This is a “Highly Recommended” climate solution based on its effectiveness, scalability, and evidence of impact.

Improve Annual Cropping

Submitted by Drawdown Admin on
Sector
FALO & Nature-Based Carbon Removal
Mode
Cut Emissions Remove Carbon
Cluster
Shift Agriculture Practices
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Summary

Farmers on much of the world’s 1.4 billion ha of cropland grow and harvest annual crops – crops like wheat, rice, and soybeans that live for one year or less. After harvest, croplands are often left bare for the rest of the year and sometimes tilled, exposing the soil to wind and rain. This keeps soil carbon levels low and can lead to soil erosion. There are many ways to improve annual cropping to protect or enhance the health of the soil and increase soil organic matter. Project Drawdown’s Improve Annual Cropping solution is a set of practices that protects soils by minimizing plowing (no-till/reduced tillage) and maintaining continuous soil cover (by retaining crop residues or growing cover crops). This increases soil carbon sequestration and reduces nitrous oxide emissions. These techniques are commonly used in conservation agriculture, regenerative, and agro-ecological cropping systems. Other annual cropping practices with desirable climate impacts – including compost application and crop rotations – are omitted here due to lack of data and much smaller scale of adoption. New adoption is estimated from the 2025 level as a baseline which is therefore set to zero.

Extreme weather events,Droughts
Income & work,Food security
Nature protection,Land resources,Water quality
Description for Social and Search
Improve Annual Cropping is a highly recommended climate solution. It enhances the soil’s ability to store carbon and reduces emissions of nitrous oxide, a potent greenhouse gas.
Overview

The Improve Annual Cropping solution incorporates several practices that minimize soil disturbance and introduce a physical barrier meant to prevent erosion to fragile topsoils. Our definition includes two of the three pillars of conservation agriculture: minimal soil disturbance and permanent soil cover (Kassam et al., 2022).

Minimal Soil Disturbance

Soil organic carbon (SOC) – which originates from decomposed plants – helps soils hold moisture and provides the kinds of chemical bonding that allow nutrients to be stored and exchanged easily with plants. Soil health and productivity depend on microbial decomposition of plant biomass residues, which mobilizes critical nutrients in soil organic matter (SOM) and builds SOC. Conventional tillage inverts soil, buries residues, and breaks down compacted soil aggregates. This process facilitates microbial activity, weed removal, and water infiltration for planting. However, tillage can accelerate CO₂ fluxes as SOC is lost to oxidation and runoff. Mechanical disturbance further exposes deeper soils to the atmosphere, leading to radiative absorption, higher soil temperatures, and catalyzed biological processes – all of which increase oxidation of SOC (Francaviglia et al., 2023).

Reduced tillage limits soil disturbance to support increased microbial activity, moisture retention, and stable temperature at the soil surface. This practice can increase carbon sequestration, at least when combined with cover cropping. These effects are highly contextual, depending on tillage intensity and soil depth as well as the practice type, duration, and timing. Reduced tillage further reduces fossil fuel emissions from on-farm machinery. However, this practice often leads to increased reliance on herbicides for weed control (Francaviglia et al., 2023).

Permanent Soil Cover

Residue retention and cover cropping practices aim to provide permanent plant cover to protect and improve soils. This can improve aggregate stability, water retention, and nutrient cycling. Farmers practicing residue retention leave crop biomass residues on the soil surface to suppress weed growth, improve water infiltration, and reduce evapotranspiration from soils (Francaviglia et al., 2023).

Cover cropping includes growth of spontaneous or seeded plant cover, either during or between established cropping cycles. In addition to SOC, cover cropping can help decrease nitrous oxide emissions and bind nitrogen typically lost via oxidation and leaching. Leguminous cover crops can also fix atmospheric nitrogen, reducing the need for fertilizer. Cover cropping can further be combined with reduced tillage for additive SOC and SOM gains (Blanco-Canqui et al., 2015; Francaviglia et al., 2023).

Improved annual cropping practices can simultaneously reduce GHG emissions and improve SOC stocks. However, there are biological limits to SOC stocks – particularly in mineral soils. Environmental benefits are impermanent and only remain if practices continue long term (Francaviglia et al., 2023).

Abdalla, M., Hastings, A., Cheng, K., Yue, Q., Chadwick, D., Espenberg, M., Truu, J., Rees, R. M., & Smith, P. (2019). A critical review of the impacts of cover crops on nitrogen leaching, net greenhouse gas balance and crop productivity. Global Change Biology, 25(8), 2530–2543. Link to source: https://doi.org/10.1111/gcb.14644 

Arslan, A., McCarthy, N., Lipper, L., Asfaw, S., Cattaneo, A., & Kokwe, M. (2015). Climate smart agriculture? Assessing the adaptation implications in Zambia. Journal of Agricultural Economics, 66(3), 753-780. Link to source: https://doi.org/10.1111/1477-9552.12107

Bai, X., Huang, Y., Ren, W., Coyne, M., Jacinthe, P.-A., Tao, B., Hui, D., Yang, J., & Matocha, C. (2019). Responses of soil carbon sequestration to climate-smart agriculture practices: A meta-analysis. Global Change Biology, 25(8), 2591–2606. https://doi.org/10.1111/gcb.14658

Blanco‐Canqui, H., Shaver, T. M., Lindquist, J. L., Shapiro, C. A., Elmore, R. W., Francis, C. A., & Hergert, G. W. (2015). Cover crops and ecosystem services: Insights from studies in temperate soils. Agronomy journal, 107(6), 2449-2474. Link to source: https://doi.org/10.2134/agronj15.0086

Blanco-Canqui, H., & Francis, C. A. (2016). Building resilient soils through agroecosystem redesign under fluctuating climatic regimes. Journal of Soil and Water Conservation, 71(6), 127A-133A. Link to source: https://doi.org/10.2489/jswc.71.6.127A 

Cai, A., Han, T., Ren, T., Sanderman, J., Rui, Y., Wang, B., Smith, P., Xu, M., & Li, Y. (2022). Declines in soil carbon storage under no tillage can be alleviated in the long run. Geoderma, 425, 116028. Link to source: https://doi.org/10.1016/j.geoderma.2022.116028 

Clapp, J. (2021). Explaining growing glyphosate use: The political economy of herbicide-dependent agriculture. Global Environmental Change, 67, 102239. Link to source: https://doi.org/10.1016/j.gloenvcha.2021.102239

Cui, Y., Zhang, W., Zhang, Y., Liu, X., Zhang, Y., Zheng, X., Luo, J., & Zou, J. (2024). Effects of no-till on upland crop yield and soil organic carbon: A global meta-analysis. Plant and Soil, 499(1), 363–377. https://doi.org/10.1007/s11104-022-05854-y

Damania, R., Polasky, S., Ruckelshaus, M., Russ, J., Amann, M., Chaplin-Kramer, R., Gerber, J., Hawthorne, P., Heger, M. P., Mamun, S., Ruta, G., Schmitt, R., Smith, J., Vogl, A., Wagner, F., & Zaveri, E. (2023). Nature's Frontiers: Achieving Sustainability, Efficiency, and Prosperity with Natural Capital. World Bank Publications. Link to source: https://doi.org/10.1596/978-1-4648-1923-0

Francaviglia, R., Almagro, M., & Vicente-Vicente, J. L. (2023). Conservation agriculture and soil organic carbon: Principles, processes, practices and policy options. Soil Systems, 7(1), 17. Link to source: https://doi.org/10.3390/soilsystems7010017 

Griscom, B. W., Adams, J., Ellis, P. W., Houghton, R. A., Lomax, G., Miteva, D. A., Schlesinger, W. H., Shoch, D., Siikamäki, J. V., Smith, P., Woodbury, P., Zganjar, C., Blackman, A., Campari, J., Conant, R. T., Delgado, C., Elias, P., Gopalakrishna, T., Hamsik, M. R., Herrero, M., & Fargione, J. (2017). Natural climate solutions. Proceedings of the National Academy of Sciences, 114(44), 11645-11650. Link to source: https://doi.org/10.1073/pnas.1710465114

