are marked as “both,” and crop groups represented in the nitrogen input data but not in the yield datasets are marked as “nitrogen only.”

Crop Dataset(s)
BarleyBoth
CassavaBoth
CottonBoth
MaizeBoth
MilletBoth
Oil palmBoth
PotatoBoth
RiceBoth
RyeBoth
RapeseedBoth
SorghumBoth
SoybeanBoth
SugarbeetBoth
SugarcaneBoth
SunflowerBoth
Sweet potatoBoth
WheatBoth
GroundnutNitrogen only
FruitsNitrogen only
VegetablesNitrogen only
OtherNitrogen only
Left Text Column Width
Updated Date

Improve Forest Management

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions
Cluster
Protect & Manage Ecosystems
Image
Foresters with laptop computer in forest
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Description for Social and Search
The Improve Forest Management solution is coming soon.
Methods and Supporting Data

Methods and Supporting Data

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Action Word
Improve
Solution Title
Forest Management
Classification
Highly Recommended
Updated Date

Protect Seafloors

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean (FALO)
Mode
Cut Emissions and Remove Carbon
Cluster
Protect & Manage Ecosystems
Image
An image of a seafloor featuring two pinkish-orange anemones
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Summary

Protect Seafloors is the long-term protection of the seafloor from degradation, which helps preserve existing sediment carbon stocks and avoid CO₂ emissions. Advantages of seafloor protection include the conservation of biodiversity and marine ecosystems, potentially low costs, and the ability for immediate implementation. Disadvantages include uncertainties in the effectiveness of legal protection at preventing degradation and in the amount of CO₂ emissions avoided, as well as the risk of displacement of degradation to non-protected areas and/or an increase in other types of degradation. Given these limitations, we conclude that Seafloor Protection is a climate solution to “Keep Watching” until more research can clearly show the carbon benefits of protection.

Description for Social and Search
Protect Seafloors is the long-term protection of the seafloor from degradation, which helps preserve existing sediment carbon stocks and avoid CO₂ emissions. Advantages of seafloor protection include the conservation of biodiversity and marine ecosystems, potentially low costs, and the ability for immediate implementation.
Overview

What is our assessment?

Based on our analysis, seafloor protection could avoid some CO₂ emissions while preserving critical marine ecosystems from degradation. However, the effectiveness of protection and the magnitude of avoided CO₂ emissions associated with protection are understudied and currently unclear. Therefore, we will “Keep Watching” this potential climate solution.

Plausible Could it work? Yes
Ready Is it ready? No
Evidence Are there data to evaluate it? Limited
Effective Does it consistently work? No
Impact Is it big enough to matter? Yes
Risk Is it risky or harmful? No
Cost Is it cheap? Yes

What is it?

Protect Seafloors aims to reduce human impacts that can degrade sediment carbon stocks and increase CO₂ emissions. Protection is conferred through legal mechanisms, such as Marine Protected Areas (MPAs), which are managed with the primary goal of conserving nature. The seafloor stores over 2,300 Gt of carbon (roughly 8,400 Gt CO₂‑eq) in the top one meter of sediment. This marine carbon can be stable and remain sequestered for millennia. However, degradation of the seafloor from a range of human activities can disturb bottom sediments, resuspending the carbon and increasing its microbial conversion into CO₂. Currently, degradation of the seafloor primarily results from fishing practices, such as trawling and dredging, which are estimated to occur across 1.3% of the global ocean. Additional sources of degradation include undersea mining, infrastructure development (for offshore wind farms, oil, and gas), and laying telecommunications cables. Estimates of seafloor degradation are highly uncertain due to data limitations and the unpredictable nature of how these activities may expand in the future.

Does it work?

More evidence is needed to confirm whether legal seafloor protection is effective at reducing degradation and the extent to which degradation results in increased CO₂ emissions. While ~8% of the seafloor is currently protected through MPAs, there is mixed evidence that legal protection reduces degradation and CO₂ emissions. For instance, in a review of 49 studies examining the impacts of bottom trawling and dredging on sediment organic carbon stocks, most (61%) showed no change, while nearly a third (29%) showed carbon loss. More recent work suggests that trawling intensity might drive these mixed results, with more heavily trawled areas showing clear reductions in sediment organic carbon. Additionally, the few existing global estimates of CO₂ emissions from trawling and dredging range from 0.03 to 0.58 Gt CO₂/yr, highlighting the need for further research. The effectiveness of MPAs at preventing seafloor degradation is also mixed. In strictly protected areas with enforcement of no-take policies that prevent bottom fishing, MPAs could help minimize degradation and retain seafloor carbon. However, implementation can be challenging, as over half of existing MPAs generally allow high-impact activities. For instance, trawling and dredging occur more frequently in MPAs than in non-protected areas in the territorial waters of Europe.

Why are we excited?

Advantages of seafloor protection include its potential low cost and its ability to conserve often understudied biodiversity and ecosystems.  Human activities, such as trawling and dredging, impact marine organisms on the seafloor, and ecosystem recovery can take years to occur. In the case of undersea mining, ecosystems may never fully recover. Increases in CO₂ emissions along the seafloor from degradation can also enhance local acidification and reduce the ocean's buffering capacity, both of which can affect marine organisms and the carbon sequestration capacity of seawater. Protection can also increase fisheries yields in neighboring waters and reduce other negative impacts of seafloor disturbances. While costs are somewhat uncertain, MPA expenses have been estimated to be an order of magnitude less than the often unseen ecosystem service benefits gained with protection, suggesting MPA expansion could provide cost savings.

Why are we concerned?

Disadvantages of seafloor protection include uncertainties surrounding the effectiveness of preventing degradation and avoiding CO₂ emissions, as well as the potential increased risk of disturbance to other ocean areas. The amount and fate of CO₂ generated due to the degradation of seafloor carbon is complex and understudied. It can take months or even centuries for CO₂ produced at depth to reach the sea surface and atmosphere. Current estimates of CO₂ emissions due to dredging and trawling are widely debated and highly variable due to differing methods and assumptions. Large amounts of organic carbon will inevitably re-settle after seafloor disturbances, with no impact on CO₂, but estimates of just how much remain uncertain. The risk of protection-induced leakage, where a reduction in disturbances, such as trawling and dredging in MPAs, leads to increased fishing effort in other ocean areas, is also potentially high.

Amoroso, R. O., Pitcher, C. R., Rijnsdorp, A. D., McConnaughey, R. A., Parma, A. M., Suuronen, P., ... & Jennings, S. (2018). Bottom trawl fishing footprints on the world’s continental shelves. Proceedings of the National Academy of Sciences, 115(43), E10275-E10282. Link to source: https://doi.org/10.1073/pnas.1802379115

Atwood, T. B., Witt, A., Mayorga, J., Hammill, E., & Sala, E. (2020). Global patterns in marine sediment carbon stocks. Frontiers in Marine Science, 7, 165. Link to source: https://doi.org/10.3389/fmars.2020.00165 

Atwood, T.B., Sala, E., Mayorga, J. et al. Reply to: Quantifying the carbon benefits of ending bottom trawling. Nature, 617, E3–E5 (2023). Link to source: https://doi.org/10.1038/s41586-023-06015-6 

Atwood, T. B., Romanou, A., DeVries, T., Lerner, P. E., Mayorga, J. S., Bradley, D., ... & Sala, E. (2024). Atmospheric CO2 emissions and ocean acidification from bottom-trawling. Frontiers in Marine Science, 10, 1125137. Link to source: https://doi.org/10.3389/fmars.2023.1125137 

Balmford, A., Gravestock, P., Hockley, N., McClean, C.J. and Roberts, C.M. (2004). The worldwide costs of marine protected areas. Proceedings of the National Academy of Sciences, 101(26), pp.9694-9697. Link to source: https://doi.org/10.1073/pnas.0403239101 

Burdige, D. J. (2005). Burial of terrestrial organic matter in marine sediments: a re-assessment. Global Biogeochem. Cycles, 19:GB4011. Link to source: https://doi.org/10.1029/2004GB002368 

Burdige, D. J. (2007). Preservation of organic matter in marine sediments: controls, mechanisms, and an imbalance in sediment organic carbon budgets? Chem. Rev., 107, 467–485. Link to source: https://doi.org/10.1021/cr050347q 

Carr, M. E., Friedrichs, M. A. M., Schmeltz, M., Aita, M. N., Antoine, D., Arrigo, K., et al. (2006). A comparison of global estimates of marine primary production from ocean color. Deep-sea Res. II, Top. Stud. Oceanogr., 53, 741–770. Link to source: https://doi.org/10.1016/j.dsr2.2006.01.028 

Clare, M. A., Lichtschlag, A., Paradis, S., & Barlow, N. L. M. (2023). Assessing the impact of the global subsea telecommunications network on sedimentary organic carbon stocks. Nature Communications, 14(1), 2080. Link to source: https://doi.org/10.1038/s41467-023-37854-6 

Dureuil, M., Boerder, K., Burnett, K. A., Froese, R., & Worm, B. (2018). Elevated trawling inside protected areas undermines conservation outcomes in a global fishing hot spot. Science, 362(6421), 1403-1407. Link to source: https://doi.org/10.1126/science.aau0561 

Epstein, G., Middelburg, J. J., Hawkins, J. P., Norris, C. R., & Roberts, C. M. (2022). The impact of mobile demersal fishing on carbon storage in seabed sediments. Global Change Biology, 28(9), 2875-2894. Link to source: https://doi.org/10.1111/gcb.16105 

Estes, E. R., Pockalny, R., D’Hondt, S., Inagaki, F., Morono, Y., Murray, R. W., ... & Hansel, C. M. (2019). Persistent organic matter in oxic subseafloor sediment. Nature Geoscience, 12(2), 126-131. Link to source: https://doi.org/10.1038/s41561-018-0291-5 

Kandasamy, S., & Nagender Nath, B. (2016). Perspectives on the terrestrial organic matter transport and burial along the land-deep sea continuum: caveats in our understanding of biogeochemical processes and future needs. Frontiers in Marine Science, 3, 259. Link to source: https://doi.org/10.3389/fmars.2016.00259 

Muller-Karger, F. E., Varela, R., Thunell, R., Luerssen, R., Hu, C., and Walsh, J. J. (2005). The importance of continental margins in the global carbon cycle. Geophys. Res. Lett., 32:L01602. Link to source: https://doi.org/10.1029/2004gl021346 

Putuhena, H., White, D., Gourvenec, S., & Sturt, F. (2023). Finding space for offshore wind to support net zero: A methodology to assess spatial constraints and future scenarios, illustrated by a UK case study. Renewable and Sustainable Energy Reviews, 182, 113358. Link to source: https://doi.org/10.1016/j.rser.2023.113358 

Sala, E., Mayorga, J., Bradley, D., Cabral, R. B., Atwood, T. B., Auber, A., ... & Lubchenco, J. (2021). Protecting the global ocean for biodiversity, food and climate. Nature, 592(7854), 397-402. Link to source: https://doi.org/10.1038/s41586-021-03371-z 

Sala, E., & Giakoumi, S. (2018). No-take marine reserves are the most effective protected areas in the ocean. ICES Journal of Marine Science, 75(3), 1166-1168. Link to source: https://doi.org/10.1093/icesjms/fsx059 

Siegel, D. A., DeVries, T., Doney, S. C., & Bell, T. (2021). Assessing the sequestration time scales of some ocean-based carbon dioxide reduction strategies. Environmental Research Letters, 16(10), 104003. Link to source: https://doi.org/10.1088/1748-9326/ac0be0 

(TMC, 2022) The Metals Company. (2022). How much seafloor will the nodule collection industry impact? Retrieved April 17, 2025, from Link to source: https://metals.co/how-much-seafloor-will-the-nodule-collection-industry-impact/ 

UNEP-WCMC and IUCN (2024). Protected Planet Report 2024. UNEP-WCMC and IUCN: Cambridge, United Kingdom; Gland, Switzerland. Link to source: https://digitalreport.protectedplanet.net/ 

Zhang, W., Porz, L., Yilmaz, R., Wallmann, K., Spiegel, T., Neumann, A., ... & Schrum, C. (2024). Long-term carbon storage in shelf sea sediments reduced by intensive bottom trawling. Nature Geoscience, 1-9. Link to source: https://doi.org/10.1038/s41561-024-01581-4 

van de Velde, S. J., Hylén, A., & Meysman, F. J. (2025). Ocean alkalinity destruction by anthropogenic seafloor disturbances generates a hidden CO2 emission. Science Advances, 11(13).Link to source: https://doi.org/10.1126/sciadv.adp9112 

Watson, S. C., Somerfield, P. J., Lemasson, A. J., Knights, A. M., Edwards-Jones, A., Nunes, J., ... & Beaumont, N. J. (2024). The global impact of offshore wind farms on ecosystem services. Ocean & Coastal Management, 249, 107023. Link to source: https://doi.org/10.1016/j.ocecoaman.2024.107023 

Credits

Lead Fellow

  • Christina Richardson, Ph.D.

Internal Reviewer

  • Christina Swanson, Ph.D.
Action Word
Protect
Solution Title
Seafloors
Classification
Keep Watching
Updated Date

Protect Coastal Wetlands

Submitted by Drawdown Admin on
Sector
FALO & Nature-Based Carbon Removal
Mode
Cut Emissions
Cluster
Protect & Manage Ecosystems
Image
Birds flying over wetland
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Off
Summary

Coastal wetland protection is the long-term protection of mangrove, salt marsh, and seagrass ecosystems from degradation by human activities. This solution focuses on legal mechanisms of coastal wetland protection, including the establishment of Protected Areas (PAs) and Marine Protected Areas (MPAs), which are managed with the primary goal of conserving nature. These legal protections reduce a range of human impacts, helping to preserve existing carbon stocks and avoid CO₂ emissions.

Extreme weather events
Income & work,Food security,Equality
Nature protection,Land resources,Water quality
Description for Social and Search
Protect Coastal Wetlands is a Highly Recommended climate solution. Legal protection helps these ecosystems store carbon and avoids GHG emissions.
Overview

Coastal wetlands (defined as mangrove, salt marsh, and seagrass ecosystems, see Figure 1) are highly productive ecosystems that sequester carbon via photosynthesis, storing it primarily below ground in sediments where waterlogged, low-oxygen conditions help preserve it (Adame et al., 2024; Lovelock et al., 2017). 

Figure 1. Types of coastal wetlands, from left to right: a salt marsh in Westhampton Beach (United States), a mangrove forest near Staniel Cay (Bahamas), and a seagrass meadow off Notojima Island (Japan).

Types of wetlands

Adobe Stock | istock; Maria T Hoffman | Adobe Stock; James White and Danita Delimont | AdobeStock

These ecosystems are also efficient at trapping carbon suspended in water, which can comprise up to 50% of the carbon sequestered in these settings (McLeod et al., 2011; Temmink et al., 2022). Coastal wetlands operate as large carbon sinks (Figure 2), with long-term carbon accumulation rates averaging 5.1–8.3 t CO₂‑eq /ha/yr (McLeod et al., 2011).