Hassan, M. U., Aamer, M., Mahmood, A., Awan, M. I., Barbanti, L., Seleiman, M. F., Bakhsh, G., Alkharabsheh, H. M., Babur, E., Shao, J., Rasheed, A., & Huang, G. (2022). Management strategies to mitigate N2O emissions in agriculture. Life, 12(3), 439. Link to source: https://doi.org/10.3390/life12030439

Hu, Q., Thomas, B. W., Powlson, D., Hu, Y., Zhang, Y., Jun, X., Shi, X., & Zhang, Y. (2023). Soil organic carbon fractions in response to soil, environmental and agronomic factors under cover cropping systems: A global meta-analysis. Agriculture, Ecosystems & Environment, 355, 108591. https://doi.org/10.1016/j.agee.2023.108591

Jat, H. S., Choudhary, K. M., Nandal, D. P., Yadav, A. K., Poonia, T., Singh, Y., Sharma, P. C., & Jat, M. L. (2020). Conservation agriculture-based sustainable intensification of cereal systems leads to energy conservation, higher productivity and farm profitability. Environmental Management, 65(6), 774–786. Link to source: https://doi.org/10.1007/s00267-020-01273-w

Jayaraman, S., Dang, Y. P., Naorem, A., Page, K. L., & Dalal, R. C. (2021). Conservation agriculture as a system to enhance ecosystem services. Agriculture, 11(8), 718. Link to source: https://doi.org/10.3390/agriculture11080718

Kan, Z.-R., Liu, W.-X., Liu, W.-S., Lal, R., Dang, Y. P., Zhao, X., & Zhang, H.-L. (2022). Mechanisms of soil organic carbon stability and its response to no-till: A global synthesis and perspective. Global Change Biology, 28(3), 693–710. https://doi.org/10.1111/gcb.15968

Kassam, A., Friedrich, T., & Derpsch, R. (2022). Successful experiences and lessons from conservation agriculture worldwide. Agronomy, 12(4), 769. https://doi.org/10.3390/agronomy12040769

Lal, R., Smith, P., Jungkunst, H. F., Mitsch, W. J., Lehmann, J., Nair, P. K. R., McBratney, A. B., Sá, J. C. D. M., Schneider, J., Zinn, Y. L., Skorupa, A. L. A., Zhang, H.-L., Minasny, B., Srinivasrao, C., & Ravindranath, N. H. (2018). The carbon sequestration potential of terrestrial ecosystems. Journal of Soil and Water Conservation, 73(6), 145A-152A. Link to source: https://doi.org/10.2489/jswc.73.6.145A

Lessmann, M., Ros, G. H., Young, M. D., & de Vries, W. (2022). Global variation in soil carbon sequestration potential through improved cropland management. Global Change Biology, 28(3), 1162–1177. https://doi.org/10.1111/gcb.15954

Luo, Z., Wang, E., & Sun, O. J. (2010). Can no-tillage stimulate carbon sequestration in agricultural soils? A meta-analysis of paired experiments. Agriculture, Ecosystems & Environment, 139(1), 224–231. https://doi.org/10.1016/j.agee.2010.08.006

Martínez-Mena, M., Carrillo-López, E., Boix-Fayos, C., Almagro, M., García Franco, N., Díaz-Pereira, E., Montoya, I., & De Vente, J. (2020). Long-term effectiveness of sustainable land management practices to control runoff, soil erosion, and nutrient loss and the role of rainfall intensity in Mediterranean rainfed agroecosystems. CATENA, 187, 104352. Link to source: https://doi.org/10.1016/j.catena.2019.104352

Moukanni, N., Brewer, K. M., Gaudin, A. C. M., & O’Geen, A. T. (2022). Optimizing carbon sequestration through cover cropping in Mediterranean agroecosystems: Synthesis of mechanisms and implications for management. Frontiers in Agronomy, 4, 844166. Link to source: https://doi.org/10.3389/fagro.2022.844166 

Mrabet, R., Singh, A., Sharma, T., Kassam, A., Friedrich, T., Basch, G., Moussadek, R., & Gonzalez-Sanchez, E. (2023). Conservation Agriculture: Climate Proof and Nature Positive Approach. In G. Ondrasek & L. Zhang (Eds.), Resource management in agroecosystems. IntechOpen. Link to source: https://doi.org/10.5772/intechopen.108890

Nyagumbo, I., Mupangwa, W., Chipindu, L., Rusinamhodzi, L., & Craufurd, P. (2020). A regional synthesis of seven-year maize yield responses to conservation agriculture technologies in Eastern and Southern Africa. Agriculture, Ecosystems & Environment, 295, 106898. Link to source: https://doi.org/10.1016/j.agee.2020.106898

Ogle, S. M., Alsaker, C., Baldock, J., Bernoux, M., Breidt, F. J., McConkey, B., Regina, K., & Vazquez-Amabile, G. G. (2019). Climate and Soil Characteristics Determine Where No-Till Management Can Store Carbon in Soils and Mitigate Greenhouse Gas Emissions. Scientific Reports, 9(1), 11665. https://doi.org/10.1038/s41598-019-47861-7

Paustian, K., Larson, E., Kent, J., Marx, E., & Swan, A. (2019). Soil C Sequestration as a Biological Negative Emission Strategy. Frontiers in Climate, 1, 8. Link to source: https://doi.org/10.3389/fclim.2019.00008 

Pittelkow, C. M., Liang, X., Linquist, B. A., van Groenigen, K. J., Lee, J., Lundy, M. E., van Gestel, N., Six, J., Venterea, R. T., & van Kessel, C. (2015). Productivity limits and potentials of the principles of conservation agriculture. Nature, 51, 365–368. https://doi.org/10.1038/nature13809

Poeplau, C., & Don, A. (2015). Carbon sequestration in agricultural soils via cultivation of cover crops–A meta-analysis. Agriculture, Ecosystems & Environment, 200, 33–41. Link to source: https://doi.org/10.1016/j.agee.2014.10.024

Powlson, D. S., Stirling, C. M., Jat, M. L., Gerard, B. G., Palm, C. A., Sanchez, P. A., & Cassman, K. G. (2014). Limited potential of no-till agriculture for climate change mitigation. Nature Climate Change, 4(8), 678–683. https://doi.org/10.1038/nclimate2292

Prestele, R., Hirsch, A. L., Davin, E. L., Seneviratne, S. I., & Verburg, P. H. (2018). A spatially explicit representation of conservation agriculture for application in global change studies. Global Change Biology, 24(9), 4038–4053. https://doi.org/10.1111/gcb.14307

Project Drawdown (2020) Farming Our Way Out of the Climate Crisis. Project Drawdown. https://drawdown.org/publications/farming-our-way-out-of-the-climate-crisis

Quintarelli, V., Radicetti, E., Allevato, E., Stazi, S. R., Haider, G., Abideen, Z., Bibi, S., Jamal, A., & Mancinelli, R. (2022). Cover crops for sustainable cropping systems: A review. Agriculture, 12(12), 2076. Link to source: https://doi.org/10.3390/agriculture12122076

Searchinger, T., R. Waite, C. Hanson, and J. Ranganathan. (2019). World Resources Report: Creating a Sustainable Food Future. Washington, DC: World Resources Institute. Link to source: https://research.wri.org/sites/default/files/2019-07/WRR_Food_Full_Report_0.pdf

Stavi, I., Bel, G., & Zaady, E. (2016). Soil functions and ecosystem services in conventional, conservation, and integrated agricultural systems. A review. Agronomy for Sustainable Development, 36(2), 32. Link to source: https://doi.org/10.1007/s13593-016-0368-8

Su, Y., Gabrielle, B., Beillouin, D., & Makowski, D. (2021). High probability of yield gain through conservation agriculture in dry regions for major staple crops. Scientific Reports, 11(1), 3344. Link to source: https://doi.org/10.1038/s41598-021-82375-1

Sun, W., Canadell, J. G., Yu, L., Yu, L., Zhang, W., Smith, P., Fischer, T., & Huang, Y. (2020). Climate drives global soil carbon sequestration and crop yield changes under conservation agriculture. Global Change Biology, 26(6), 3325–3335. Link to source: https://doi.org/10.1111/gcb.15001 

Tambo, J. A., & Mockshell, J. (2018). Differential impacts of conservation agriculture technology options on household income in sub-Saharan Africa. Ecological Economics, 151, 95–105. Link to source: https://doi.org/10.1016/j.ecolecon.2018.05.005

Tiefenbacher, A., Sandén, T., Haslmayr, H.-P., Miloczki, J., Wenzel, W., & Spiegel, H. (2021). Optimizing carbon sequestration in croplands: A synthesis. Agronomy, 11(5), 882. Link to source: https://doi.org/10.3390/agronomy11050882

Toensmeier, E. (2016). The Carbon Farming Solution: A Global Toolkit of Perennial Crops and Regenerative Agriculture Practices for Climate Change Mitigation and Food Security. Green Publishing. Link to source: https://www.chelseagreen.com/product/the-carbon-farming-solution/?srsltid=AfmBOoqsMoY569HfsXOdBsRguOzsDLlRZKOnyM4nyKwZoIALvPoohZlq 

Vendig, I., Guzman, A., De La Cerda, G., Esquivel, K., Mayer, A. C., Ponisio, L., & Bowles, T. M. (2023). Quantifying direct yield benefits of soil carbon increases from cover cropping. Nature Sustainability, 6(9), 1125–1134. https://doi.org/10.1038/s41893-023-01131-7

WCCA (2021). The future of farming: Profitable and sustainable farming with conservation agriculture. 8th World Congress on Conservation Agriculture, Vern Switzerland. Link to source: https://ecaf.org/8wcca

Wooliver, R., & Jagadamma, S. (2023). Response of soil organic carbon fractions to cover cropping: A meta-analysis of agroecosystems. Agriculture, Ecosystems & Environment, 351, 108497. https://doi.org/10.1016/j.agee.2023.108497

Xing, Y., & Wang, X. (2024). Impact of agricultural activities on climate change: a review of greenhouse gas emission patterns in field crop systems. Plants, 13(16), 2285. Link to source: https://doi.org/10.3390/plants13162285

Credits

Lead Fellows

  • Avery Driscoll

  • Erika Luna

  • Megan Matthews, Ph.D.

  • Eric Toensmeier

  • Aishwarya Venkat, Ph.D.

Contributors

  • Ruthie Burrows, Ph.D.

  • James Gerber, Ph.D.

  • Yusuf Jameel, Ph.D.

  • Daniel Jasper

  • Alex Sweeney

Internal Reviewers

  • Aiyana Bodi

  • Emily Cassidy, Ph.D.

  • James Gerber, Ph.D.

  • Hannah Henkin

  • Zoltan Nagy, Ph.D.

  • Ted Otte

  • Paul C. West, Ph.D.

Effectiveness

Based on seven reviews and meta-analyses, which collectively analyzed over 500 studies, we estimate that this solution’s SOC sequestration potential is 1.28 t CO₂‑eq/ha/yr. This is limited to the topsoil (>30 cm), with minimal effects at deeper levels (Sun et al., 2020; Tiefenbacher et al., 2021). Moreover, carbon sequestration potential is not constant over time. The first two decades show the highest increase, followed by an equilibrium or SOC saturation (Cai, 2022; Sun et al., 2020).

The effectiveness of the Improve Annual Cropping solution heavily depends on local geographic conditions (e.g., soil properties, climate), crop management practices, cover crop biomass, cover crop types, and the duration of annual cropping production – with effects typically better assessed in the long term (Abdalla et al., 2019; Francaviglia et al., 2023; Moukanni et al., 2022; Paustian et al., 2019).

Based on reviewed literature (three papers, 18 studies), we estimated that improved annual cropping can potentially reduce nitrous oxide emissions by 0.51 t CO₂‑eq/ha/yr (Table 1). Cover crops can increase direct nitrous oxide emissions by stimulating microbial activity, but – compared with conventional cropping – lower indirect emissions allow for reduced net nitrous oxide emissions from cropland (Abdalla et al., 2019). 

Nitrogen fertilizers drive direct nitrous oxide emissions, so genetic optimization of cover crops to increase nitrogen-use efficiencies and decrease nitrogen leaching could further improve mitigation of direct nitrous oxide emissions (Abdalla et al., 2019). 

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Table 1. Effectiveness at reducing emissions and removing carbon.

Unit: t CO₂‑eq/ha/yr, 100-yr basis

25th percentile 0.29
median (50th percentile) 0.51
75th percentile 0.80

Unit: t CO₂‑eq/ha/yr, 100-yr basis

25th percentile 0.58
median (50th percentile) 1.28
75th percentile 1.72

Unit: t CO₂‑eq/ha/yr, 100-yr basis

25th percentile 0.87
median (50th percentile) 1.79
75th percentile 2.52
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Cost

Because baseline (conventional) annual cropping systems are already extensive and well established, we assume there is no cost to establish new baseline cropland. In the absence of global datasets on costs and revenues of cropping systems, we used data on the global average profit per ha of cropland from Damania et al. (2023) to create a weighted average profit of US$76.86/ha/yr.

Based on 13 data points (of which seven were from the United States), the median establishment cost of the Improve Annual Cropping solution is $329.78/ha. Nine data points (three from the United States) provided a median increase in profitability of US$86.01/ha/yr. 

The net net cost of the Improve Annual Cropping solution is US$86.01. The cost per t CO₂‑eq is US$47.80 (Table 2).

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Table 2. Cost per unit climate impact.

Unit: 2023 US$/t CO₂‑eq, 100-yr basis

median 47.80
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Learning Curve

We found limited information on this solution’s learning curve. A survey of farmers in Zambia found a reluctance to avoid tilling soils because of the increased need for weeding or herbicides and because crop residues may need to be used for livestock feed (Arslan et al., 2015; Searchinger et al., 2019).

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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 Annual Cropping is a DELAYED climate solution. It works more slowly than gradual or emergency brake solutions. Delayed solutions can be robust climate solutions, but it’s important to recognize that they may not realize their full potential for some time.

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Caveats

As with other biosequestration solutions, carbon stored in soils via improved annual cropping is not permanent. It can be lost quickly through a return to conventional agriculture practices like plowing, and/or through a regional shift to a drier climate or other human- or climate change–driven disturbances. Carbon sequestration also only continues for a limited time, estimated at 20–50 years (Lal et al., 2018)).

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Current Adoption

Kassam et al. (2022) provided regional adoption from 2008–2019. We used a linear forecast to project 2025 adoption. This provided a figure of 267.4 Mha in 2025 (Table 3). Note that in Solution Basics in the dashboard we set current adoption at zero. This is a conservative assumption to avoid counting carbon sequestration from land that has already ceased to sequester net carbon due to saturation, which takes place after 20–50 years (Lal et al., 2018).

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Table 3. Current (2025) adoption level.

Unit: Mha of improved annual cropping

Drawdown estimate 267.4
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Adoption Trend

Between 2008–2009 and 2018–2019 (the most recent data available), the cropland area under improved annual cropping practices nearly doubled globally, increasing from 10.6 Mha to 20.5 Mha at an average rate of 1.0 Mha/yr (Kassam et al., 2022), equivalent to a 9.2% annual increase in area relative to 2008–2009 levels. Adoption slowed slightly in the latter half of the decade, with an average increase of 0.8 Mha/yr between 2015–2016 and 2018–2019, equivalent to 4.6% annual increase in area relative to 2015–2016 levels, as shown in Table 4.