Figure 2. Overview of carbon storage in coastal wetlands. Salt marshes, mangroves, and seagrasses, commonly referred to as blue carbon ecosystems, store carbon in plant biomass and sediment.

Diagram demonstr ating CO2 absorption in salt marsh, mangroves, and seagrass.

Source: Macreadie, P. I., Costa, M. D., Atwood, T. B., Friess, D. A., Kelleway, J. J., Kennedy, H., ... & Duarte, C. M. (2021). Blue carbon as a natural climate solution. Nature Reviews Earth & Environment, 2(12), 826-839. Link to source: https://doi.org/10.1038/s43017-021-00224-1

Protection of coastal wetlands preserves carbon stocks and avoids emissions associated with degradation, which can increase CO₂, methane, and nitrous oxide effluxes. Nearly 50% of the total global area of coastal wetlands has been lost since 1900 and up to 87% since the 18th century (Davidson, 2014). With current loss rates, an additional 30–40% of remaining seagrasses and salt marshes, and nearly all mangroves, could be lost by 2100 without protection (Pendleton et al., 2012). Protection of existing coastal wetlands is especially important because restoration is challenging, costly, and not yet fully optimized. For example, seagrass restoration has generally been unsuccessful (Macreadie et al., 2021), and restored seagrass systems can have higher GHG fluxes than natural systems (Mason et al., 2023).

On land, degradation often arises from aquaculture, reclamation and drainage, deforestation, diking, and urbanization (Mcleod et al., 2011). In the ocean, impacts often occur due to dredging, mooring, pollution, and sediment disturbance (Mcleod et al., 2011). For instance, deforestation of mangroves for agriculture removes biomass and oxidizes sediment carbon stocks, leading to high CO₂ effluxes and, potentially, methane and nitrous oxide emissions (Chauhan et al., 2017, Kauffman et al., 2016, Sasmito et al., 2019). Likewise, high CO₂ or methane effluxes from salt marshes commonly result from drainage, which can oxygenate the subsurface and fuel carbon loss, or from infrastructure such as dikes, which can reduce saltwater exchange and increase methane production (Kroeger et al., 2017). In another example, dredging in seagrass meadows drives high rates of ecosystem degradation due to reduced light availability, leading to die-offs that can increase erosion and reduce sediment carbon stocks by 21–47% (Trevathan-Tackett et al., 2018).

Our analysis focused on the avoided CO₂ emissions and retained carbon sequestration capacity conferred by avoiding degradation of coastal wetlands via legal protection. While degradation can substantially alter emissions of other GHGs, such as methane and nitrous oxide, we focus on CO₂ due to the limited availability of global spatial data on degradation types and extent and associated effluxes of all GHGs across coastal wetlands. Ignoring methane and nitrous oxide benefits with protection is the most conservative approach because limited data exist on emission profiles from both functional and degraded global coastal wetlands, and even PAs/MPAs can be degraded (Holmquist et al., 2023). This solution considered wetlands to be protected if they are formally designated as PAs or MPAs under International Union for Conservation of Nature (IUCN) protection categories I–IV (UNEP-WCMC &IUCN, 2024; see Appendix for more information).

Adame, M. F., Kelleway, J., Krauss, K. W., Lovelock, C. E., Adams, J. B., Trevathan-Tackett, S. M., Noe, G., Jeffrey, L., Ronan, M., Zann, M., Carnell, P. E., Iram, N., Maher, D. T., Murdiyarso, D., Sasmito, S., Tran, D. B., Dargusch, P., Kauffman, J. B., & Brophy, L. (2024). All tidal wetlands are blue carbon ecosystems. BioScience, 74(4), 253–268. Link to source: https://doi.org/10.1093/biosci/biae007

Balmford, A., Gravestock, P., Hockley, N., McClean, C. J., & Roberts, C. M. (2004). The worldwide costs of marine protected areas. Proceedings of the National Academy of Sciences, 101(26), 9694–9697. Link to source: https://doi.org/10.1073/pnas.0403239101

Baniewicz, T. (2020, September 2). Coastal Louisiana tribes team up with biologist to protect sacred sites from rising seas. Southerly. Link to source: https://southerlymag.org/2020/09/02/coastal-louisiana-tribes-team-up-with-biologist-to-protect-sacred-sites-from-rising-seas/

Barbier, E. B., Georgiou, I. Y., Enchelmeyer, B., & Reed, D. J. (2013). The value of wetlands in protecting southeast Louisiana from hurricane storm surges. PLoS ONE, 8(3), Article e58715. Link to source: https://doi.org/10.1371/journal.pone.0058715

Blanchard, L., Haya, B. K., Anderson, C., Badgley, G., Cullenward, D., Gao, P., Goulden, M. L., Holm, J. A., Novick, K. A., Trugman, A. T., Wang, J. A., Williams, C. A., Wu, C., Yang, L., & Anderegg, W. R. L. (2024). Funding forests’ climate potential without carbon offsets. One Earth, 7(7), 1147–1150. Link to source: https://doi.org/10.1016/j.oneear.2024.06.006

Borchert, S. M., Osland, M. J., Enwright, N. M., & Griffith, K. T. (2018). Coastal wetland adaptation to sea level rise: Quantifying potential for landward migration and coastal squeeze. Journal of Applied Ecology, 55(6), 2876–2887. Link to source: https://doi.org/10.1111/1365-2664.13169

Bruner, A. G., Gullison, R. E., & Balmford, A. (2004). Financial costs and shortfalls of managing and expanding protected-area systems in developing countries. BioScience, 54(12), 1119–1126. Link to source: https://doi.org/10.1641/0006-3568(2004)054[1119:FCASOM]2.0.CO;2

Chauhan, R., Datta, A., Ramanathan, A. L., & Adhya, T. K. (2017). Whether conversion of mangrove forest to rice cropland is environmentally and economically viable? Agriculture, Ecosystems & Environment, 246, 38–47. Link to source: https://doi.org/10.1016/j.agee.2017.05.010

Cullen-Unsworth, L. C., & Unsworth, R. (2018). A call for seagrass protection. Science, 361(6401), 446–448. Link to source: https://doi.org/10.1126/science.aat7318

Department of Climate Change, Energy, the Environment and Water. (2016). Wetlands and Indigenous values [Fact sheet]. Commonwealth of Australia. Link to source: https://www.dcceew.gov.au/sites/default/files/documents/factsheet-wetlands-indigenous-values.pdf

Dabalà, A., Dahdouh-Guebas, F., Dunn, D. C., Everett, J. D., Lovelock, C. E., Hanson, J. O., Buenafe, K. C. V., Neubert, S., & Richardson, A. J. (2023). Priority areas to protect mangroves and maximise ecosystem services. Nature Communications, 14(1), Article 5863. Link to source: https://doi.org/10.1038/s41467-023-41333-3

Davidson, N. C. (2014). How much wetland has the world lost? Long-term and recent trends in global wetland area. Marine and Freshwater Research, 65(10), 934–941. Link to source: https://doi.org/10.1071/MF14173

Di Minin, E., & Toivonen, T. (2015). Global protected area expansion: Creating more than paper parks. BioScience, 65(7), 637–638. Link to source: https://doi.org/10.1093/biosci/biv064

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Credits

Lead Fellow

  • Christina Richardson, Ph.D.

Contributors

  • Ruthie Burrows, Ph.D.

  • Avery Driscoll

  • James Gerber, Ph.D.

  • Daniel Jasper

  • Christina Swanson, Ph.D.

  • Alex Sweeney

  • Paul West, Ph.D.

Internal Reviewers

  • Aiyana Bodi

  • Avery Driscoll

  • James Gerber, Ph.D.

  • Hannah Henkin

  • Ted Otte

  • Christina Swanson, Ph.D.

Effectiveness

We estimated that coastal wetland protection avoids emissions of 2.33–5.74 t CO₂‑eq /ha/yr, while also sequestering an additional 1.22–2.14 t CO₂‑eq /ha/yr depending on the ecosystem (Tables 1a–c; see the Appendix for more information). We estimated effectiveness as the avoided CO₂ emissions and the retained carbon sequestration capacity attributable to the reduction in wetland loss conferred by protection, as detailed in Equation 1. First, we calculated the difference between the rate of wetland loss outside PAs and MPAs (Wetland lossbaseline) versus inside PAs and MPAs, since protection does not entirely prevent degradation. Loss rates were primarily driven by anthropogenic habitat conversion. The effectiveness of protection was 53–59% (Reduction in loss). We then multiplied the avoided wetland loss by the sum of the avoided CO₂ emissions associated with the loss of carbon stored in sediment and biomass in one ha of wetland each year over a 30-yr timeframe (Carbonavoided emissions) and the amount of carbon sequestered via long-term storage in sediment carbon by one ha of protected wetland each year over a 30-yr timeframe (Carbonsequestration).

Equation 1.

\[ Effectiveness = (Wetland\text{ }loss_{baseline}\times Reduction\text{ }in\text{ }loss)\times(Carbon_{avoided\text{ } emissions} + Carbon_{sequestration}) \]

We did this calculation separately for mangrove, salt marsh, and seagrass ecosystems, because many of these factors, such as carbon emission and sequestration rates, protection effectiveness, and loss rates, vary across ecosystem types. The rationale for increasing protection varies between coastal wetland ecosystem types, but in all cases, protection is an important tool for retaining and building long-lived carbon stocks. Additionally, climate impacts associated with this solution could be much greater than estimated if protection efficacy improves or is higher than our estimates of 53–59%. 

Table 1a. Effectiveness at avoiding emissions and sequestering carbon in mangrove ecosystems.

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 5.64
Mean 6.80
Median (50th percentile) 5.74
75th percentile 7.42

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 2.00
Mean 2.14
Median (50th percentile) 2.14
75th percentile 2.38

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 7.64
Mean 8.94
Median (50th percentile) 7.88
75th percentile 9.81
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Table 1b. Effectiveness at avoiding emissions and sequestering carbon in salt marsh ecosystems.

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis 

25th percentile 2.79
Mean 2.90
Median (50th percentile) 2.90
75th percentile 3.01

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 1.59
Mean 1.90
Median (50th percentile) 1.88
75th percentile 2.19

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 4.38
Mean 4.80
Median (50th percentile) 4.78
75th percentile 5.20
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Table 1c. Effectiveness at avoiding emissions and sequestering carbon in seagrass ecosystems.

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 2.11
Mean 2.33
Median (50th percentile) 2.33
75th percentile 2.56

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 1.04
Mean 1.53
Median (50th percentile) 1.22
75th percentile 1.71

Unit: t CO₂‑eq /ha protected/yr, 100-yr basis

25th percentile 3.15
Mean 3.86
Median (50th percentile) 3.56
75th percentile 4.27
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Cost

We estimate that coastal wetland protection costs approximately US$1–2/t CO₂‑eq for mangrove and salt marsh ecosystems and seagrass ecosystem protection saves US$6/t CO₂‑eq (Tables 2a–c). This is based on protection costs of roughly US$11/ha and revenue of US$23/ha compared with the baseline for mangrove/salt marsh and seagrass ecosystems, respectively. However, data related to the costs of coastal wetland protection are extremely limited, and these estimates are uncertain. These estimates likely underestimate the potentially high costs of coastal land acquisition, for instance.

The costs of coastal wetland protection include up-front costs of land acquisition (for salt marshes and mangroves) and other one-time expenditures as well as ongoing operational costs. Protecting coastal wetlands also generates revenue, primarily through increased tourism. For consistency across solutions, we did not include revenue associated with benefits other than climate change mitigation.

Due to data limitations, we estimated the cost of land acquisition for ecosystem protection for mangroves and salt marshes by extracting coastal forest land purchase costs reported by Dinerstein et al. (2024), who found a median cost of US$1,115/ha (range: US$78–5,910/ha), which we amortized over 30 years. For seagrass ecosystems, which do not generally require land acquisition, we based initial costs were on McCrea-Strub et al.’s (2011) findings that reported a median MPA start-up cost of US$208/ha (range: US$55–434/ha) to cover expenses associated with infrastructure, planning, and site research, which we amortized over 30 years.

Costs of PA maintenance were estimated as US$17/ha/yr (Waldron et al., 2020). While these estimates reflect the costs of effective enforcement and management, many PAs lack sufficient funding for effective management (Bruner et al., 2004). Costs of MPA maintenance were estimated at US$14/ha/yr, though only 16% of the MPAs surveyed in this study reported their current funding as sufficient (Balmford et al., 2004). Tourism revenues directly attributable to protection were estimated to be US$43/ha/yr (Waldron et al., 2020) based on estimates for all PAs and MPAs and excluding downstream revenues. For consistency across solutions, we did not include revenues associated with ecosystem services, which would increase projected revenue.

We also excluded carbon credits as a revenue source due to the challenges inherent in accurate carbon accounting in these ecosystems and their frequently intended use to offset carbon emissions, similar to reported concerns with low-quality carbon credits in forest conservation projects (West et al., 2023). Future actions could explore policies that increase market financing for coastal wetland protection in more holistic ways, such as contributions-based approaches as suggested for forests (Blanchard et al., 2024). Financial support will be critical for backing conservation implementation (Macreadie et al., 2022), particularly in the face of existing political and economic challenges that have historically limited expansion. 

Table 2. Cost per unit climate impact.

Unit: 2023 US$/t CO₂‑eq , 100-yr basis

Estimate 1

Unit: 2023 US$/t CO₂‑eq , 100-yr basis

Estimate 2

Unit: 2023 US$/t CO₂‑eq , 100-yr basis

Estimate -6

Negative value indicates cost savings.

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Methods and Supporting Data

Methods and Supporting Data

Learning Curve

We define a learning curve as falling costs with increased adoption. The costs of coastal wetland protection do not fall with increasing adoption, so there is no learning curve for this solution.

Speed of Action

Speed of action refers to how quickly a climate solution physically affects the atmosphere after it is deployed. This is different from speed of deployment, which is the pace at which solutions are adopted.

At Project Drawdown, we define the speed of action for each climate solution as emergency brake, gradual, or delayed.

Protect Coastal Wetlands is an EMERGENCY BRAKE climate solution. It has the potential to deliver a more rapid impact than gradual and delayed solutions. Because emergency brake solutions can deliver their climate benefits quickly, they can help accelerate our efforts to address dangerous levels of climate change. For this reason, they are a high priority.

Caveats

Additionality in this solution refers to whether the ecosystem would have been degraded without protection. In this analysis, we assumed protection confers additional carbon benefits as it reduces degradation and associated emissions. Another aspect of additionality, though not directly relevant to our analysis, is whether coastal wetlands would have been protected in the absence of carbon financing. This could become increasingly important if protection efforts seek carbon credits, since many wetlands are protected for other benefits, such as flood resilience and biodiversity.