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Table 4. 2008–2009 to 2018–2019 adoption trend.

Unit: Mha adopted/yr

mean 9.99
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Adoption Ceiling

Griscom et al. (2017) estimate that 800 Mha of global cropland are suitable – but not yet used for – cover cropping, in addition to 168 Mha already in cover crops (Popelau and Don, 2015). We update the 168 Mha in cover crops to 267 Mha based on Kassam (2022). Griscom et al.’s estimate is based on their analysis that much cropland is unsuitable because it already is used to produce crops during seasons in which cover crops would be grown. Their estimate thus provides a maximum technical potential of 1,067 Mha  by adding 800 Mha of remaining potential to the 267.4 Mha of current adoption (Table 5). 

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Table 5. Adoption ceiling.

Unit: Mha

Adoption ceiling 1,067
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Achievable Adoption

The 8th World Congress on Conservation Agriculture (8WCCA) set a goal to achieve adoption of improved annual cropping on 50% of available cropland by 2050 (WCCA 2021). That provides an Achievable – High of 700 Mha – though this is not a biophysical limit. 

We used the 2008–2019 data from Kassam (2022) to calculate average annual regional growth rates. From these we selected the 25th percentile as our low achievable level (Table 6).

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Table 6. Range of achievable adoption levels.

Unit: Mha

Current Adoption 267.4
Achievable – Low 331.7
Achievable – High 700.0
Adoption Ceiling 1,067

Unit: Mha installed

Current Adoption 0.00
Achievable – Low 64.2
Achievable – High 432.6
Adoption Ceiling 868.6
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Carbon sequestration continues only for a period of decades; because adoption of improved annual cropping was already underway in the 1970s (Kassam et al., 2022), we could not assume that previously adopted hectares continue to sequester carbon indefinitely. Thus we make the conservative choice to calculate carbon sequestration only for newly adopted hectares. We use the same conservative assumption for nitrous oxide emissions. 

Combined effect is 0.0 Gt CO₂‑eq/yr for current adoption, 0.12 for Achievable – Low, 0.78 for Achievable – High, and 1.56 for our Adoption Ceiling.

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Table 8. Climate impact at different levels of adoption.

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.00
Achievable – Low 0.03
Achievable – High 0.22
Adoption Ceiling 0.45

(from nitrous oxide)

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.00
Achievable – Low 0.08
Achievable – High 0.56
Adoption Ceiling 1.12

(from SOC)

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.00
Achievable – Low 0.11
Achievable – High 0.78
Adoption Ceiling 1.57
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Additional Benefits

Extreme Weather Events

The soil and water benefits of this solution can lead to agricultural systems that are more resilient to extreme weather events (Mrabet et al., 2023). These agricultural systems have improved uptake, conservation, and use of water, so they are more likely to successfully cope and adapt to drought, dry conditions, and other adverse weather events (Su et al., 2021). Additionally, more sustained year-round plant cover can increase the capacity of cropping systems to adapt to high temperatures and extreme rainfall (Blanco-Canqui & Francis, 2016; Martínez-Mena et al., 2020).

Droughts

Increased organic matter due to improved annual cropping increases soil water holding capacity. This increases drought resilience (Su et al., 2021). 

Income and Work

Conservation agriculture practices can reduce costs on fuel, fertilizer, and pesticides (Stavi et al., 2016). The highest revenues from improved annual cropping are often found in drier climates. Tambo et al. (2018) found when smallholder farmers in sub-Saharan Africa jointly employed the three aspects of conservation agriculture – reduced tillage, cover crops, and crop rotation – households and individuals saw the largest income gains. Nyagumbo et al. (2020) found that smallholder farms in sub-Saharan Africa using conservation agriculture had the highest returns on crop yields when rainfall was low. 

Food Security

Improved annual cropping can improve food security by increasing the amount and the stability of crop yields. A meta-analysis of studies of South Asian cropping systems found that those following conservation agriculture methods had 5.8% higher mean yield than cropping systems with more conventional agriculture practices (Jat et al., 2020). Evidence supports that conservation agriculture practices especially improve yields in water scarce areas (Su et al., 2021). Nyagumbo et al. (2020) found that smallholder farmers in sub-Saharan Africa experienced reduced yield variability when using conservation agriculture practices.

Nature Protection

Improved annual cropping can increase biodiversity below and above soils (Mrabet et al., 2023). Increased vegetation cover improves habitats for arthropods, which help with pest and pathogen management (Stavi et al., 2016).

Land Resources

Improved annual cropping methods can lead to improved soil health through increased stability of soil structure, increased soil nutrients, and improved soil water storage (Francaviglia et al., 2023). This can reduce soil degradation and erosion (Mrabet et al., 2023). Additionally, more soil organic matter can lead to additional microbial growth and nutrient availability for crops (Blanco-Canqui & Francis, 2016). 

Water Quality

Runoff of soil and other agrochemicals can be minimized through conservation agricultural practices, reducing the amount of nitrate and phosphorus that leach into waterways and contribute to algal blooms and eutrophication (Jayaraman et al., 2021). Abdalla et al. (2019) found that cover crops reduced nitrogen leaching.

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Risks

Herbicides – in place of tillage – are used in many but not all no-till cropping systems to kill (terminate) the cover crop. The large-scale use of herbicides in improved annual cropping systems can produce a range of environmental and human health consequences. Agricultural impacts can include development of herbicide-resistant weeds (Clapp, 2021). 

If cover crops are not fully terminated before establishing the main crop, there is a risk that cover crops can compete with the main crop (Quintarelli et al., 2022). 

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Interactions with Other Solutions

Improved annual cropping has competing interactions with several other solutions related to shifting annual practices. For each of these other solutions, the Improve Annual Cropping solution can reduce the area on which the solution can be applied or the nutrient excess available for improved management. 

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COMPETING

In no-till systems, cover crops are typically terminated with herbicides, often preventing incorporation of trees depending on the type of herbicide used.

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Land managed under the Improve Annual Cropping solution is not available for perennial crops.

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Improved annual cropping typically reduces fertilizer demand, reducing the scale of climate impact under improved nutrient management. 

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Our definition of improved annual cropping requires residue retention, limiting the additional area available for deployment of reduced burning.

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Dashboard

Solution Basics

ha cropland

t CO₂-eq (100-yr)/unit/yr
00.881.8
units
Current 0 06.42×10⁷4.326×10⁸
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0 0.120.78
US$ per t CO₂-eq
48
Delayed

CO₂, N₂O

Trade-offs

Some studies have found that conservation tillage without cover crops can reduce soil carbon stocks in deeper soil layers. They caution against overreliance on no-till as a sequestration solution in the absence of cover cropping. Reduced tillage should be combined with cover crops to ensure carbon sequestration (Luo et al., 2010; Ogle et al., 2019; Powlson et al., 2014).

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t CO2-eq/ha
0400

Thousands of years of agricultural land use have removed nearly 500 Gt CO2-eq from soils

Agriculture has altered the soil carbon balance around the world, resulting in changes (mostly losses) of soil carbon. Much of the nearly 500 Gt CO2-eq lost in the last 12,000 years is now in the atmosphere in the form of CO2.

Sanderman, J. et al. (2017). The soil carbon debt of 12,000 years of human land use [Data set]. PNAS 114(36): 9575–9580. Link to source: https://doi.org/10.1073/pnas.1706103114

t CO2-eq/ha
0400

Thousands of years of agricultural land use have removed nearly 500 Gt CO2-eq from soils

Agriculture has altered the soil carbon balance around the world, resulting in changes (mostly losses) of soil carbon. Much of the nearly 500 Gt CO2-eq lost in the last 12,000 years is now in the atmosphere in the form of CO2.

Sanderman, J. et al. (2017). The soil carbon debt of 12,000 years of human land use [Data set]. PNAS 114(36): 9575–9580. Link to source: https://doi.org/10.1073/pnas.1706103114

Maps Introduction

Adoption of this solution varies substantially across the globe. Currently, improved annual cropping practices are widely implemented in Australia and New Zealand (74% of annual cropland) and Central and South America (69%), with intermediate adoption in North America (34%) and low adoption in Asia, Europe, and Africa (1–5%) (Kassam et al., 2022), though estimates vary (see also Prestele et al., 2018). Future expansion of this solution is most promising in Asia, Africa, and Europe, where adoption has increased in recent years. Large areas of croplands are still available for implementation in these regions, whereas Australia, New Zealand, and Central and South America may be reaching a saturation point, and these practices may be less suitable for the relatively small area of remaining croplands.

The carbon sequestration effectiveness of this solution also varies across space. Drivers of soil carbon sequestration rates are complex and interactive, with climate, initial soil carbon content, soil texture, soil chemical properties (such as pH), and other land management practices all influencing the effectiveness of adopting this solution. Very broadly, the carbon sequestration potential of improved annual cropping tends to be two to three times higher in warm areas than cool areas (Bai et al., 2019; Cui et al., 2024; Lessmann et al., 2022). Warm and humid conditions enable vigorous cover crop growth, providing additional carbon inputs into soils. Complicating patterns of effectiveness, however, arid regions often experience increased crop yields following adoption of this solution whereas humid regions are more likely to experience yield losses (Pittelkow et al., 2015). Yield losses may reduce adoption in humid areas and can lead to cropland expansion to compensate for lower production. 

Uptake of this solution may be constrained by spatial variation in places where cover cropping is suitable. In areas with double or triple cropping, there may not be an adequate interval for growth of a cover crop between harvests. In areas with an extended dry season, there may be inadequate moisture to grow a cover crop.

Action Word
Improve
Solution Title
Annual Cropping
Classification
Highly Recommended
Lawmakers and Policymakers
  • Provide local and regional institutional guidance for improving annual cropping that adapts to the socio-environmental context.
  • Integrate soil protection into national climate mitigation and adaptation plans.
  • Remove financial incentives, such as subsidies, for unsustainable practices and replace them with financial incentives for carbon sequestration practices.
  • Place taxes or fines on emissions and related farm inputs (such as nitrogen fertilizers).
  • Reform international agricultural trade, remove subsidies for emissions-intensive agriculture, and support climate-friendly practices.
  • Strengthen and support land tenure for smallholder farmers.
  • Mandate insurance schemes that allow farmers to use cover crops and reduce tillage.
  • Support, protect, and promote traditional and Indigenous knowledge of land management practices.
  • Set standards for measuring, monitoring, and verifying impacts on SOC accounting for varying socio-environmental conditions.
  • Develop economic budgets for farmers to adopt these practices.
  • Invest in or expand extension services to educate farmers and other stakeholders on the economic and environmental benefits of improved annual cropping.
  • Create, support, or join education campaigns and/or public-private partnerships that facilitate stakeholder discussions.

Further information:

Practitioners
  • Implement no-till practices and use cover crops.
  • Utilize or advocate for financial assistance and tax breaks for farmers to use improved annual cropping techniques.
  • Adjust the timing and dates of the planting and termination of the cover crops in order to avoid competition for resources with the primary crop.
  • Find opportunities to reduce initial operation costs of no-tillage and cover crops, such as selling cover crops as forage or grazing.
  • Take advantage of education programs, support groups, and extension services focused on improved annual cropping methods.
  • Create, support, or join stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.

Further information:

Business Leaders
  • Source from producers implementing improved annual cropping practices, create programs that directly engage and educate farmers, and promote inspiring case studies with the industry and wider public.
  • Create sustainability goals and supplier requirements that incorporate this solution and offer pricing incentives for compliant suppliers.
  • Invest in companies that utilize improved annual cropping techniques or produce the necessary inputs.
  • Promote and develop markets for products that employ improved annual cropping techniques and educate consumers about the importance of the practice.
  • Stay abreast of recent scientific findings and use third-party verification to monitor sourcing practices.
  • Offer financial services – including low-interest loans, micro-financing, and grants – to support low-carbon agriculture (e.g., sustainable land management systems).
  • Support high-integrity carbon markets, institutions, rules, and norms to cultivate the demand for high-quality carbon credits.
  • Create, support, or join education campaigns and/or public-private partnerships that facilitate stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.

Further information:

Nonprofit Leaders
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Conduct and share research on improving annual cropping techniques and local policy options.
  • Advocate to policymakers for improving annual cropping techniques, incentives, and regulations.
  • Educate farmers on sustainable means of agriculture and support implementation.
  • Help integrate improved annual cropping practices as part of the broader climate agenda.
  • Engage with businesses to encourage corporate responsibility and/or monitor soil health.
  • Offer resources and training in financial planning and yield risk management to farmers adopting improved annual cropping approaches.
  • Partner with research institutions and businesses to co-develop and distribute region-specific best practices.
  • Create, support, or join stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.

Further information:

Investors
  • Integrate science-based due diligence on improved annual cropping techniques and soil health measures into all farming and agritech investments.
  • Encourage companies in your investment portfolio to adopt improved annual cropping practices.
  • Offer access to capital, such as low-interest loans, micro-financing, and grants to improve annual cropping.
  • Invest in companies developing technologies that improve annual cropping, such as soil management equipment and related software.
  • Create, support, or join stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.

Further information:

Philanthropists and International Aid Agencies
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Offer access to capital, such as low-interest loans, micro-financing, and grants to support improving annual cropping, (e.g., traditional land management).
  • Conduct and share research on improved annual cropping techniques and local policy options.
  • Advocate to policymakers for improved annual cropping techniques, incentives, and regulations.
  • Educate farmers on traditional means of agriculture and support implementation.
  • Help integrate improved annual cropping practices as part of the broader climate agenda.
  • Engage with businesses to encourage corporate responsibility and/or monitor soil health.
  • Offer resources and training in financial planning and yield risk management to farmers adopting improved annual cropping approaches.
  • Partner with research institutions and businesses to co-develop and distribute region-specific best practices.
  • Create, support, or join stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.
  • Invest in companies developing technologies that improve annual cropping, such as soil management equipment and related software.

Further information:

Thought Leaders
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Conduct and share research on improved annual cropping techniques and local policy options.
  • Advocate to policymakers for improved annual cropping techniques, incentives, and regulations.
  • Educate farmers on traditional means of agriculture and support implementation.
  • Engage with businesses to encourage corporate responsibility and/or monitor soil health.
  • Research the regional impacts of cover crops on SOC and SOM and publish the data.
  • Partner with research institutions and businesses to co-develop and distribute region-specific best practices.
  • Create, support, or join stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.
  • Work with farmers and other private organizations to improve data collection on uptake of improved annual cropping techniques, effectiveness, and regional best practices.

Further information:

Technologists and Researchers
  • Help develop standards for measuring, monitoring, and verifying impacts on SOC accounting for varying socio-environmental conditions.
  • Research the regional impacts of cover crops (particularly outside the United States) on SOC and SOM, and publish the data.
  • Create tracking and monitoring software to support farmers' decision-making.
  • Research the application of AI and robotics for crop rotation.
  • 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 improve annual cropping techniques and provide real-time feedback.

Further information:

Communities, Households, and Individuals
  • Participate in urban agriculture or community gardening programs that implement these practices.
  • Engage with businesses to encourage corporate responsibility and/or monitor soil health.
  • Work with farmers and other private organizations to improve data collection on uptake of improved annual cropping techniques, effectiveness, and regional best practices.
  • Advocate to policymakers for improved annual cropping techniques, incentives, and regulations.
  • Start model farms to demonstrate techniques, conduct experiments, and educate local farmers.
  • Educate farmers on traditional means of agriculture and support implementation.
  • Create, support, or join stakeholder discussions, especially around standardized monitoring frameworks, ROI, and climate benefits.