The permanence of stored carbon in coastal wetlands is another critical issue as climate change impacts unfold. For instance, with sea-level rise, the ability of salt marshes to expand both vertically and laterally can determine resiliency, suggesting that protection of wetlands might also need to include adjacent areas for expansion (Schuerch et al., 2018). On a global scale, recent research suggests that global carbon accumulation might actually increase by 2100 from climate change impacts on tidal wetlands (Wang et al., 2021), though more work is needed as other work suggests the opposite (Noyce et al., 2023). There is also substantial risk of reversal of carbon benefits if protections are reversed or unenforced, which can require long-term financial investments, community engagement, and management/enforcement commitments (Giakoumi et al., 2018), particularly if the land is leased.

Finally, there are significant uncertainties associated with the available data on coastal wetland areas and distributions, loss rates, drivers of loss, extent and boundaries of PAs/MPAs, and efficacy of PAs/MPAs at reducing coastal wetland disturbance. For example, the geospatial datasets we used to identify the adoption ceiling for this solution could include partially degraded systems, such as drained wetlands, where protection alone would not stop emissions or restore function without restoration – yet we lack enough data to distinguish these current differences at a global scale. Similarly, legal protection of coastal wetlands does not always prevent degradation (Heck et al., 2024). The emissions dynamics of both intact and degraded coastal wetlands are also uncertain. Even less is known about the impacts of different types of degradation on coastal wetland carbon dynamics and how they vary spatially and temporally around the world.

Current Adoption

We estimated that approximately 8.04 million ha of coastal wetlands are currently protected, with 5.13 million ha recognized as PAs and MPAs in strict (I–II) protection categories and 2.90 million ha in non-strict protection categories (III–IV) (Tables 3a–c; Garnett et al., 2018; UNEP-WCMC & IUCN, 2024, see Appendix). Indigenous People’s Lands (IPLs) cover an additional 3.44 million ha; we did not include these in our analysis due to limited data, but we recognize that these sites might currently deliver conservation benefits. In total, we estimate that roughly 15% of all coastal wetlands have some protection (as MPAs or PAs in IUCN categories I–IV), though only about 9% are under strict protection (IUCN categories I or II). Across individual ecosystem types, strict protection categories (IUCN I–II) are highest for mangroves (~15%) and lowest for seagrasses (~7%).

Our estimates of PA and MPA protection (12–19%) were lower than previously reported estimates for mangroves (40–43%, Dabalà et al., 2023; Leal and Spalding, 2024), tidal marshes (45%, Worthington et al., 2024), and seagrasses (26%, United Nations Environment Programme [UNEP], 2020). This is likely because our calculations excluded IUCN categories (“not assigned,” “not applicable,” and “not reported”) that contain large areal estimates for each ecosystem type – 4.3 million ha (mangrove), 1.9 million ha (salt marsh), and 5.4 million ha (seagrasses) – because their protection category was unclear as well as IUCN protection categories V–VI, which permit sustainable use and where extractive activities that could degrade these ecosystems are less formally restricted. Our spatial analysis also differed (see Appendix).

Table 3. Current extent of ecosystems under legal protection by ecosystem type (circa 2023). “Strict Protection” includes land within IUCN Categories I–II PAs or MPAs. “Nonstrict Protection” includes land within IUCN Categories III–IV PAs or MPAs. “Other” includes land within all remaining IUCN PA or MPA categories.

Unit: million ha protected

Strict protection 2.35
Nonstrict protection 0.59
Total (strict + nonstrict) 2.94
IPL 1.86
Other 7.52

Unit: million ha protected

Strict protection 0.62
Nonstrict protection 0.62
Total (strict + nonstrict) 1.24
IPL 1.09
Other 3.14

Unit: million ha protected

Strict protection 2.17
Nonstrict protection 1.69
Total (strict + nonstrict) 3.86
IPL 0.49
Other 9.00
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Adoption Trend

We calculated the rate of PA and MPA expansion based on their recorded year of establishment. Protection expanded by an average of 59,600, 19,700, and 98,500 ha/yr in mangrove, salt marsh, and seagrass ecosystems, respectively (Tables 4a–c; Figure 3a). Salt marsh ecosystems have the lowest absolute rate of coastal wetland protection expansion (Figure 3b), while seagrasses have the lowest expansion of PAs relative to their adoption ceiling (Figure 3, right). The median total annual adoption trend across the three ecosystems is roughly 123,100 ha/yr (roughly 0.12 million ha/yr).

Table 4. 2000–2020 adoption trend for legal protection of ecosystems.

Unit: ha/yr protected

25th percentile 23,500
Mean 59,600
Median (50th percentile) 40,700
75th percentile 76,600

Unit: ha/yr protected

25th percentile 8,400
Mean 19,700
Median (50th percentile) 18,500
75th percentile 23,300

Unit: ha/yr protected

25th percentile 12,800
Mean 98,500
Median (50th percentile) 37,800
75th percentile 142,900
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Figure 3. (a) Areal trend in coastal wetland protection by ecosystem type (2000–2020). These values reflect only the area located within IUCN Class I–IV PAs or MPAs; (ha/yr protected). (b) Trend in coastal wetland protection by ecosystem type as a percent of the adoption ceiling. These values reflect only the area located within IUCN Class I–IV PAs or MPAs; (Percent). Source: Project Drawdown original analysis.

Credit: Project Drawdown

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Adoption Ceiling

We estimate an adoption ceiling of 54.6 million ha of coastal wetlands globally, which includes 15.7 million ha of mangroves, 7.50 million ha of salt marshes, and 31.4 million ha of seagrasses (Tables 5a–c). This estimate is in line with recent existing global estimates of coastal wetlands (36–185 million ha), which have large ranges due to uncertainties surrounding seagrass and salt marsh distributions (Macreadie et al., 2021, Krause et al., 2025). The adoption ceiling of our solution is therefore a conservative estimate of potential climate impact if global areas are indeed larger than calculated. While the protection of all existing coastal wetlands is highly unlikely, these values are used to represent the technical limits of adoption of this solution.

Table 5. Adoption ceiling: upper limit for adoption of legal protection of ecosystems.

Unit: million ha protected

Estimate 15.7

Unit: million ha protected

Estimate 7.50

Unit: million ha protected

Estimate 31.4
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Achievable Adoption

We defined the lower end of the achievable range for coastal wetland protection (under IUCN categories I–IV) as 50% of the adoption ceiling and the higher end of the achievable range as 70% of the adoption ceiling for each ecosystem (Tables 6a–c). These numbers are ambitious but precedent exists to support them. For instance, roughly 11 countries already protect over 70% of their mangroves (Dabalà et al., 2023), and the global “30 by 30” target aims to protect 30% of ecosystems on land and in the ocean by 2030 (Roberts et al., 2020). Further, a significant extent of existing global coastal wetland areas already fall under non-strict protection categories not included in our analysis (V–VI and “Other”). These are prime candidates for conversion to stricter protection categories, so long as the designation confers real conservation benefits; recent work suggests that stricter protection can coincide with increased degradation in some mangroves (Heck et al., 2024).

Current adoption of PAs and MPAs in many countries with the highest land areas of coastal wetlands is low. For example, protection levels (IUCN I–IV) in countries with the top 10 greatest mangrove areas ranges between less than 1% (India, Myanmar, Nigeria, and Papua New Guinea) to 8.8–21.2% (Australia, Bangladesh, Brazil, Indonesia, Malaysia, and Mexico;Dabalà et al., 2023). Expansion of PAs, particularly under IUCN I–IV categories, is a significant challenge with real implementation barriers due to competing land uses and local reliance on these areas for livelihoods. Further, protection does not guarantee conservation benefits, and significant funding is required to maintain/enforce these areas or they run the risk of becoming “paper parks” (Di Minin & Toivonen, 2015). Strong policy and financial incentives for conservation will be necessary to achieve these ambitious goals. Pathways for operationalizing protection could include finance, governance, and stakeholder alignment and will likely require a combination of these tactics around the world. 

Table 6. Range of achievable adoption levels for ecosystems.

Unit: million ha protected

Current adoption 2.94
Achievable – low 7.85
Achievable – high 11.0
Adoption ceiling 15.7

Unit: million ha protected

Current adoption 1.24
Achievable – low 3.75
Achievable – high 5.25
Adoption ceiling 7.50

Unit: million ha protected

Current adoption 3.86
Achievable – low 15.7
Achievable – high 22.0
Adoption ceiling 31.4
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We estimated that coastal wetland protection currently avoids approximately 0.04 Gt CO₂‑eq/yr, with potential impacts of 0.27 Gt CO₂‑eq/yr at the adoption ceiling (Table 7a–c, see Appendix for more information on the calculations). The lower-end achievable scenario (50% protection) would avoid 0.14 Gt CO₂‑eq/yr, and the upper-end achievable scenario (70% protection) would avoid 0.20 Gt CO₂‑eq/yr (Tables 7a–c). These values are in line with Macreadie et al. (2021), who estimated a maximum mitigation potential from avoided emissions due to degradation (land conversion) of 0.30 (range: 0.14–0.47) Gt CO₂‑eq/yr for mangrove, salt marsh, and seagrass ecosystems. Our estimate was slightly lower, but within their range, and differed in a few key ways. We accounted for the effectiveness of protection at reducing degradation (53–59%, instead of assuming 100%), included retained carbon sequestration with each hectare protected, and used slightly different loss rates and ecosystem areas.

Table 7. Climate impact at different levels of adoption for ecosystems.

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current adoption 0.02
Achievable – low 0.06
Achievable – high 0.09
Adoption ceiling 0.12

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current adoption 0.01
Achievable – low 0.02
Achievable – high 0.03
Adoption ceiling 0.04

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current adoption 0.01
Achievable – low 0.06
Achievable – high 0.08
Adoption ceiling 0.11
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Additional Benefits

Extreme Weather Events

Wetlands buffer coastal communities from waves and storm surge due to extreme weather and have important roles in disaster risk mitigation (Sheng et al., 2022; Guannel et al., 2016). Mangroves slow the flow of water and reduce surface waves to protect more than 60 million people in low-lying coastal areas, mainly in low- and middle-income countries (McIvor et al., 2012; Hochard et al., 2021). Wetlands also protect structures against damage during storms and lead to savings in insurance claims (Barbier et al., 2013; Sheng et al., 2022). Mangroves provide an estimated US$65 billion in flood protection globally (Menéndez et al., 2020). A study of the damages of Hurricane Sandy found that wetlands in the northeastern United States avoided US$625 million in direct flood damages (Narayan et al., 2017).

Income and Work

Wetlands are a contributor to local livelihoods, providing employment for coastal populations via the fisheries and tourism that they support. Coastal ecosystems, such as mangroves, are crucial for subsistence fisheries as they sustain approximately 4.1 million small-scale fishers (Leal and Spalding, 2022). Wetlands provide sources of income for low-income coastal communities as they make small-scale fishing accessible, requiring limited gear and materials to fish (Cullen-Unsworth & Unsworth, 2018). The economic value of mangrove ecosystem services is estimated at US$33,000–57,000/ha/yr and is a major contributor to the national economies of low- and middle-income countries with mangroves (UNEP, 2014).

Food Security

Mangroves support the development of numerous commercially important fish species and strengthen overall fishery productivity. For example, research conducted across 6,000 villages in Indonesia found that rural coastal households near high and medium-density mangroves consumed more fish and aquatic animals than households without mangroves nearby (Ickowitz et al., 2023). Seagrasses also support fisheries as 20% of the world’s largest fisheries rely on seagrasses for habitats (Jensen, 2022). The amount and diversity of species within seagrasses also provide important nutrition for fishery species (Cullen-Unsworth & Unsworth, 2018).

Equality

Coastal wetlands are significant in cultural heritages and identities for nearby people. They can be associated with historical, religious, and spiritual values for communities and especially for Indigenous communities (UNEP, 2014). For example, a combination of sea-level rise and oil and gas drilling have contributed to the decline of coastal wetlands in Louisiana, which threatens livelihoods and deep spiritual ties of local Indigenous tribes (Baniewicz, 2020; Hutchinson, 2022). Indigenous people have a long history of managing and protecting coastal wetlands (Mathews & Turner, 2017). Efforts to protect these areas must include legal recognition of Indigenous ownership to support a just and sustainable conservation process (Fletcher et al., 2021).

Nature Protection

Coastal wetlands are integral in supporting the biodiversity of surrounding watersheds. High species diversity of mangroves and seagrasses provide a unique habitat for marine life, birds, insects, and mammals, and contain numerous threatened or endangered species (Green and Short, 2003; U.S. EPA, 2025a). A variety of species rely on wetlands for food and shelter, and they can provide temporary habitats for species during critical times in their life cycles, such as migration and breeding (Unsworth et al., 2022). Wetlands can improve water quality, making the surrounding ecosystem more favorable to supporting marine life (Cullen-Unsworth & Unsworth, 2018). Seagrasses can improve coral health by filtering water and reducing pathogens that could cause disease (Cullen-Unsworth & Unsworth, 2018).

Land Resources

Wetlands reduce coastal erosion which can benefit local communities during strong storms (Jensen, 2022). Wetlands mitigate erosion impacts by absorbing wave energy that would degrade sand and other marine sediments (U.S. EPA, 2025b). Specifically, mangroves reduce erosion through their aerial root structure that retain sediments that would otherwise degrade the shoreline (Thampanya et al., 2006).

Water Quality

Coastal wetlands improve the water quality of watersheds by filtering chemicals, particles (including microplastics), sediment, and cycling nutrients (Unsworth et al. 2022). There is even evidence that wetlands can remove viruses and bacteria from water, leading to better sanitation and health for marine wildlife and humans (Lamb et al., 2017).

Risks

There are several risks associated with coastal wetland protection. Leakage, wherein protection in one region could prompt degradation of another, could reduce climate benefits (Renwick et al., 2015). Strict conservation of coastal wetlands could impact local economies, creating “poverty traps” if protection threatens livelihoods (McNally et al., 2011). Conservation projects also risk unequal distribution of benefits (Lang et al., 2023). In places where habitats are fragmented or existing infrastructure limits landward migration, even protected coastal wetlands are at risk of being lost with climate change (commonly known as “the coastal squeeze”; Borchert et al., 2018). Funding gaps risk reversal of climate benefits despite initial conservation efforts; most MPAs and PAs report a lack of funding (Balmford et al., 2004; Bruner et al., 2004). If coastal wetlands are subjected to human impacts that protection cannot prevent, such as upgradient nutrient pollution, there could also be a risk of increased GHG emissions (Feng et al., 2025) and ecosystem degradation.

Interactions with Other Solutions

Reinforcing

Other ecosystems often occur adjacent to areas of coastal wetlands, and the health of nearby ecosystems can be improved by the services provided by intact coastal wetlands (and vice versa). 

Competing

Mangrove deforestation can occur for fuel wood needs. Fuel wood sourced from mangroves could be replaced with wood sourced from other forested ecosystems.