Further information:

Sources
Evidence Base

Carbon sequestration from cover cropping: High consensus

The impacts of improved annual cropping practices on soil carbon sequestration have been extensively studied, and there is high consensus that adoption of cover crops can increase carbon sequestration in soils. However, estimates of how much carbon can be sequestered vary substantially, and sequestration rates are strongly influenced by factors such as climate, soil properties, time since adoption, and how the practices are implemented.

The carbon sequestration benefits of cover cropping are well established. They have been documented in reviews and meta-analyses including Hu et al. (2023) and Vendig et al. (2023). 

Carbon sequestration from reduced tillage: Mixed

Relative to conventional tillage, estimates of soil carbon gains in shallow soils under no-till management include average increases of 5–20% (Bai et al., 2019; Cui et al., 2024; Kan et al., 2022). Lessmann et al. (2022) estimated that use of no-till is associated with an average annual increase in carbon sequestration of 0.88 t CO₂‑eq /ha/yr relative to high-intensity tillage. 

Nitrous oxide reduction: Mixed

Consensus on nitrous oxide reductions from improved annual cropping is mixed. Several reviews have demonstrated a modest reduction in nitrous oxide from cover cropping (Abdalla et al., 2019; Xing & Wang, 2024). Reduced tillage can result in either increased or decreased nitrous oxide emissions (Hassan et al., 2022). 

The results presented in this document summarize findings from 10 reviews and meta-analyses reflecting current evidence at the global scale. Nonetheless, not all countries are represented. We recognize this limited geographic scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

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Updated Date

Improve Rice Production

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean
Mode
Cut Emissions
Cluster
Shift Agriculture Practices
Image
Peatland
Coming Soon
On
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 reduces methane emissions from rice paddies by converting from continuous flooding to noncontinuous flooding, and reduces the nitrous oxide emissions that result by adopting improved nutrient management as well.
Overview

Rice is a staple crop of critical importance, occupying 11% of global cropland (FAOstat, 1997). Rice production has higher 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.

It is important to first define some terms. 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 it is excluded 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 consider both irrigated and rain-fed paddies.

Methane Reduction

Flooded rice paddies encourage methanogenesis, 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. There are several approaches to reducing 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 results in a significant reduction of 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 application 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 are not included in our analysis at this time. These include the application of biochar to rice paddies and the use of certain 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), 617. Link to source: https://doi.org/10.1038/s41597-023-02526-z

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 

Cheng, H., Shu, K., Zhu, T., Wang, L., Liu, X., Cai, W., Qi, Z., & Feng, S. (2022). Effects of alternate wetting and drying irrigation on yield, water and nitrogen use, and greenhouse gas emissions in rice paddy fields. Journal of Cleaner Production, 349, 131487. Link to source: https://doi.org/10.1016/j.jclepro.2022.131487

Cui, X., Zhou, F., Ciais, P., Davidson, E. A., Tubiello, F. N., Niu, X., Ju, X., Canadell, J.P., Bouwman, A.F., Jackson, R.B., Mueller, N.D., Zheng, X., Kanter, D.R., Tian, H., Adalibieke, W., Bo, Y., Wang, Q., Zhan, X., & Zhu, D. (2021). Global mapping of crop-specific emission factors highlights hotspots of nitrous oxide mitigation. Nature Food, 2(11), 886-893. Link to source: https://doi.org/10.1038/s43016-021-00384-9 

Damania, R., Polasky, S., Ruckelshaus, M., Russ, J., Chaplin-Kramer, R., Gerber, J., Hawthorne, P., Heger, M.P., Mamun, S., Amann, M., Ruta, G., & Wagner, F. (2023). Nature's Frontiers: Achieving Sustainability, Efficiency, and Prosperity with Natural Capital. World Bank Publications. Link to source: https://openknowledge.worldbank.org/entities/publication/855c2e15-c88b-4c04-a2e5-2d98c25b8eca 

Enriquez, Y., Yadav, S., Evangelista, G. K., Villanueva, D., Burac, M. A., & Pede, V. (2021). Disentangling challenges to scaling alternate wetting and drying technology for rice cultivation: Distilling lessons from 20 years of experience in the Philippines. Frontiers in Sustainable Food Systems, 5, 1-16. https://doi.10.3389/fsufs.2021.675818  

Food and Agriculture Organization of the United Nationals. FAOSTAT Statistical Database, [Rome]: FAO, 1997. Link to source: https://www.fao.org/faostat/en/

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

Gu, B., Zhang, X., Lam, S. K., Yu, Y., Van Grinsven, H. J., Zhang, S., Wang, X., Bodirsky, B.L., Wang, S., Duan, J., Ren, C., Bouwman, L., de Vries, W., Xu, J., & 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, A., MacDonald, J.D., Ogle, S.M., Regina, K., van der Weerden, T.J. (2019) 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Chapter 11: N2O Emissions from Managed Soils, and CO2 Emissions from Lime and Urea Application. Cambridge University Press, Cambridge, UK and New York, NY USA. Link to source: https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/4_Volume4/V4_11_Ch11_N2O%26CO2.pdf

Jiang, Y., Carrijo, D., Huang, S., Chen, J., Balaine, N., Zhang, W., Van Groenigen, K.J. & Linquist, B. (2019). Water management to mitigate the global warming potential of rice systems: A global meta-analysis. Field Crops Research, 234, 47–54. Link to source: https://doi.org/10.1016/j.fcr.2019.02.101

Lampayan, R. M., Rejesus, R. M., Singleton, G. R., & Bouman, B. A. (2015). Adoption and economics of alternate wetting and drying water management for irrigated lowland rice. Field Crops Research, 170, 95-108. Link to source: https://doi.org/10.1016/j.fcr.2014.10.013

Li, L., Huang, Z., Mu, Y., Song, S., Zhang, Y., Tao, Y., & Nie, L. (2024). Alternate wetting and drying maintains rice yield and reduces global warming potential: A global meta-analysis. Field Crops Research, 318, 109603. Link to source: https://doi.org/10.1016/j.fcr.2024.109603

Linquist, B. A., Adviento-Borbe, M. A., Pittelkow, C. M., van Kessel, C., & van Groenigen, K. J. (2012). Fertilizer management practices and greenhouse gas emissions from rice systems: a quantitative review and analysis. Field Crops Research, 135, 10-21. Link to source: https://doi.org/10.1016/j.fcr.2012.06.007

Livsey, J., Kätterer, T., Vico, G., Lyon, S. W., Lindborg, R., Scaini, A., Da, C.T,. & Manzoni, S. (2019). Do alternative irrigation strategies for rice cultivation decrease water footprints at the cost of long-term soil health?. Environmental Research Letters, 14(7), 074011. Link to source: https://doi.org/10.1088/1748-9326/ab2108 

Ludemann, C. I., Gruere, A., Heffer, P., & Dobermann, A. (2022). Global data on fertilizer use by crop and by country. Scientific data, 9(1), 1-8. Link to source: https://doi.org/10.1038/s41597-022-01592-z 

Nabuurs, G-J., R. Mrabet, A. Abu Hatab, M. Bustamante, H. Clark, P. Havl.k, J. House, C. Mbow, K.N. Ninan, A. Popp, S. Roe, B. Sohngen, S. Towprayoon, 2022: Agriculture, Forestry and Other Land Uses (AFOLU). In IPCC, 2022: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.009

Ogle, S. M., Wakelin, S. J., Buendia, L., McConkey, B., Baldock, J., Akiyama, H., ... & Zheng, X. (2019). 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Chapter 4: Cropland. Cambridge University Press, Cambridge, UK and New York, NY USA. Link to source: https://www.ipcc.ch/report/2019-refinement-to-the-2006-ipcc-guidelines-for-national-greenhouse-gas-inventories/ 