Protecting coastal wetlands could limit near-shore land availability for renewable energy technologies and competes with the following solution for land:

Dashboard

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
07.647.88median
units
Current 2.94×10⁶ 07.85×10⁶1.1×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.02 0.060.09
US$ per t CO₂-eq
1
Emergency Brake

CO₂

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
04.384.78median
units
Current 1.24×10⁶ 03.75×10⁶5.25×10⁶
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.01 0.020.03
US$ per t CO₂-eq
2
Emergency Brake

CO₂

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
03.153.56median
units
Current 3.86×10⁶ 01.57×10⁷2.2×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.01 0.060.08
US$ per t CO₂-eq
-6
Emergency Brake

CO₂

Trade-offs

Trade-offs associated with protection of coastal wetlands include emission of other GHGs not quantified in this solution that have higher global warming potentials (GWP) than CO₂. Methane and nitrous oxide emissions can be measurable in coastal wetland ecosystems, though it is important to recognize that degradation can significantly impact the magnitude and types of effluxes, too. In mangroves, methane evasion can offset carbon burial by almost 20% based on a 20-yr GWP (Rosentreter et al., 2018). In seagrasses, methane and nitrous oxide effluxes can offset burial on average, globally, by 33.4% based on a 20-yr GWP and 7.0% based on a 100-yr GWP (Eyre et al., 2023). Finally, conservation of coastal land can also restrict development of desirable coastal property for other uses.

% mangroves
> 0100

Global mangrove ecosystem distribution

Mangrove ecosystems cover approximately 15.7 million ha globally; just five countries (Australia, Brazil, Indonesia, Mexico, and Nigeria) contain nearly 50% of the world’s mangrove ecosystem area (FAO, 2020). Green shaded areas indicate the general location of mangrove ecosystems; zoom in for details.

Liu, L., Zhang, X., & Zhao, T. (2022). GWL_FCS30: global 30 m wetland map with fine classification system using multi-sourced and time-series remote sensing imagery in 2020 [Data set, Version 1]. Link to source: https://doi.org/10.5281/zenodo.7340516

% mangroves
> 0100

Global mangrove ecosystem distribution

Mangrove ecosystems cover approximately 15.7 million ha globally; just five countries (Australia, Brazil, Indonesia, Mexico, and Nigeria) contain nearly 50% of the world’s mangrove ecosystem area (FAO, 2020). Green shaded areas indicate the general location of mangrove ecosystems; zoom in for details.

Liu, L., Zhang, X., & Zhao, T. (2022). GWL_FCS30: global 30 m wetland map with fine classification system using multi-sourced and time-series remote sensing imagery in 2020 [Data set, Version 1]. Link to source: https://doi.org/10.5281/zenodo.7340516

Maps Introduction

The current adoption, potential adoption, and effectiveness of coastal wetland protection is ecosystem-dependent (mangroves, salt marshes, seagrasses) and geographically variable. While coastal wetland protection can help avoid GHG emissions anywhere they occur, ecosystems with high rates of loss from human activity, and large unprotected areas have the greatest potential for avoiding emissions via protection. 

For instance, seagrass ecosystems have the lowest current adoption of protection, ~12%, and highest adoption ceiling (31.4 Mha) (Tables 3 and 6). Protecting seagrasses also potentially can save money (–US$23/ha, Table 2) because they do not generally require land purchase (McCrea-Strub et al., 2011). Protection of seagrasses could therefore provide meaningful climate impact as well as substantial economic and ecologic benefits (Unsworth et al., 2022). 

For seagrasses, countries like Australia (~10 Mha), Indonesia (~3 Mha), the United States (~0.5 Mha), and regions such as the Gulf of Mexico (~2 Mha) and the Western Mediterranean (~0.4 Mha), could be good initial targets for protection due to their significant seagrass extents (Green and Short, 2003). Countries that contain the top 10 largest areas of mangroves (Australia, Bangladesh, Brazil, India, Indonesia, Malaysia, Mexico, Myanmar, Nigeria, Papua New Guinea) might have the greatest potential to significantly expand adoption and scale climate impact (Dabalà et al., 2023). Likewise, salt marsh protection might be most beneficial in countries with the greatest extent, such as the United States (~1.7 Mha), Australia (~1.3 Mha), Russia (~0.7 Mha), and China (~0.6 Mha) (Mcowen et al., 2017).

Action Word
Protect
Solution Title
Coastal Wetlands
Classification
Highly Recommended
Lawmakers and Policymakers
  • Grant Indigenous communities full property rights and autonomy; support them in monitoring, managing, and enforcing MPAs/PAs/IPLs.
  • Ensure effective enforcement and monitoring of existing PAs using real-time and satellite data, if available.
  • Create or strengthen legislative protections for coastal wetlands, requiring their consideration during land use planning and allowing for local decision-making.
  • Start expanding PAs by first designating coastal wetlands adjacent to existing MPAs/PAs/IPLs.
  • Increase designated PAs and MPAs and consider all benefits (e.g., climate, human well-being, biodiversity) and dynamics (e.g., water flows, soil, agriculture) when designating PAs to ensure maximum benefits.
  • Ensure PAs and MPAs don’t displace, violate rights, or reduce access to vital resources for local and Indigenous communities.
  • Classify and map coastal wetlands and tidal information; create local, national, and international standards for classification.
  • Integrate river, watershed, and dam management into coastal wetland protection.
  • Streamline regulations and legal requirements, when possible to simplify management and designation of MPAs/PAs/IPLs.
  • Use financial incentives such as subsidies, tax breaks, payments for ecosystem services (PES), and debt-for-nature swaps to protect coastal wetlands from development.
  • Conduct proactive land-use planning to avoid roads and other development projects that might interfere with MPAs and PAs.
  • Coordinate MPA and PA efforts horizontally (e.g., across agencies) and vertically (e.g., across subnational, national, and international efforts), ensuring an inclusive process for local and Indigenous communities.
  • Incorporate MPAs/PAs/IPLs into local, national, and international climate plans (i.e., Nationally Determined Contributions).
  • Work with insurance companies to reduce insurance premiums for properties that protect or maintain coastal wetlands.
  • Create processes for legal grievances, dispute resolution, and restitution.
  • Create sustainable use regulations for protected coastal wetland areas that provide resources to local communities.
  • Empower local communities to manage coastal wetlands and ensure a participatory approach to designating and managing MPAs and PAs.
  • Create education programs that educate the public on MPA regulations, the benefits of coastal wetlands, and how to use resources sustainably.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.

Further information:

Practitioners
  • Avoid draining or degrading coastal wetlands.
  • Avoid developing intact coastal wetlands, including small-scale shoreline developments such as docks.
  • Invest in coastal wetland conservation, restoration, sustainable management practices, specialized research facilities, and other R&D efforts.
  • Participate in stakeholder engagements and help policymakers designate coastal wetlands, create regulations, and implement robust monitoring and enforcement.
  • Grant Indigenous communities full property rights and autonomy and support them in monitoring, managing, and enforcing PAs.
  • Ensure protected coastal wetlands don’t displace, violate rights, or reduce access to vital resources for local and Indigenous communities.
  • Integrate river, watershed, and dam management into coastal wetland protection.
  • Use real-time monitoring and satellite data to manage and enforce PA and MPA regulations.
  • Create sustainable use regulations for protected coastal wetland areas that provide resources to the local community.
  • Conduct proactive land-use planning to avoid infrastructure or development projects that might interfere with protected coastal wetlands or incentivize drainage.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over PAs and MPAs.
  • Advocate for or use financial incentives such as subsidies, tax breaks, and PES to protect coastal wetlands from development.
  • Utilize financial mechanisms such as biodiversity offsets, PES, high-integrity voluntary carbon markets, and debt-for-nature swaps to fund coastal wetland protection.
  • Help classify and map coastal wetlands and tidal information as well as create local, national, and international standards for classification.
  • Coordinate PA and MPA efforts horizontally (e.g., across agencies) and vertically (e.g., across subnational, national, and international efforts), ensuring an inclusive process for local and Indigenous communities.
  • Work with insurance companies to reduce insurance premiums for properties that protect or maintain coastal wetlands.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.
  • Create education programs that educate the public on MPA/PA/IPL regulations, the benefits of coastal wetlands, and how to use resources sustainably.

Further information:

Business Leaders
  • Ensure operations, development, and supply chains are not degrading coastal wetlands or interfering with PA or MPA management.
  • Integrate coastal wetland protection into net-zero strategies, if relevant.
  • Help revise existing or create new high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Only purchase carbon credits from high-integrity, verifiable carbon markets, and do not use them as replacements for less carbon-intensive operations or claim them as offsets.
  • Consider donating to established coastal wetland protection funds in place of carbon credits.
  • Take advantage of financial incentives such as subsidies, tax breaks, and PES to coastal wetlands from development.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Invest in and support Indigenous and local communities' capacity for management, legal protection, and public relations.
  • Leverage political influence to advocate for stronger coastal wetland protection policies at national and international levels.
  • Conduct proactive land-use planning to avoid roads and other development projects that might interfere with PAs and MPAs or incentivize deforestation.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.

Further information:

Nonprofit Leaders
  • Advocate for enhanced enforcement of existing MPAs/PAs/IPLs, expansion of new MPAs/PAs/IPLs, and more public investments.
  • Help manage and monitor protected coastal wetlands using real-time monitoring and satellite data.
  • Provide financial support for MPAs/PAs/IPLs, monitoring, and enforcement.
  • Help conduct proactive land-use planning to avoid infrastructure or development projects that might interfere with protected coastal wetlands or incentivize drainage.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over PAs or MPAs.
  • Help revise existing or create new high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Invest in and support the capacity of Indigenous and local communities for management, legal protection, and public relations.
  • Use or advocate for financial incentives such as subsidies, tax breaks, and PES to protect coastal wetlands from development.
  • Help classify and map coastal wetlands and tidal information as well as create local, national, and international standards for classification.
  • Work with insurance companies to reduce insurance premiums for properties that protect or maintain coastal wetlands.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.
  • Create education programs that educate the public on MPA/PA/IPL regulations, the benefits of coastal wetlands, and how to use resources sustainably.

Further information:

Investors
  • Ensure investment portfolios do not degrade coastal wetlands or interfere with MPAs/PAs/IPLs, using data, information, and the latest technology to inform investments.
  • Invest in coastal wetland protection, monitoring, management, and enforcement mechanisms.
  • Use financial mechanisms such as credible biodiversity offsets, PES, voluntary high-integrity carbon markets, and debt-for-nature swaps to fund coastal wetland protection.
  • Invest in and support Indigenous and local communities' capacity for legal protection and public relations.
  • Share data, information, and investment frameworks that successfully avoid investments that drive coastal wetland destruction with other investors and nongovernmental organizations.
  • Provide favorable loans to Indigenous communities and entrepreneurs and businesses protecting wetlands.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.

Further information:

Philanthropists and International Aid Agencies
  • Advocate for enhanced enforcement of existing MPAs/PAs/IPLs, expansion of new MPAs/PAs/IPLs, and public investments.
  • Help manage and monitor protected coastal wetlands, using real-time monitoring and satellite data.
  • Provide technical and financial assistance to low- and middle-income countries and communities to protect coastal wetlands.
  • Provide financial support to organizations and institutions developing and deploying monitoring technology and conducting wetland research.
  • Help manage and monitor protected coastal wetlands using real-time monitoring and satellite data.
  • Help conduct proactive land-use planning to avoid infrastructure or development projects that might interfere with protected coastal wetlands or incentivize drainage.
  • Help revise existing or create new high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Invest in and support Indigenous and local communities' capacity for management, legal protection, and public relations.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over PAs or MPAs.
  • Help classify and map coastal wetlands and tidal information as well as create local, national, and international standards for classification.
  • Work with insurance companies to reduce insurance premiums for properties that protect or maintain coastal wetlands.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.
  • Create education programs that educate the public on MPA/PA/IPL regulations, the benefits of coastal wetlands, and how to use resources sustainably.

Further information:

Thought Leaders
  • Advocate for enhanced enforcement of existing MPAs/PAs/IPLs, expansion of new MPAs/PAs/IPLs, and for public investments.
  • Advocate for or use financial incentives such as subsidies, tax breaks, PES, and debt-for-nature swaps to protect coastal wetlands from development.
  • Help manage and monitor protected coastal wetlands using real-time monitoring and satellite data.
  • Help conduct proactive land-use planning to avoid infrastructure or development projects that might interfere with protected coastal wetlands or incentivize drainage.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over PAs or MPAs.
  • Help revise existing or create new high-integrity carbon and biodiversity markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Support Indigenous and local communities' capacity for legal protection, management, and public relations.
  • Help classify and map coastal wetlands and tidal information as well as create local, national, and international standards for classification.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.
  • Create programs that educate the public on MPA/PA/IPL regulations, the benefits of coastal wetlands, and how to use resources sustainably.

Further information:

Technologists and Researchers
  • Study ecosystem services provided by coastal wetlands and catalogue the benefits.
  • Improve mapping of coastal wetland areas, carbon content and dynamics, tidal impacts, degradation types and levels, and emissions data – specifically methane and nitrous oxide.
  • Improve monitoring methods using field measurements, models, satellite imagery, and GIS tools.
  • Research adjacent technologies and practices such as seaweed farm management, kelp forest conservation, sediment management, and biodiversity restoration.
  • Conduct meta-analyses or synthesize existing literature on coastal wetlands and protection efforts.
  • Explore ways to use smart management systems for PAs and MPAs, including the use of real-time and satellite data.
  • Develop land-use planning tools that help avoid infrastructure or development projects that might interfere with PAs and MPAs or incentivize drainage.
  • Create tools for local communities to monitor coastal wetlands, such as mobile apps, e-learning platforms, and mapping tools.
  • Develop verifiable carbon credits using technology such as blockchain to improve the integrity of carbon markets.
  • Develop supply chain tracking software for investors and businesses seeking to create sustainable portfolios and products.

Further information:

Communities, Households, and Individuals
  • Avoid draining or degrading coastal wetlands.
  • Avoid developing intact coastal wetlands, including small-scale shoreline developments such as docks.
  • Help manage and monitor protected coastal wetlands using real-time monitoring and satellite data.
  • Establish coordinating bodies for farmers, developers, landowners, policymakers, dam operators, and other stakeholders to holistically manage PAs.
  • Advocate for enhanced enforcement of existing MPAs/PAs/IPLs, expansion of new MPAs/PAs/IPLs, and public investments.
  • Help conduct proactive land-use planning to avoid infrastructure or development projects that might interfere with protected coastal wetlands or incentivize drainage.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over PAs or MPAs.
  • Help revise existing or create new high-integrity carbon and biodiversity markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Support Indigenous communities' capacity for management, legal protection, and public relations.
  • Use or advocate for financial incentives such as subsidies, tax breaks, and PES to protect coastal wetlands from development.
  • Help classify and map coastal wetlands and tidal information as well as create local, national, and international standards for classification.
  • Ensure PAs and MPAs don’t displace, violate rights, or reduce access to vital resources for local and Indigenous communities.
  • Work with insurance companies to reduce insurance premiums for properties that protect or maintain coastal wetlands.
  • Participate or volunteer in local coastal wetland protection efforts.
  • Plant native species to help improve the local ecological balance and stabilize the soil – especially on waterfront property.
  • Use nontoxic cleaning and gardening supplies, purchase unbleached paper products, and recycle to help keep pollution and debris out of wetlands.
  • Join, support, or create certification schemes for sustainable management of coastal wetlands.
  • Create education programs that educate the public on MPA/PA/IPL regulations, the benefits of coastal wetlands, and how to use resources sustainably.

Further information:

Sources
Evidence Base

Consensus of effectiveness in reducing emissions and maintaining carbon removal: High

There is high scientific consensus that coastal wetland protection is an important strategy for reducing wetland loss due to degradation and that degradation results in carbon stock loss from coastal wetlands. Rates of wetland loss are generally lower inside PAs than outside them. An analysis of over 4,000 PAs (wetland and non-wetland area) showed 59% of sites are in “sound management,” which generally reflects PAs with strong enforcement, management implementation, and conservation outcome indicators (Leverington et al., 2010). Here we used a conservative effectiveness of 59% for salt marshes and mangroves that are under legal protection, consistent with the value from Leverington et al. (2010). Other regional studies show similar PA effectiveness values, with 25–50% of wetland PAs in China exhibiting moderate to very high conservation effectiveness (Lu et al., 2016).

Seagrasses differ from mangroves and salt marshes in that they fall under MPA designation because they are subtidal, or submerged. In an analysis of effectiveness of 66 MPAs in 18 countries, nearly 53% of MPAs reported positive or slightly positive ecosystem outcomes (Rodríguez-Rodríguez & Martínez-Vega, 2022). Less is known about MPA effectiveness for seagrass meadows specifically; we assumed an effectiveness of 53% – similar to other MPAs.

Prevention of degradation via legal coastal wetlands protection avoids emissions by preserving carbon stocks while also retaining carbon sequestration capacity. Degradation of coastal wetlands results in measurable loss of short- and long-lived carbon stocks, with emissions that vary based on ecosystem and degradation type (Donato et al., 2011, Holmquist et al., 2023, Lovelock et al., 2017, Mcleod et al., 2011, Pendleton et al., 2012). Estimates of existing carbon stocks in coastal wetlands are substantial, ranging between 8.97–32.7 Gt of carbon (32.9–120 Gt CO₂‑eq ), most of which is likely susceptible to degradation (Macreadie et al., 2021).

The results presented in this document synthesize findings from 14 global datasets. We recognize that geographic bias in the information underlying global data products creates bias and hope this work inspires research and data sharing on this topic in underrepresented regions and understudied ecosystems.

Appendix

In this analysis, we integrated global land cover data; shapefiles of PAs, MPAs, and IPLs; and ecosystem type (mangroves, salt marshes, seagrasses) data on carbon emissions and sequestration rates to calculate currently protected coastal wetland area, total global coastal wetland area, and avoided emissions and additional sequestration from coastal wetland protection by ecosystem type (mangroves, salt marshes, and seagrasses).

Land Cover Data

We used two land cover data products to estimate coastal wetland extent by ecosystem type (mangroves, salt marshes, seagrasses) inside and outside of PAs, MPAs, and IPLs: 1) a global 30 m wetland map, GWL_FCS30, for mangroves and salt marshes (Zhang et al., 2023), and 2) the global distribution of seagrasses map from UN Environment World Conservation Monitoring Centre (UNEP-WCMC & Short, 2021).

Protected Coastal Wetland Areas

The IUCN defines PAs, including MPAs, as geographically distinct areas managed primarily for the long-term conservation of nature and ecosystem services. They are further disaggregated into six levels of protection, ranging from strict wilderness preserves to sustainable use areas that allow for some natural resource extraction (including logging). We calculated all levels of protection but only considered protection categories I–IV in our analysis of adoption. We recognized that other protection categories might provide conservation benefits. We excluded categories labeled as “Not Applicable (NAP),” “Not Reported (NR),” “Not Assigned (NAS),” as well as categories VI and VII. We also estimated IPL area based on available data, but emphasized that much of their extent has not been fully mapped nor recognized for its conservation benefits (Garnett et al., 2018). Additionally, the IPL dataset only covered land and therefore did not include seagrass ecosystems explicitly beyond the extent that ecosystems bordering terrestrial IPL areas were captured within the 1 km pixels of analysis. Coastal wetlands also lack data on the effectiveness of protection with IPLs, so we did not include IPL data as currently protected in our estimates.

We identified protected coastal wetland areas using the World Database on PAs (UNEP-WCMC & IUCN, 2024), which contains boundaries for each PA or MPA and additional information, including their establishment year and IUCN management category (Ia to VI, NAP, NR, and NAS). For each PA or MPA polygon, we extracted the coastal wetland area based on the datasets in the Land Cover Data section. Our spatial analysis required the center point of the pixel of each individual ecosystem under consideration to be covered by the PA or MPA polygon in order to be classified as protected, which is a relatively strict spatial extraction technique that likely leads to lower estimates of conservation compared to previous work with differing techniques (Dabalà et al., 2023).

We used the maps of IPLs from Garnett et al. (2018) to identify IPLs that were not inside of established PAs. We calculated the total coastal wetland area within IPLs (excluding PAs and MPAs) using the same coastal wetland data sources.

Coastal Wetland Loss, Additional Sequestration, and Emissions Factors

We aggregated coastal wetland loss rates by ecosystem type (mangroves, salt marshes, seagrasses). We used data on PA and MPA effectiveness to calculate the difference in coastal wetland loss rates attributable to protection (Equation A1). We compiled baseline estimates of current rates of coastal wetland degradation from all causes (%/yr) from existing literature as shown in the “Detailed coastal wetland loss data” tab of the Supporting Data spreadsheet and used in conjunction with estimates of reductions in loss, 53–59%, associated with protection.

Equation A1.

\[ Wetland\text{ }loss_{avoided}=(Wetland\text{ }loss_{baseline}\times Reduction\text{ }in\text{ }loss) \]

We then used the ratio of coastal wetland loss in unprotected areas versus PAs to calculate avoided CO₂ emissions and additional carbon sequestration for each adoption unit. Specifically, we estimated the carbon benefits of avoided coastal wetland loss by multiplying avoided coastal wetland loss by avoided CO₂ emissions (30-yr time horizon; Equation A2) and carbon sequestration rates (30-yr time horizon; Equation A3) for each ecosystem type. Importantly, the emissions factors we used account for carbon in above- and below-ground biomass and generally do not assume 100% loss of carbon stocks because many land use impacts may retain some stored carbon, some of which is likely resistant to degradation (see the “2. current state effectiveness tab” in the spreadsheet for more information). We derived our estimates of retained carbon sequestration from global databases on sediment organic carbon burial rates in each ecosystem (see the “2. current state effectiveness tab” in the spreadsheet for more information).

Equation A2.

\[ Avoided\text{ } emissions = Wetland\text{ }loss_{avoided} \times \sum_{t=1}^{30}{Emissions} \]

Equation A3.

\[ Sequestration = Wetland\text{ }loss_{avoided} \times \sum_{t=1}^{30}{Sequestration} \]

We then estimated effectiveness (Equation A4) as the avoided CO₂ emissions and the retained carbon sequestration capacity attributable to the reduction in wetland loss conferred by protection estimated in Equations S1–S3.

Equation A4.

\[ Effectiveness = Wetland\text{ }loss_{avoided} \times (Carbon_{avoided\text{ } emissions} + Carbon_{sequestration}) \]

Finally, we calculated climate impact (Equation A5) by multiplying the adoption area under consideration by the estimated effectiveness from Equation A4.

Equation A5.

\[ Climate\text{ }impact = Effectiveness \times Adoption \]

Appendix References

Garnett, S. T., Burgess, N. D., Fa, J. E., Fernández-Llamazares, Á., Molnár, Z., Robinson, C. J., Watson, J. E. M., Zander, K. K., Austin, B., Brondizio, E. S., Collier, N. F., Duncan, T., Ellis, E., Geyle, H., Jackson, M. V., Jonas, H., Malmer, P., McGowan, B., Sivongxay, A., & Leiper, I. (2018). A spatial overview of the global importance of Indigenous lands for conservation. Nature Sustainability, 1(7), 369–374. https://doi.org/10.1038/s41893-018-0100-6

UNEP-WCMC, & Short, F. T. (2021). Global distribution of seagrasses (version 7.1) [Data set]. UN Environment World Conservation Monitoring Centre. https://doi.org/10.34892/x6r3-d211

UNEP-WCMC, & IUCN. (2024). Protected planet: The world database on protected areas (WDPA) and world database on other effective area-based conservation measures (WD-OECM) [Data set]. Retrieved November 2024, from https://www.protectedplanet.net

Zhang, X., Liu, L., Zhao, T., Chen, X., Lin, S., Wang, J., Mi, J., & Liu, W. (2023). GWL_FCS30: a global 30 m wetland map with a fine classification system using multi-sourced and time-series remote sensing imagery in 2020. Earth System Science Data, 15(1), 265–293. https://doi.org/10.5194/essd-15-265-2023

Updated Date

Protect Peatlands

Submitted by Drawdown Admin on
Sector
FALO & Nature-Based Carbon Removal
Mode
Cut Emissions and Remove Carbon
Cluster
Protect & Manage Ecosystems
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Peatland
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Summary

The Protect Peatlands solution is defined as legally protecting peatland ecosystems through establishment of protected areas (PAs), which preserves stored carbon and ensures continued carbon sequestration by reducing degradation of the natural hydrology, soils, and/or vegetation. This solution focuses on non-coastal peatlands that have not yet been drained or otherwise severely degraded. Reducing emissions from degraded peatlands is addressed in the Restore Peatlands solution, and mangroves located on peat soils are addressed in the Protect Coastal Wetlands solution.

Extreme weather events
Income & work,Health
Nature protection,Water resources,Water quality
Description for Social and Search
Protect Peatlands is a HIghly Recommended climate solution. Peatland soils accumulate huge amounts of carbon over centuries. Protecting peatlands reduces disturbances that turn these powerful carbon sinks into major sources of GHG emissions.
Overview

Peatlands are diverse ecosystems characterized by waterlogged, carbon-rich peat soils consisting of partially decomposed dead plant material (Figure 1). They are degraded or destroyed through clearing of vegetation and drainage for agriculture, forestry, peat extraction, or other development. An estimated 600 Gt carbon (~2,200 Gt CO₂‑eq ) is stored in peatlands, twice as much as the carbon stock in all forest biomass (Yu et al., 2010; Pan et al., 2024). Because decomposition occurs very slowly under waterlogged conditions, large amounts of plant material have accumulated in a partially decomposed state over millennia. These carbon-rich ecosystems occupy only 3–4% of land area (Xu et al., 2018b; United Nations Environment Programme [UNEP], 2022). Their protection is both feasible due to their small area and highly impactful due to their carbon density.

Figure 1. These photos show the diversity of peatlands that occur in different places, including a fen peatland and meadow complex in California (top left), a peat swamp in Indonesia (top right), a peat fen and forest in Canada (bottom left), and a peat bog in New Hampshire (bottom right). 

Examples of peatland types

Photo credits: Catie and Jim Bishop | U.S. Department of Agriculture; Rhett A. Butler; Garth Lenz; Linnea Hanson | U.S. Department of Agriculture

When peatlands are drained or disturbed, the rate of carbon loss increases sharply as the accumulated organic matter begins decomposing (Figure 2). Removal of overlying vegetation produces additional GHG emissions while also slowing or stopping carbon uptake. Whereas emissions from vegetation removal occur rapidly following disturbance, peat decomposition and associated emissions can continue for centuries depending on environmental conditions and peat thickness. Peat decomposition after disturbance occurs faster in warmer climates because cold temperatures slow microbial activity. In this analysis, we evaluated tropical, subtropical, temperate, and boreal regions separately.

Figure 2. Greenhouse gas emissions and sequestration in intact peatlands (left) and a drained peatland (right). Intact peatlands are a net greenhouse gas sink, sequestering carbon in peat through photosynthesis but also emitting methane due to waterlogged soils. Drained peatlands are a greenhouse gas source, producing emissions from peat decomposition and drainage canals. Modified from IUCN UK Peatland Programme (2024).

Diagram comparing healthy and degraded peatland

Source:  IUCN UK Peatland Programme. (2024, July 10). New briefing addresses the peatlands and methane debate.

In addition to peat decomposition, biomass removal, and lost carbon sequestration, peatland disturbance impacts methane and nitrous oxide emissions and carbon loss through waterways (Figure 2; Intergovernmental Panel on Climate Change [IPCC] Task Force on National Greenhouse Gas Inventories, 2014; UNEP, 2022). Intact peatlands are a methane source because of methane-producing microbes, which thrive under waterlogged conditions. However, carbon uptake typically outweighs methane emissions. Leifield et al. (2019) found that intact peatlands are a net carbon sink of 0.77 ± 0.15 t CO₂‑eq /ha/yr in temperate and boreal regions and 1.65 ± 0.51 t CO₂‑eq /ha/yr in tropical regions after accounting for methane emissions. Peatland drainage reduces methane emissions from the peatland itself, but the drainage ditches can become potent methane sources (Evans et al., 2015; Peacock et al., 2021). Dissolved and particulate organic carbon also run off through drainage ditches, increasing CO₂ emissions in waterways from microbial activity and abiotic processes. Finally, rates of nitrous oxide emissions increase following drainage as the nitrogen stored in the peat becomes available to microbes. 

Patterns of ongoing peatland drainage are poorly understood at the global scale, but rates of ecosystem disturbance are generally lower in PAs and on Indigenous peoples’ lands than outside of them (Li et al., 2024b; Wolf et al., 2021; Sze et al., 2021). The International Union for Conservation of Nature (IUCN) defines six levels of PAs that vary in their allowed uses, ranging from strict wilderness preserves to sustainable use areas that allow for some extraction of natural resources. All PA levels were included in this analysis (UNEP World Conservation Monitoring Center [UNEP-WCMC] and IUCN, 2024). Due to compounding uncertainties in the distributions of peatlands and Indigenous peoples’ lands, which have not yet been comprehensively mapped, and unknown rates of peatland degradation within Indigenous people’s lands, peatlands within Indigenous peoples’ lands were excluded from the tables but are discussed in the text (Garnett et al., 2018; UNEP-WCMC and IUCN, 2024). 

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Xu, J., Morris, P. J., Liu, J., & Holden, J. (2018a). Hotspots of peatland-derived potable water use identified by global analysis. Nature Sustainability, 1(5), 246–253. Link to source: https://doi.org/10.1038/s41893-018-0064-6

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Credits

Lead Fellow

  • Avery Driscoll

Contributors

  • Ruthie Burrows, Ph.D.

  • James Gerber, Ph.D.

  • Daniel Jasper

  • Alex Sweeney

Internal Reviewers

  • Aiyana Bodi

  • Hannah Henkin

  • Megan Matthews, Ph.D.

  • Ted Otte

  • Christina Swanson, Ph.D.