Qian, H., Zhu, X., Huang, S., Linquist, B., Kuzyakov, Y., Wassmann, R., ... & Jiang, Y. (2023). Greenhouse gas emissions and mitigation in rice agriculture. Nature Reviews Earth & Environment, 4(10), 716-732. Link to source: https://doi.org/10.1038/s43017-023-00482-1 

Raffa, D.W. & Morales-Abubakar, A. L. (2021) Soil Health for Paddy Rice. FAO, Rome. Link to source: https://openknowledge.fao.org/server/api/core/bitstreams/fcd04aae-0389-411b-8a47-a622b23d642f/content 

Roe, S., Streck, C., Beach, R., Busch, J., Chapman, M., Daioglou, V., Deppermann, A., Doelman, J., Emmet-Booth, J., Engelmann, J., Fricko, O., Frischmann, C., Funk, J., Grassi, G., Griscom, B., Havlik, P., Hanssen, S., Humpenöder, F., Landholm, D., LOmax, G., Lehmann, J., Mesnildrey, L., Nabuurrs, G., Popp, A., Rivard, C., Sanderman, J., Sohngen, B., Smith, P., Stehfest, E., Woolf, D., & Lawrence, D. (2021). Land‐based measures to mitigate climate change: Potential and feasibility by country. Global Change Biology, 27(23), 6025-6058. Link to source: https://doi.org/10.1111/gcb.15873

Salmon, J. M., Friedl, M. A., Frolking, S., Wisser, D., & Douglas, E. M. (2015). Global rain-fed, irrigated, and paddy croplands: A new high resolution map derived from remote sensing, crop inventories and climate data. International Journal of Applied Earth Observation and Geoinformation, 38, 321-334. Link to source: https://doi.org/10.1016/j.jag.2015.01.014

Surendran, U., Raja, P., Jayakumar, M., & Subramoniam, S. R. (2021). Use of efficient water saving techniques for production of rice in India under climate change scenario: A critical review. Journal of Cleaner Production, 309. Link to source: https://doi.org/10.1016/j.jclepro.2021.127272

Xia, L., Lam, S. K., Chen, D., Wang, J., Tang, Q., & Yan, X. (2017). Can knowledge‐based N management produce more staple grain with lower greenhouse gas emission and reactive nitrogen pollution? A meta‐analysis. Global change biology, 23(5), 1917-1925. Link to source: https://doi.org/10.1111/gcb.13455

Zhang, Y., Wang, W., Li, S., Zhu, K., Hua, X., Harrison, M.T., Liu, K., Yang, J., Liu, L, & Chan, Y. (2023). Integrated management approaches enabling sustainable rice production under alternate wetting and drying irrigation. Agricultural Water Management, 281. Link to source: https://doi.org/10/1016/j.agwat.2023.108265. 

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 the 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 1).

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 (see “nitrous oxide emissions”). 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 combined effectiveness of noncontinuous flooding and nutrient management for each country with over 100,000 ha of rice production was –0.48–0.09 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).

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

Methane & Nitrous Oxide Reductions by Country
Methane & Nitrous Oxide Reduction (t CO2-eq/ha/yr)
Country methane reduction, t CO2-eq/ha/yr nitrous oxide reduction, t CO2-eq/ha/yr Combined effectiveness, t CO2-eq/ha/yr
Afghanistan1.63 (4.75)0.03 (0.03)1.67 (4.78)
Argentina2.70 (7.85)0.07 (0.07)2.77 (7.93)
Bangladesh1.63 (4.75)0.06 (0.06)1.69 (4.81)
Benin2.30 (6.71)0.03 (0.03)2.34 (6.74)
Bolivia (Plurinational State of)2.70 (7.85)0.00 (0.00)2.70 (7.85)
Brazil2.70 (7.85)0.00 (0.00)2.70 (7.86)
Burkina Faso2.30 (6.71)–0.02 (0.02)2.28 (6.68)
Cambodia2.13 (6.21)0.01 (0.01)2.15 (6.22)
Cameroon2.30 (6.71)0.00 (0.00)2.30 (6.71)
Chad2.30 (6.71)0.01 (0.01)2.32 (6.72)
China2.48 (7.20)0.01 (0.01)2.48 (7.21)
Colombia2.70 (7.85)–0.07 (–0.07)2.63 (7.21)
Côte d'Ivoire2.30 (6.71)0.02 (0.02)2.32 (6.73)
Democratic People's Republic of Korea2.48 (7.20)0.02 (0.02)2.50 (7.23)
Democratic Republic of the Congo2.30 (6.71)0.01 (0.01)2.31 (6.71)
Dominican Republic2.70 (7.85)–0.16 (0.16)2.54 (7.69)
Ecuador2.70 (7.85)–0.08 (–0.08)2.62 (7.77)
Egypt2.30 (6.71)–0.15 (–0.15)2.16 (6.56)
Ghana2.30 (6.71)0.05 (0.05)2.35 (6.76)
Guinea2.30 (6.71)0.01 (0.01)2.32 (6.72)
Guinea-Bissau2.30 (6.71)0.01 (0.01)2.32 (6.72)
Guyana2.70 (7.85)–0.06 (–0.06)2.63 (7.79)
India1.63 (4.75)–0.02 (–0.02)1.61 (4.73)
Indonesia2.13 (6.21)0.11 (011)2.24 (6.31)
Iran (Islamic Republic of)3.29 (9.57)–0.05 (–0.05)3.24 (9.52)
Italy3.29 (9.57)0.00 (0.00)3.29 (9.57)
Japan2.48 (7.20)0.07 (0.07)2.54 (7.27)
Lao People's Democratic Republic2.13 (6.21)0.02 (0.02)2.15 (6.23)
Liberia2.30 (6.71)0.02 (0.02)2.32 (6.72)
Madagascar2.30 (6.71)0.00 (0.00)2.31 (6.71)
Malaysia2.13 (6.21)–0.01 (–0.01)2.13 (6.20)
Mali2.30 (6.71)–0.03 (–0.03)2.28 (6.20)
Mozambique2.30 (6.71)0.01 (0.01)2.32 (6.72)
Myanmar2.13 (6.21)0.04 (0.04)2.17 (6.25)
Nepal1.63 (4.75)0.04 (0.04)1.67 (4.79)
Nigeria2.30 (6.71)0.01 (0.01)2.32 (6.72)
Pakistan1.63 (4.75)–0.04 (–0.04)1.59 (4.71)
Paraguay2.70 (7.85)0.01 (0.01)2.71 (7.86)
Peru2.70 (7.85)0.09 (0.09)2.79 (7.95)
Philippines2.13 (6.21)0.00 (0.00)2.14 (6.21)
Republic of Korea2.48 (7.20)0.00 (0.00)2.47 (7.20)
Russian Federation3.29 (9.57)0.04 (0.04)3.33 (9.61)
Senegal2.30 (6.71)–0.04 (–0.04)2.27 (6.67)
Sierra Leone2.30 (6.71)0.02 (0.02)2.32 (6.73)
Sri Lanka1.63 (4.75)0.02 (0.02)1.65 (4.77)
Thailand2.13 (6.21)–0.03 (–0.03)2.10 (6.18)
Turkey3.29 (9.57)0.10 (0.10)3.39 (9.67)
Uganda2.30 (6.71)0.00 (0.00)2.31 (6.71)
United Republic of Tanzania2.30 (6.71)0.04 (0.04)2.35 (6.75)
United States of America1.55 (4.51)–0.05 (–0.05)1.49 (4.45)
Uruguay2.70 (7.85)0.03 (0.03)2.72 (7.88)
Venezuela (Bolivarian Republic of)2.70 (7.85)–0.48 (–0.48)2.22 (7.38)
Vietnam2.13 (6.21)0.00 (0.00)2.13 (6.20)

Unit: t CO₂‑eq (100-yr, with 20-yr in parentheses)/ha installed/yr

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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-ha 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.