  • Paul C. West, Ph.D.

Effectiveness

We estimated that protecting a ha of peatland avoids 0.92–13.47 t CO₂‑eq /ha/yr, with substantially higher emissions reductions in subtropical and tropical regions and lower emissions reductions in boreal regions (100-yr GWP; Table 1a–d; Appendix). 

We estimated effectiveness as the avoided emissions attributable to the reduction in peatland loss conferred by protection (Equation 1). First, we calculated the biome-specific difference between the annual rate of peatland loss outside PAs (Peatland lossbaseline) versus inside PAs (Peatland lossprotected) (Appendix; Conchedda & Tubellio, 2020; Davidson et al., 2014; Miettinen et al., 2011; Miettinen et al., 2016; Uda et al., 2017, Wolf et al., 2021). We then multiplied the avoided peatland loss by the total emissions from one ha of drained peatland over 30 years. This is the sum of the total biomass carbon stock (Carbonbiomass), which degrades relatively quickly; 30 years of annual emissions from peat itself (Carbonflux); and 30 years of lost carbon sequestration potential, reflecting the carbon that would have been taken up by one ha of intact peatland in the absence of degradation (Carbonuptake) (IPCC Task Force on National Greenhouse Gas Inventories, 2014; UNEP, 2022). The carbon flux includes CO₂‑eq emissions from: 1) peat oxidation, 2) dissolved organic carbon loss through drainage, 3) the net change in on-field methane between undrained and drained states, 4) methane emissions from drainage ditches, and 5) on-field nitrous oxide emissions.

Equation 1.

\[Effectiveness = (Peatland\text{ }loss_{baseline} - Peatland\text{ }loss_{protected})\times( Carbon_{biomass} + 30\cdot Carbon_{flux} + 30\cdot Carbon_{uptake}) \]

Without rewetting, peat loss typically persists beyond 30 years and can continue for centuries (Leifield & Menichetti, 2018). Thus, this is a conservative estimate of peatland protection effectiveness that captures near-term impacts, aligns with the 30-yr cost amortization time frame, and is roughly consistent with commonly used 2050 targets. Using a longer time frame produces larger estimates of emissions from degraded peatlands and therefore higher effectiveness of peatland protection.

The effectiveness of peatland protection as defined here reflects only a small percentage of the carbon stored in peatlands because we account for the likelihood that the peatland would be destroyed without protection. Peatland protection is particularly impactful for peatlands at high risk of drainage.

Table 1. Effectiveness of peatland protection at avoiding emissions and sequestering carbon. Regional differences in values are driven by variation in emissions factors and baseline rates of peatland drainage.

Unit: t CO₂‑eq , 100-yr basis/ha of peatland protected/yr

Estimate 0.92

Unit: t CO₂‑eq , 100-yr basis/ha of peatland protected/yr

Estimate 4.42

Unit: t CO₂‑eq , 100-yr basis/ha of peatland protected/yr

Estimate 13.47

Unit: t CO₂‑eq , 100-yr basis/ha of peatland protected/yr

Estimate 13.23
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Cost

We estimated that the net cost of peatland protection is approximately US$1.5/ha/yr, or $0.25/t CO₂‑eq avoided (Table 2). Data related to the costs of peatland protection are very limited. These estimates reflect global averages rather than regionally specific values, and rarely include data specific to peatlands. The costs of peatland protection include up-front costs of land acquisition and ongoing costs of management and enforcement. The market price of land reflects the opportunity cost of not using the land for other purposes, such as agriculture, forestry, peat extraction, or urban development. Protecting peatlands can also generate revenue through increased tourism. Costs and revenues are highly variable across regions, depending on the costs of land and enforcement and potential for tourism. 

Dienerstein et al. (2024) estimated the initial cost of establishing a protected area for 60 high-biodiversity ecoregions. Amongst the 33 regions that were likely to contain peatlands, the median acquisition cost was US$957/ha, which we amortized over 30 years. Costs of protected area maintenance were estimated at US$9–17/ha/yr (Bruner et al., 2004; Waldron et al., 2020), though these estimates were not specific to peatlands. Additionally, these estimates reflect the costs of effective enforcement and management, but many existing protected areas lack adequate funds for effective enforcement (Adams et al., 2019; Barnes et al., 2018; Burner et al., 2004). Waldron et al. (2020) estimated that, across all ecosystems, tourism revenues directly attributable to protected area establishment were US$43/ha/yr, not including downstream revenues from industries that benefit from increased tourism. Inclusion of a tourism multiplier would substantially increase the estimated economic benefits of peatland protection.

Table 2. Cost per unit climate impact for peatland protection.

Unit: 2023 US$/t CO₂‑eq , 100-yr basis

Median 0.25
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Methods and Supporting Data

Methods and Supporting Data

Learning Curve

A learning curve is defined here as falling costs with increased adoption. The costs of peatland protection do not fall with increasing adoption, so there is no learning curve for this solution.

Speed of Action

Speed of action refers to how quickly a climate solution physically affects the atmosphere after it is deployed. This is different from speed of deployment, which is the pace at which solutions are adopted.

At Project Drawdown, we define the speed of action for each climate solution as gradual, emergency brake, or delayed.

Protect Peatlands is an EMERGENCY BRAKE climate solution. It has the potential to deliver a more rapid impact than gradual and delayed solutions. Because emergency brake solutions can deliver their climate benefits quickly, they can help accelerate our efforts to address dangerous levels of climate change. For this reason, they are a high priority.

Caveats

Permanence, or the durability of stored carbon, is a caveat for emissions avoidance through peatland protection that is not addressed in this analysis. Protected peatlands could be drained if legal protections are reversed or inadequately enforced, resulting in the loss of stored carbon. Additionally, fires on peatlands have become more frequent due to climate change (Turetsky et al., 2015; Loisel et al., 2021), and can produce very large emissions pulses (Konecny et al., 2016; Nelson et al., 2021). In boreal regions, permafrost thaw can trigger large, sustained carbon losses from previously frozen peat (Hugelius et al., 2020; Jones et al., 2017). In tropical regions, climate change-induced changes in precipitation can lower water tables in intact peatlands, increasing risks of peat loss and reducing sequestration potential (Deshmukh et al., 2021). 

Additionality, or the degree to which emissions reductions are above and beyond a baseline, is another important caveat for emissions avoidance through ecosystem protection (Atkinson & Alibašić, 2023; Fuller et al., 2020; Williams et al., 2023). In this analysis, additionality was addressed by using baseline rates of peatland degradation in calculating effectiveness. Evaluating additionality is challenging and remains an active area of research.

Finally, there are substantial uncertainties in the available data on peatland areas and distributions, peatland loss rates, the drivers of peatland loss, the extent and boundaries of PAs, and the efficacy of PAs at reducing peatland disturbance. Emissions dynamics on both intact and cleared peatlands are also uncertain, particularly under different land management practices and in the context of climate change.

Current Adoption

Because peatlands are characterized by their soils rather than by overlying vegetation, they are difficult to map at the global scale (Minasny et al., 2024). Mapping peatlands remains an active area of research, and the adoption values presented here are uncertain. We estimated that 22.6 Mha of peatlands are located within strictly protected PAs (IUCN classes I or II), and 82.3 Mha are within other or unknown PA classes (Table 3a–e; UNEP, 2022; UNEP-WCMC & IUCN, 2024), representing 22% of total global peatland area (482 Mha). Because of data limitations, we did not include Indigenous peoples’ lands in subsequent analyses despite their conservation benefits. There are an additional 186 Mha of peatlands within Indigenous peoples’ lands that are not classified as PAs, with a large majority (155 Mha) located in boreal regions (Table 3; Garnett et al., 2018; UNEP, 2022).

Given the uncertainty in the global extent of peatlands, estimates of peatland protection vary. The Global Peatlands Assessment estimated that 19% (90.7 Mha) of peatlands are protected (UNEP, 2022), with large regional variations ranging from 35% of peatlands protected in Africa to only 10% in Asia. Using a peatland map from Melton et al. (2022), Austin et al. (2025) estimated that 17% of global peatlands are within PAs, and an additional 27% are located in Indigenous peoples’ lands (excluding Indigenous peoples’ lands in Canada covering large peatland areas).

Table 3. Current peatland area under protection by biome (circa 2023). Estimates are provided for two different forms of protection: “strict” protection, including IUCN classes I and II, and “nonstrict” protection, including all other IUCN classes. Regional values may not sum to global totals due to rounding.

Unit: Mha protected

Area within strict PAs 12.4
Area within non-strict PAs 41.7

Unit: Mha protected

Area within strict PAs 3.0
Area within non-strict PAs 10.1

Unit: Mha protected

Area within strict PAs 1.1
Area within non-strict PAs 1.6

Unit: Mha protected

Area within strict PAs 6.1
Area within non-strict PAs 28.9

Unit: Mha protected

Area within strict PAs 22.6
Area within non-strict PAs 82.3
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Adoption Trend

We calculated the annual rate of new peatland protection based on the year of PA establishment for areas established in 2000–2020. The median annual increase in peatland protection was 0.86 Mha (mean 2.0 Mha; Table 4a–d). This represents a roughly 0.8%/yr increase in peatlands within PAs, or protection of an additional 0.2%/yr of total global peatlands. This suggests that peatland protection is likely occurring at a somewhat slower rate than peatland degradation – which is estimated to be around 0.5% annually at the global scale – though this estimate is highly uncertain and spatially variable (Davidson et al., 2014).

There were large year-to-year differences in how much new peatland area was protected over this period, ranging from only 0.2 Mha in 2016 to 7.9 Mha in 2007. The rate at which peatland protection is increasing has been decreasing, with a median increase of 1.7 Mha/yr between 2000 and 2010 declining to 0.7 Mha/yr during 2010–2020. Recent median adoption of peatland protection by area is highest in boreal (0.5 Mha/yr, Table 4a) and tropical regions (0.2 Mha/yr, Table 4d), followed by temperate regions (0.1 Mha/yr, Table 4b) and subtropical regions (0.01 Mha/yr, Table 4c) (2010–2020). Scaled by total peatland area, however, recent rates of peatland protection are lowest in the subtropics (0.04%/yr), followed by the boreal (0.14%/yr), the tropics (0.16%/yr), and temperate regions (0.19%/yr).

Table 4. Adoption trend for peatland protection in PAs of any IUCN class (2000–2020). The 25th and 75th percentiles reflect only interannual variance.

Unit: Mha of peatland protected/yr

25th percentile 0.24
Mean 0.87
Median (50th percentile) 0.50
75th percentile 0.89

Unit: Mha of peatland protected/yr

25th percentile 0.07
Mean 0.23
Median (50th percentile) 0.10
75th percentile 0.28

Unit: Mha of peatland protected/yr

25th percentile 0.00
Mean 0.04
Median (50th percentile) 0.01
75th percentile 0.04

Unit: Mha of peatland protected/yr

25th percentile 0.05
Mean 0.84
Median (50th percentile) 0.25
75th percentile 0.83
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Adoption Ceiling

We considered the adoption ceiling to include all undrained, non-coastal peatlands and estimated this to be 425 Mha, based on the Global Peatlands Database and Global Peatlands Map (UNEP, 2022; Table 5e; Appendix). We estimated that 284 Mha of undrained peatlands remain in boreal regions (Table 5a), 26 Mha in temperate regions (Table 5b), 12 Mha in the subtropics (Table 5c), and 103 Mha in the tropics (Table 5d). The adoption ceiling represents the technical upper limit to adoption of this solution.

There is substantial uncertainty in the global extent of peatlands, which is not quantified in these adoption ceiling values. Estimates of global peatland extent from recent literature include 404 Mha (Melton et al., 2022), 423 Mha (Xu et al., 2018b), 437 Mha (Müller & Joos, 2021), 463 Mha (Leifield & Menichetti, 2018), and 488 Mha (UNEP, 2022). Several studies suggest that the global peatland area may still be underestimated (Minasny et al., 2024; UNEP, 2022). 

Table 5. Adoption ceiling: upper limit for adoption of legal protection of peatlands by biome. Values may not sum to global totals due to rounding.

Unit: Mha protected

Peatland area (Mha) 284

Unit: Mha protected

Peatland area (Mha) 26

Unit: Mha protected

Peatland area (Mha) 12

Unit: Mha protected

Peatland area (Mha) 103

Unit: Mha protected

Peatland area (Mha) 425
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Achievable Adoption

UNEP (2022) places a high priority on protecting a large majority of remaining peatlands for both climate and conservation objectives. We defined the achievable range for peatland protection as 70% (low achievable) to 90% (high achievable) of remaining undrained peatlands. Only ~19% of peatlands are currently under formal protection within PAs (UNEP, 2022; UNEP-WCMC and IUCN, 2024). However, approximately 60% of undrained peatlands are under some form of protection if peatlands within Indigenous peoples’ lands are considered (Garnett et al., 2018; UNEP, 2022; UNEP-WCMC and IUCN, 2024). While ambitious, this provides support for our selected achievable range of 70–90% (Table 6a-e). 

Ensuring effective and durable protection of these peatlands from drainage and degradation, including secure land tenure for Indigenous peoples who steward peatlands and other critical ecosystems, is a critical first step. Research suggests that local community leadership, equitable stakeholder engagement, and cross-scalar governance are needed to achieve conservation goals while also balancing social and economic outcomes through sustainable use (Atkinson & Alibašić, 2023; Cadillo & Bennett, 2024; Girkin et al., 2023; Harrison et al., 2019; Suwarno et al., 2015). Sustainable uses of peatlands include some forms of paludiculture, which can involve peatland plant cultivation, fishing, or gathering without disturbance of the hydrology or peat layer (Tan et al., 2021).

Table 6. Range of achievable adoption of peatland protection by biome.

Unit: Mha protected

Current adoption 54
Achievable – low 199
Achievable – high 255
Adoption ceiling 284

Unit: Mha protected

Current adoption 13
Achievable – low 18
Achievable – high 24
Adoption ceiling 26

Unit: Mha protected

Current adoption 3
Achievable – low 9
Achievable – high 11
Adoption ceiling 12

Unit: Mha protected

Current adoption 35
Achievable – low 72
Achievable – high 92
Adoption ceiling 103

Unit: Mha protected

Current adoption 105
Achievable – low 297
Achievable – high 382
Adoption ceiling 425
Left Text Column Width

We estimated that PAs currently reduce emissions from peatland degradation by 0.6 Gt CO₂‑eq/yr (Table 7a-e). Achievable levels of peatland protection have the potential to reduce emissions 1.3–1.7 Gt CO₂‑eq/yr, with a technical upper bound of 1.9 Gt CO₂‑eq/yr. The estimate of climate impacts under current adoption does not include the large areas of peatlands protected by Indigenous peoples but not legally recognized as PAs. Inclusion of these areas would increase the current estimated impact of peatland protection to 0.9 Gt CO₂‑eq/yr.

Other published estimates of additional emissions reductions through peatland protection are somewhat lower, with confidence intervals of 0–1.2 Gt CO₂‑eq/yr (Griscom et al., 2017; Humpenöder et al., 2020; Loisel et al., 2021; Strack et al., 2022). These studies vary in their underlying methodology and data, including the extent of peatland, the baseline rate of peatland loss, the potential for protected area expansion, which GHGs are considered, the time frame over which emissions are calculated, and whether they account for vegetation carbon loss or just emissions from the peat itself. 

Table 7. Climate impact at different levels of adoption.

Unit: Gt CO₂ ‑eq/yr, 100-yr basis

Current adoption 0.05
Achievable – low 0.18
Achievable – high 0.24
Adoption ceiling 0.26

Unit: Gt CO₂ ‑eq/yr, 100-yr basis

Current adoption 0.06
Achievable – low 0.08
Achievable – high 0.11
Adoption ceiling 0.12

Unit: Gt CO₂ ‑eq/yr, 100-yr basis

Current adoption 0.04
Achievable – low 0.12
Achievable – high 0.15
Adoption ceiling 0.17

Unit: Gt CO₂ ‑eq/yr, 100-yr basis

Current adoption 0.46
Achievable – low 0.95
Achievable – high 1.22
Adoption ceiling 1.36

Unit: Gt CO₂ ‑eq/yr, 100-yr basis

Current adoption 0.61
Achievable – low 1.33
Achievable – high 1.71
Adoption ceiling 1.90
Left Text Column Width
Additional Benefits

Extreme Weather Events

Peatland protection can help communities adapt to extreme weather. Because peatlands regulate water flows, they can reduce the risk of droughts and floods (IUCN, 2021; Ritson et al., 2016). Evidence suggests that peatlands can provide a cooling effect to the immediate environment, lowering daytime temperatures and reducing temperature extremes between day and night (Dietrich & Behrendt, 2022; Helbig et al., 2020; Worrall et al., 2022).

Health

When peatlands are drained they are susceptible to fire. Peatland fires can significantly contribute to air pollution because of the way these fires smolder (Uda et al., 2019). Smoke and pollutants, particularly PM2.5, from peatland fires can harm respiratory health and lead to premature mortality (Marlier et al., 2019). A study of peatland fires in Indonesia estimated they contribute to the premature mortality of about 33,100 adults and about 2,900 infants annually (Hein et al., 2022). Researchers have linked exposure to PM2.5 from peatland fires to increased hospitalizations, asthma, and lost workdays (Hein et al., 2022). Peatland protection mitigates exposure to air pollution and can save money from reduced health-care expenditures (Kiely et al., 2021).

Income and Work

Peatlands support the livelihoods of nearby communities, especially those in low- and middle-income countries. In the peatlands of the Amazon and Congo basins, fishing livelihoods depend on aquatic wildlife (Thornton et al., 2020). Peatlands in the Peruvian Amazon provide important goods for trade, such as palm fruit and timber, and are used for hunting by nearby populations (Schulz et al., 2019). Peatlands can also support the livelihoods of women and contribute to gender equality. For example, raw materials – purun – from Indonesian peatlands are used by women to create and sell mats used in significant events such as births, weddings, and burials (Goib et al., 2018).

Nature Protection

Peatlands are home to a wide range of species, supporting biodiversity of flora and an abundance of wildlife (UNEP, 2022; Minayeva et al., 2017; Posa et al., 2011). Because of their unique ecosystem, peatlands provide a habitat for many rare and threatened species (Posa et al., 2011). A study of Indonesian peat swamps found that the IUCN Red List classified approximately 45% of mammals and 33% of birds living in these ecosystems as threatened, vulnerable, or endangered (Posa et al., 2011). Peatlands also support a variety of insect species (Spitzer & Danks, 2006). Because of their sensitivity to environmental changes, some peatland insects can act as indicators of peatland health and play a role in conservation efforts (Spitzer & Danks, 2006).

Water Resources

Peatlands can filter water pollutants and improve water quality and are important sources of potable water for some populations (Minayeva et al., 2017). Xu et al. (2018a) estimated that peatlands store about 10% of freshwater globally, not including glacial water. Peatlands are a significant drinking water source for people in the United Kingdom and Ireland, where they provide potable water for about 71.4 million people (Xu et al., 2018a).

Water Quality

See Water Resources section above.

Risks

Leakage occurs when peatland drainage and clearing moves outside of protected area boundaries and is a risk of relying on peatland protection as an emissions reduction strategy (Harrison & Paoli, 2012; Strack et al., 2022). If the relocated clearing also occurs on peat soils, emissions from peatland drainage and degradation are relocated but not actually reduced. If disturbance is relocated to mineral soils, however, the disturbance-related emissions will typically be lower. Combining peatland protection with policies to reduce incentives for peatland clearing can help avoid leakage.

Peatland protection must be driven by or conducted in close collaboration with local communities, which often depend on peatlands for their livelihoods and economic advancement (Jalilov et al., 2025; Li et al., 2024a; Suwarno et al., 2016). Failure to include local communities in conservation efforts violates community sovereignty and can exacerbate existing socioeconomic inequities (Felipe Cadillo & Bennet, 2024; Thorburn & Kull, 2015). Effective peatland protection requires development of alternative income opportunities for communities currently dependent on peatland drainage, such as tourism; sustainable peatland use practices like paludiculture; or compensation for ecosystem service provisioning, including carbon storage (Evers et al., 2017; Girkin et al., 2023; Suwarno et al., 2016; Syahza et al., 2020; Tan et al., 2021; Uda et al., 2017).

Interactions with Other Solutions

Reinforcing

Protected areas often include multiple ecosystems. Peatland protection will likely lead to protection of other ecosystems within the same areas, and the health of nearby ecosystems is improved by the services provided by intact peatlands. 

Restored peatlands need protection to reduce the risk of future disturbance, and the health of protected peatlands can be improved through restoration of adjacent degraded peatlands.

Competing

Protecting peatlands could limit land availability for renewable energy technologies and raw material and food production. Protect Peatlands competes with the following solutions for land.

Dashboard

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
0.92
units
Current 5.4×10⁷ 01.99×10⁸2.55×10⁸
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.05 0.180.24
US$ per t CO₂-eq
0
Emergency Brake

CO₂ , CH₄, N₂O

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
4.42
units
Current 1.3×10⁷ 01.8×10⁷2.4×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.06 0.080.11
US$ per t CO₂-eq
0
Emergency Brake

CO₂ , CH₄, N₂O

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
13.47
units
Current 3.0×10⁶ 09.0×10⁶1.1×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.04 0.120.15
US$ per t CO₂-eq
0
Emergency Brake

CO₂ , CH₄, N₂O

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
13.23
units
Current 3.5×10⁷ 07.2×10⁷9.2×10⁷
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.46 0.951.22
US$ per t CO₂-eq
0
Emergency Brake

CO₂ , CH₄, N₂O

Trade-offs

None

Action Word
Protect
Solution Title
Peatlands
Classification
Highly Recommended
Lawmakers and Policymakers
  • Set clear designations of remaining peatlands and implement robust monitoring and enforcement methods.
  • Place bans or regulations on draining intact peatlands, compensate farmers for income losses, and offer extension services that promote protection and paludiculture (growing food on peatlands).
  • Grant Indigenous communities full property rights and autonomy and support them in monitoring, managing, and enforcing protected areas.
  • Incorporate peatland protection into national climate plans and international commitments.
  • Coordinate peatland protection efforts horizontally (e.g., across agencies) and vertically (e.g., across subnational, national, and international efforts), ensuring an inclusive process for local and Indigenous communities.
  • Use financial incentives such as subsidies, tax breaks, and payments for ecosystem services (PES) to protect peatlands from development.
  • Synthesize water management regulations to ensure local authorities, renters, and landowners coordinate sufficient water levels in peatlands.
  • Remove harmful agricultural, logging, and mining subsidies.
  • Map and utilize real-time data to monitor the status and condition of peatland areas.
  • Invest public funds in peatland conservation, restoration, sustainable management practices, specialized research facilities, and other R&D efforts.
  • Invest in fire warning, prevention, and response efforts and establish local volunteer fire prevention groups.
  • Work with farmers, civil society, and businesses to develop high-integrity carbon markets for peatlands.

Further information:

Practitioners
  • Refrain from draining or developing intact peatlands.
  • Invest in peatland conservation, restoration, sustainable management practices, specialized research facilities, and other R&D efforts.
  • Participate in stakeholder engagements and assist policymakers in designating peatlands, creating regulations, and implementing robust monitoring and enforcement methods.
  • Grant Indigenous communities full property rights and autonomy and support them in monitoring, managing, and enforcing protected areas.
  • Ensure protected peatlands don’t displace, violate rights, or reduce access to vital resources for local and Indigenous communities.
  • Assist in managing and monitoring protected peatlands, utilizing real-time monitoring and satellite data.
  • Create sustainable use regulations for protected peatland areas that provide resources to the local community.
  • Conduct proactive land-use planning to avoid infrastructure or development projects that may interfere with protected peatlands or incentivize drainage.
  • Create legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over protected peatlands.
  • Help shift public narratives to mobilize public action and build political will for protecting peatlands by creating educational campaigns and strengthening networks of stakeholders and rightsholders.
  • Take advantage of existing financial incentives such as subsidies, tax breaks, and payments for ecosystem services (PES) to protect peatlands from development.
  • Offer or create market mechanisms such as biodiversity offsets, payments for ecosystem services, voluntary high-integrity carbon markets, and debt-for-nature swaps to fund peatland protection.
  • Synthesize water management regulations to ensure local authorities, renters, and landowners coordinate sufficient water levels in peatlands.
  • Establish coordinating bodies for farmers, landowners, policymakers, and other stakeholders to manage protected areas holistically.
  • Invest in fire warning, prevention, and response efforts and establish local volunteer fire prevention groups.

Further information:

Business Leaders
  • Create peat-free supply chains, utilizing data, information, and the latest technology to inform product sourcing.
  • Integrate peat-free business and investment policies and practices in net zero strategies.
  • Only purchase carbon credits from high-integrity, verifiable carbon markets and do not use them as replacements for decarbonizing operations.
  • Develop financial instruments to invest in peatlands focusing on supporting Indigenous communities.
  • Conduct proactive land-use planning to avoid infrastructure or development projects that may interfere with protected peatlands or incentivize drainage.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Invest in and support Indigenous and local communities' capacity for legal protection and public relations.
  • Leverage political influence to advocate for stronger peatland protection policies at national and international levels. 

Further information:

Nonprofit Leaders
  • Ensure operations utilize peat-free products and supply chains.
  • Advocate for protecting peatlands and for public investments.
  • Assist in managing and monitoring protected peatlands, utilizing real-time monitoring and satellite data.
  • Provide financial support for protecting peatlands management, monitoring, and enforcement.
  • Assist in conducting proactive land-use planning to avoid infrastructure or development projects that may interfere with protected peatlands or incentivize drainage.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over protected peatlands.
  • Support high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Share data, information, and investment frameworks that successfully avoid deforestation to support protected peatlands, businesses, and investors.
  • Help shift public narratives to mobilize public action and build political will for protecting peatlands by creating educational campaigns and strengthening networks of stakeholders and rightsholders.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Invest in and support Indigenous and local communities' capacity for legal protection and public relations.

Further information:

Investors
  • Create peat-free investment portfolios, utilizing data, information, and the latest technology to inform investments.
  • Invest in peatland protection, monitoring, management, and enforcement mechanisms.
  • Utilize financial mechanisms such biodiversity offsets, payments for ecosystem services, voluntary high-integrity carbon markets, and debt-for-nature swaps to fund peatland protection.
  • Invest in and support Indigenous and local communities' capacity for legal protection and public relations.
  • Share data, information, and investment frameworks that successfully avoid investments that drive peatland destruction to support peatlands, other investors, and NGOs.
  • Help shift public narratives to mobilize public action and build political will for protecting peatlands by creating educational campaigns and strengthening networks of stakeholders and rightsholders.

Further information:

Philanthropists and International Aid Agencies
  • Ensure operations utilize peat-free products and supply chains.
  • Advocate for protecting peatlands and for public investments.
  • Provide technical assistance to low- and middle-income countries and communities to protect peatlands.
  • Provide financial assistance to low- and middle-income countries and communities for peatland protection.
  • Assist in managing and monitoring protected peatlands, utilizing real-time monitoring and satellite data.
  • Assist in conducting proactive land-use planning to avoid infrastructure or development projects that may interfere with protected peatlands or incentivize drainage.
  • Support and finance high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over protected peatlands.
  • Support peatlands, other investors, and NGOs by sharing data, information, and investment frameworks that successfully avoid financing peatland destruction.
  • Help shift public narratives to mobilize public action and build political will for protecting peatlands by creating educational campaigns and strengthening networks of stakeholders and rightsholders.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Invest in and support Indigenous and local communities' capacity for legal protection and public relations.
  • Financially support Indigenous land tenure.

Further information:

Thought Leaders
  • Advocate for protecting peatlands and for public investments.
  • Assist in managing and monitoring protected peatlands, utilizing real-time monitoring and satellite data.
  • Assist in conducting proactive land-use planning to avoid infrastructure or development projects that may interfere with protected peatlands or incentivize drainage.
  • Provide technical assistance to low- and middle-income countries and communities to protect peatlands.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over protected peatlands.
  • Support high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Share data, information, and investment frameworks that successfully avoid deforestation to support protected peatlands, businesses, and investors.
  • Help shift public narratives to mobilize public action and build political will for protecting peatlands by creating educational campaigns and strengthening networks of stakeholders and rightsholders.
  • Amplify the voices of local communities and civil society to promote robust media coverage.
  • Support Indigenous and local communities' capacity for legal protection and public relations.

Further information:

Technologists and Researchers
  • Improve mapping of peatland area, carbon content, emissions data, and monitoring methods, utilizing field measurements, models, satellite imagery, and GIS tools.
  • Develop land-use planning tools that help avoid infrastructure or development projects that may interfere with protecting peatlands or incentivize drainage.
  • Create tools for local communities to monitor peatlands, such as mobile apps, e-learning platforms, and mapping tools.
  • Develop verifiable carbon credits using technology such as blockchain to improve the integrity of carbon markets.
  • Develop supply chain tracking software for investors and businesses seeking to create peat-free portfolios and products.

Further information:

Communities, Households, and Individuals
  • Ensure purchases and investments utilize peat-free products and supply chains.
  • Advocate for protecting peatlands and for public investments.
  • Invest in fire warning, prevention, and response efforts and establish local volunteer fire prevention groups.
  • Establish coordinating bodies for farmers, landowners, policymakers, and other stakeholders to manage protected areas holistically.
  • Assist in managing and monitoring protected peatlands, utilizing real-time monitoring and satellite data.
  • Assist in conducting proactive land-use planning to avoid infrastructure or development projects that may interfere with protected peatlands or incentivize drainage.
  • Advocate for creating legal grievance processes, dispute resolution mechanisms, and restitution procedures for violations or disagreements over protected peatlands.
  • Help shift public narratives to mobilize public action and build political will for protecting peatlands by creating educational campaigns and strengthening networks of stakeholders and rightsholders.
  • Support Indigenous and local communities' capacity for legal protections and public relations.