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

Unit: US$/ha

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/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/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
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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 over-application of fertilizer. Here we used the mean value from Gu et al. (2023), a savings of US$507.80/t nitrogen. We used our national-level data on over-application 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.

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Table 3. Net cost and profit of noncontinuous flooding with nutrient management by region in 2023 US$/ha/yr.

Unit: US$/ha

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
Viet Nam 0.00

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 –US$15.03/t CO₂‑eq (Table 4). Note that this cost is the same for both 100- and 20-yr results.

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Table 4. Weighted average cost per unit climate impact.

Unit: US$ (2023) per t CO₂‑eq

Weighted average -15.03
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Learning Curve

Learning curve data are not available for improved rice cultivation.

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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.

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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.

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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). 

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Table 5. Current adoption level (2025).

Unit: Mha

mean 46.65

Noncontinuous flooding, ha installed.

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Nutrient Management

Nutrient management adoption is based 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 provides a national average overapplication rate.

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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.

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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 applied national adoption ceilings for noncontinuous flooding from Bo et al. (2022) to the total national paddy area to determine maximum hectares 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).

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

Unit: Mha

median 77.53

ha of noncontinuous flooding installed.

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Achievable Adoption

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 53.15 Mha. 

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

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Table 8. Range of achievable adoption levels.

Unit: Mha

Current Adoption 48.65
Achievable – Low 53.51
Achievable – High 77.53
Adoption Ceiling 77.53

Mha of noncontinuous flooding installed. 

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We calculated the potential impact of improved rice, on a 100-yr basis, at 0.10 Gt CO₂‑eq/yr from current adoption, and 0.11, 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, 0.31, 0.48, and 0.48, respectively.

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Table 9. Climate impact at different levels of adoption.

Unit: Gt CO₂‑eq/yr

Current Adoption 0.10
Achievable – Low 0.11
Achievable – High 0.16
Adoption Ceiling 0.16

Unit: Gt CO₂‑eq/yr

Current Adoption 0.29
Achievable – Low 0.31
Achievable – High 0.48
Adoption Ceiling 0.48
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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.

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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 mitigated 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 mitigate 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 (Liang et al., 2013; Singh & Craswell, 2021). 

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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). 

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Interactions with Other Solutions

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

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Dashboard

Solution Basics

t CO₂-eq (100-yr)/unit
units
Current 0
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.1 0.10.16
US$ per t CO₂-eq
-15
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.

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% of area
0100

Cultivated areas of paddy rice, 2020

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., and Herrero, M. (2025). Mapping greenhouse gas emissions from global cropland circa 2020 [Data set, PREPRINT Version 1]. In review at Nature Communication. 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., and 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

Cultivated areas of paddy rice, 2020

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., and Herrero, M. (2025). Mapping greenhouse gas emissions from global cropland circa 2020 [Data set, PREPRINT Version 1]. In review at Nature Communication. 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., and 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

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.

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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.

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Improve Nutrient Management

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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. 

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Description for Social and Search
Improve Nutrient Management is a Highly Recommended climate solution. Applying the right amount and type of fertilizers, at the right time, reduces harmful nitrous oxide emissions while also ensuring that crops get the 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 Increase 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 Management solution instead. 

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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 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). 

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Table 1. Effectiveness at reducing emissions.

Unit: t CO₂‑eq /tN, 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).

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

Unit: 2023 US$/t CO₂‑eq

mean -85.21
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Methods and Supporting Data

Abatzoglou, J. T., Dobrowski, S. Z., Parks, S. A., & Hegewisch, K. C. (2018). TerraClimate, a high-resolution global dataset of monthly climate and climatic water balance from 1958–2015. Scientific Data, 5(1), 170191. https://doi.org/10.1038/sdata.2017.191

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. https://doi.org/10.1038/s41597-023-02526-z

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. https://doi.org/10.1038/s43016-023-00913-8 

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.)].

Mehta, P., Siebert, S., Kummu, M., Deng, Q., Ali, T., Marston, L., Xie, W., & Davis, K. F. (2024). Half of twenty-first century global irrigation expansion has been in water-stressed regions. Nature Water, 2(3), 254–261. https://doi.org/10.1038/s44221-024-00206-9

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.

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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.

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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.

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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 t 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 N/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.

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Table 3. Current (2020) adoption level.

Unit: tN/yr

estimate 10,450,000
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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.

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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.

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Table 4. Adoption ceiling.

Unit: tN/yr

estimate 105,580,000
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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.

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Table 5. Range of achievable adoption levels.

Unit: tN/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.

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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). 

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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.

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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.

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Interactions with Other Solutions

Reinforcing

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

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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

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

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Dashboard

Solution Basics

t avoided excess nitrogen application

t CO₂-eq (100-yr)/unit
04.26
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
01

The Problem — Emissions of Nitrous Oxide Coming from Over-fertilized Soils

The world’s agricultural lands can emit high levels of nitrous oxide (N2O), 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
01

The Problem — Emissions of Nitrous Oxide Coming from Over-fertilized Soils

The world’s agricultural lands can emit high levels of nitrous oxide (N2O), 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

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.

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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.

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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
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Updated Date

Protect Coastal Wetlands

Submitted by Drawdown Admin on
Sector
Food, Agriculture, Land & Ocean
Mode
Cut Emissions
Cluster
Protect & Manage Ecosystems
Image
Peatland
Coming Soon
On
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
Nature protection,Water quality
Description for Social and Search
Protect Coastal Wetlands is a Highly Recommended climate solution. By legally protecting mangroves, salt marshes, and seagrasses, it helps preserve existing carbon stocks and avoid 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). 

INSERT FIGURE 1 HERE

These ecosystems are also efficient at trapping carbon suspended in water, which can comprise up to 50% of the carbon sequestered in the system (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, 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 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).

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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 lossbaseline ✕ Reduction in loss)* (Carbonavoided emissions + Carbonsequestration ) 

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%. 

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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. 

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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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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.

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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.

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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, which is related but not necessarily relevant to our analysis, is whether coastal wetlands would have been protected in the absence of carbon financing, which could be important if protection efforts expand and seek carbon credits as many coastal 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.

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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 3a. Current extent of mangrove 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 (Million ha protected).

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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 3, left). Salt marsh ecosystems have the lowest absolute rate of coastal wetland protection expansion (Figure 3a), 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).

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

Unit: ha/yr protected

25th percentile 23,000
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.

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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. 

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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.

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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).

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).

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 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 (Commonwealth of Australia, 2016; Matthews & 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).

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).

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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.

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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). 

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Reducing food loss and waste and improving diets reduce demand for agricultural land. These solutions reduce pressure to convert coastal wetlands to agricultural use, easing expansion of PAs.

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Competing

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

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Dashboard

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
07.647.88
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 0.06
US$ per t CO₂-eq
1
Emergency Brake

CO₂

Solution Basics

ha protected

t CO₂-eq (100-yr)/unit/yr
04.384.78
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
03.153.56
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.

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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 sequestering carbon from coastal wetlands: 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.

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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 section 1. 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 S1). 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 S1.

Wetland lossavoided = Wetland lossbaseline ✕ Reduction in 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 S2) and carbon sequestration rates (30-yr time horizon; Equation S3) 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 S2.

Avoided emissions = Wetland lossavoided t=130(Emissions)

Equation S3.

Sequestration = Wetland lossavoided t=130(Sequestration)

We then estimated effectiveness (Equation S4) 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 S4.

Effectiveness = (Wetland lossavoided) * (Carbonavoided emissions+ Carbonsequestration) 

Finally, we calculated climate impact (Equation S5) by multiplying the adoption area under consideration by the estimated effectiveness from Equation S4.

Equation S5.

Climate Impact = (Effectiveness) * (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

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