Further information:

Sources
Evidence Base

Consensus of effectiveness in reducing emissions and maintaining carbon removal: High

There is high scientific consensus that protecting peatland carbon stocks is a critical component of mitigating climate change (Girkin & Davidson, 2024; Harris et al., 2022; Leifield et al., 2019; Noon et al., 2022; Strack et al., 2022). Globally, an estimated 11–12% of peatlands have been drained for uses such as agriculture, forestry, and harvesting of peat for horticulture and fuel, with much more extensive degradation in temperate and tropical regions (~45%) than in boreal regions (~4%) (Fluet-Chouinard et al., 2023; Leifield & Menichetti, 2018; UNEP, 2022). Rates of peatland degradation are highly uncertain, and the effectiveness of PAs at reducing drainage remains unquantified. In lieu of peatland-specific data on the effectiveness of PAs at reducing drainage, we used estimates from Wolf et al. (2021), who found that PAs reduce forest loss by approximately 40.5% at the global average. 

Carbon stored in peatlands has been characterized as “irrecoverable carbon” because it takes centuries to millennia to accumulate and could not be rapidly recovered if lost (Goldstein et al., 2020; Noon et al., 2021). Degraded peatlands currently emit an estimated 1.3–1.9 Gt CO₂‑eq/yr (excluding fires), equal to ~2–4% of total global emissions (Leifield and Menichetti., 2018; UNEP, 2022). Leifield et al. (2019) projected that without protection or restoration measures, emissions from drained peatlands could produce enough emissions to consume 10–41% of the remaining emissions budget for keeping warming below 1.5–2.0 °C. Peatland drainage had produced a cumulative 80 Gt CO₂‑eq by 2015, equal to nearly two years worth of total global emissions. In a modeling study, Humpenöder et al. (2020) projected that an additional 10.3 Mha of peatlands would be degraded by 2100 in the absence of new protection efforts, increasing annual emissions from degraded peatlands by ~25% (an additional 0.42 Gt CO₂‑eq/yr  in their study). 

The results presented in this document synthesize findings from 11 global datasets, supplemented by four regional studies on peatland loss rates in Southeast Asia. We recognize that geographic bias in the information underlying global data products creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

Appendix

This analysis quantifies the emissions associated with peatland degradation and their potential reduction via establishment of Protected Areas (PAs). We leveraged multiple data products, including national-scale peatland area estimates, a peatland distribution map, shapefiles of PAs and Indigenous peoples’ lands, available data on rates of peatland degradation by driver, country-scale data on reductions in ecosystem degradation inside of PAs, maps of biomass carbon stocks, and biome-level emissions factors from disturbed peat soils. This appendix describes the source data products and how they were integrated. 

Peatland Extent

The global extent and distribution of peatlands is highly uncertain, and all existing peatland maps have limitations. Importantly, there is no globally accepted definition of a peatland, and different countries and data products use variable thresholds for peat depth and carbon content to define peatlands. The Global Peatland Assessment was a recent comprehensive effort to compile and harmonize existing global peatland area estimates (UNEP, 2022). We rely heavily on two products resulting from this effort: a national-scale dataset of peatland area titled the Global Peatland Database (GPD) and a map of likely peatland areas titled the Global Peatlands Map (GPM; 1 km resolution). 

Scaling Procedures

The GPM represents a known overestimate of the global peatland area, so we scaled area estimates derived from spatially explicit analyses dependent on the GPM to match total areas from the GPD. To develop a map of country-level scaling factors, we first calculated the peatland area within each country from the GPM. We calculated the country-level scaling factors as the country-level GPD values divided by the associated GPM values and converted them to a global raster. Some countries had peatland areas represented in either the GPD or GPM, but not both. Four countries had peatland areas in the GPM that were not present in the GPD, which contained 0.51 Mha of peatlands per the GPM. These areas were left unscaled. There were 38 countries with peatland areas in the GPD that did not have areas in the GPM, containing a total 0.70 Mha of peatlands. These areas, which represented 0.14% of the total peatland area in the GPD, were excluded from the scaled maps. We then multiplied the pixel-level GPM values by the scalar raster. Because of the missing countries, this scaling step very slightly overestimated (by 0.4%) total peatlands relative to the GPD. To account for this, we multiplied this intermediate map by a final global scalar (calculated as the global GPM total divided by the GPD total). This process produced a map with the same peatland distribution as the GPM but a total area that summed to that reported in the GPD.

Exclusion of Coastal Peatlands

Many coastal wetlands have peat soils, though the extent of this overlap has not been well quantified. Coastal wetlands are handled in the Protect Coastal Wetlands solution, so we excluded them from this solution to avoid double-counting. Because of the large uncertainties in both the peatland maps and available maps of coastal wetlands, we were not confident that the overlap between the two sets of maps provided a reliable estimate of the proportion of coastal wetlands located on peat soils. Therefore, we took the conservative approach of excluding all peatland pixels that were touching or overlapping with the coastline. This reduced the total peatland area considered in this solution by 5.33 Mha (1.1%). We additionally excluded degraded peatlands from the adoption ceiling and achievable range using country-level data from the GPD. Degraded peatlands will continue to be emissions sources until they are restored, so protection alone will not confer an emissions benefit.

Total Peatland Area

We conducted the analyses by latitude bands (tropical: –23.4° to 23.4°; subtropical: –35° to –23.4° and 23.4° to 35°; temperate: –35° to –50° and 35° to 50°; boreal: <–50° and >50°) in order to retain some spatial variability in emissions factors and degradation rates and drivers. We calculated the total peatland area within each latitude band based on both the scaled and unscaled peatland maps with coastal pixels excluded. We used these values as the adoption ceiling and for subsequent calculations of protected areas. 

Protected Peatland Areas

We identified protected peatland areas using the World Database on Protected Areas (WDPA, 2024), which contains boundaries for each PA and additional information, including their establishment year and IUCN management category (Ia to VI, not applicable, not reported, and not assigned). For each PA polygon, we extracted the peatland area from the unscaled version of the GPM with coastal pixels removed. 

Each PA was classified into climate zones (described above) based on the midpoint between its minimum and maximum latitude. Then, protected peatland areas were summed to the IUCN class-climate zone level, and the proportion of peatlands protected within each was calculated by dividing the protected area by the unscaled total area in each climate zone. The proportion of area protected was then multiplied by the scaled total area for each zone to calculate adoption in hectares within each IUCN class and climate zone. To evaluate trends in adoption over time, we aggregated protected areas by establishment year as reported in the WDPA. We used the same procedure to calculate the proportion of area protected using the unscaled maps, and then scale for the total area by biome. 

We used the maps of Indigenous people’s lands from Garnett et al. 2018 to identify Indigenous people’s lands that were not inside of established PAs. The total peatland area within Indigenous people’s lands process as above.

Peatland Degradation and Emissions

Broadly, we estimated annual, per-ha emissions savings from peatland protection as the difference between net carbon exchange in a protected peatland versus an unprotected peatland, accounting for all emissions pathways, the drivers of disturbance, the baseline rates of peatland disturbance, and the effectiveness of PAs at reducing ecosystem degradation. In brief, our calculation of the effectiveness of peatland protection followed Equation S1, in which the annual peatland loss avoided due to protection (%/yr) is multiplied by the 30-yr cumulative sum of emissions per ha of degraded peatland (CO₂‑eq /ha over a 30-yr period). These two terms are described in depth in the subsequent sections. 

Equation A1.

\[ Effectiveness = Peatland\text{ }loss_{avoided} \times \sum_{t=1}^{30}{Emissions} \]

Peatland Degradation Rates 

We calculated the avoided rate of peatland loss (%/yr) as the difference between the baseline rate of peatland loss without protection and the estimated rate of peatland loss within PAs (Equation A2), since PAs do not confer complete protection from ecosystem degradation. 

Equation A2.

\[ Peatland\text{ }loss_{avoided} = Peatland\text{ }loss_{baseline} \times Reduction\text{ }in\text{ }loss \]

We compiled baseline estimates of the current rates of peatland degradation from all causes (%/yr) from the existing literature (Table A1). Unfortunately, data on the rate of peatland loss within PAs are not available. However, satellite data have enabled in-depth, global-scale studies of the effectiveness of PAs at reducing tree cover loss. While not all peatlands are forested and degradation dynamics on peatlands can differ from those on forests writ large, these estimates are a reasonable approximation of the effectiveness of PAs at reducing peatland loss. We used the country-level estimates of the proportionate reduction in loss inside versus outside of PAs from Wolf et al. (2021), which we aggregated to latitude bands based on the median latitude of each country (Table A1).

Table A1. Biome-level annual baseline rate of peatland loss, the effectiveness of protection at reducing loss, and the annual avoided rate of peatland loss under protection.

Climate Zone Mean Annual Peatland Loss (%/yr) Proportionate Reduction in Loss Under Protection Avoided Loss Under Protection (%/yr)
Boreal 0.3% 0.44 0.13%
Subtropic 1.2% 0.60 0.73%
Temperate 0.6% 0.56 0.33%
Tropic 1.5% 0.41 0.63%
Left Text Column Width

Emissions Factors for Peatland Degradation

Equation S3 provides an overview of the calculation of emissions from degraded peatlands. In brief, we calculated cumulative emissions as the biomass carbon stock plus the 30-yr total of CO₂‑equivalent fluxes from peat oxidation (Pox), dissolved organic carbon losses (DOC), methane from drainage ditches (Mditch), on-field methane (Mfield), on-field nitrous oxide (N) and the lost net sequestration from an intact peatland, accounting for carbon sequestration in peat and methane emissions from intact peatlands (Seqloss).

Equation A3.

\[ \sum_{t=1}^{30}{Emissions} = Biomass + \sum_{t=1}^{30}{(P_{ox} + DOC + M_{ditch} + M_{field} + N + Seq_{loss})} \]

The IPCC Tier 1 emissions factors for peatland degradation are disaggregated by climate zone (tropical, temperate, and boreal), soil fertility status (nutrient-poor versus nutrient rich), and the driver of degradation (many subclasses of forestry, cropland, grassland, and peat extraction) (IPCC 2014; Tables 2.1–2.5). Table III.5 of Annex III of the Global Peatlands Assessment provides a summarized set of emissions factors based directly on the IPCC values but aggregated to the four coarser classes of degradation drivers listed above (UNEP, 2022), which we use for our analysis. They include the following pathways: CO₂ from peat oxidation, off-site emissions from lateral transport of dissolved organic carbon (DOC), methane emissions from the field and drainage ditches, and nitrous oxide emissions from the field. Particulate organic carbon (POC) losses may be substantial, but were not included in the IPCC methodology due to uncertainties about the fate of transported POC. These emissions factors are reported as annual rates per disturbed hectare, and emissions from these pathways continue over long periods of time.

Three additional pathways that are not included in the IPCC protocol are relevant to the emissions accounting for this analysis: the loss of carbon sequestration potential from leaving the peatland intact, the methane emissions that occur from intact peatlands, and the emissions from removal of the vegetation overlying peat soils. Leifield et al. (2019) reported the annual net carbon uptake per hectare of intact peatlands, including sequestration of carbon in peat minus naturally occurring methane emissions due to the anoxic conditions. If the peatland is not disturbed, these methane emissions and carbon sequestration will persist indefinitely on an annual basis. 

We accounted for emissions from removal of biomass using a separate protocol than emissions occurring from the peat soil due to differences in the temporal dynamics of loss. While all other emissions from peat occur on an annual basis and continue for many decades or longer, emissions from biomass occur relatively quickly. Biomass clearing produces a rapid pulse of emissions from labile carbon pools followed by a declining, but persistent, rate of emissions as more recalcitrant carbon pools decay over subsequent years. The entire biomass carbon stock is likely to be lost within 30 years. Average biomass carbon stocks over the extent of the peatland distribution in the GPM were calculated by latitude band based on the above and below ground biomass carbon stock data from Spawn et al. (2020). We presumed 100% of the biomass carbon stock is lost from peatland degradation, though in many cases some amount of biomass remains following degradation, depending on the terminal land use.

Peatland Degradation Drivers 

Emissions from peatland loss depend on the driver of degradation (e.g., forestry, cropland, peat extraction; IPCC 2014). The GPD contains national-scale estimates of historical peatland loss by driver, which we used to calculate weights for each driver, reflecting the proportion of peatland loss attributable to each driver by latitude band. We took the weighted average of the driver-specific peatland emissions factors, calculated as the sum of the products of the weights and the driver-specific emissions factors.

Appendix References

Garnett, S. T., Burgess, N. D., Fa, J. E., Fernández-Llamazares, Á., Molnár, Z., Robinson, C. J., Watson, J. E. M., Zander, K. K., Austin, B., Brondizio, E. S., Collier, N. F., Duncan, T., Ellis, E., Geyle, H., Jackson, M. V., Jonas, H., Malmer, P., McGowan, B., Sivongxay, A., & Leiper, I. (2018). A spatial overview of the global importance of Indigenous lands for conservation. Nature Sustainability, 1(7), 369–374. https://doi.org/10.1038/s41893-018-0100-6

IPCC Task Force on National Greenhouse Gas Inventories. (2014). 2013 supplement to the 2006 IPCC guidelines for national greenhouse gas inventories: Wetlands (T. Hiraishi, T. Krug, K. Tanabe, N. Srivastava, J. Baasansuren, M. Fukuda, & T. G. Troxler, Eds.). Intergovernmental Panel on Climate Change. https://www.ipcc.ch/site/assets/uploads/2018/03/Wetlands_Supplement_Entire_Report.pdf

Leifeld, J., Wüst-Galley, C., & Page, S. (2019). Intact and managed peatland soils as a source and sink of GHGs from 1850 to 2100. Nature Climate Change, 9(12), 945–947. https://doi.org/10.1038/s41558-019-0615-5

Spawn, S. A., Sullivan, C. C., Lark, T. J., & Gibbs, H. K. (2020). Harmonized global maps of above and belowground biomass carbon density in the year 2010. Scientific Data, 7(1), 112. https://doi.org/10.1038/s41597-020-0444-4

UNEP. (2022). Global peatlands assessment: The state of the world’s peatlands: Evidence for action toward the conservation, restoration, and sustainable management of peatlands. https://www.unep.org/resources/global-peatlands-assessment-2022

UNEP-WCMC and IUCN (2024), Protected Planet: The World Database on Protected Areas (WDPA) and World Database on Other Effective Area-based Conservation Measures (WD-OECM) [Online], Accessed November 2024, Cambridge, UK: UNEP-WCMC and IUCN. Available at: www.protectedplanet.net.

Wolf, C., Levi, T., Ripple, W. J., Zárrate-Charry, D. A., & Betts, M. G. (2021). A forest loss report card for the world’s protected areas. Nature Ecology & Evolution, 5(4), 520–529. https://doi.org/10.1038/s41559-021-01389-0

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