This solution meets all of Project Drawdown’s criteria for global climate solutions.

Mobilize Electric Buses

Submitted by Drawdown Admin on
Sector
Transportation
Mode
Cut Emissions
Cluster
Fuel Switching
Image
Peatland
Coming Soon
On
Description for Social and Search
Mobilize Electric Buses is a Highly Recommended climate solution.
Solution in Action
Speed of Action
Caveats
Risks
Consensus
Trade-offs
Action Word
Mobilize
Solution Title
Electric Buses
Classification
Highly Recommended
Lawmakers and Policymakers
Practitioners
Business Leaders
Nonprofit Leaders
Investors
Philanthropists and International Aid Agencies
Thought Leaders
Technologists and Researchers
Communities, Households, and Individuals

Increase Urban Vegetation

Submitted by Drawdown Admin on
Sector
Buildings & Electricity
Cluster
Enhance Efficiency
Image
Peatland
Coming Soon
On
Description for Social and Search
Increase Urban Vegetation is a Highly Recommended climate solution.
Solution in Action
Methods and Supporting Data

Methods and Supporting Data

Speed of Action
Caveats
Risks
Consensus
Trade-offs
Action Word
Increase
Solution Title
Urban Vegetation
Classification
Highly Recommended
Lawmakers and Policymakers
Practitioners
Business Leaders
Nonprofit Leaders
Investors
Philanthropists and International Aid Agencies
Thought Leaders
Technologists and Researchers
Communities, Households, and Individuals

Deploy Agrivoltaics

Submitted by Drawdown Admin on
Sector
Electricity
Mode
Cut Emissions
Cluster
Shift Production
Image
Peatland
Coming Soon
On
Description for Social and Search
The Deploy Agrivoltaics solution is coming soon.
Solution in Action
Methods and Supporting Data

Methods and Supporting Data

Speed of Action
Caveats
Additional Benefits
Risks
Consensus
Trade-offs
Action Word
Deploy
Solution Title
Agrivoltaics
Classification
Highly Recommended
Updated Date

Produce Biochar

Submitted by Drawdown Admin on
Sector
Industrial Carbon Removal
Mode
Remove Carbon
Cluster
Biomass Carbon Removal & Storage
Image
Biochar
Coming Soon
On
Description for Social and Search
The Produce Biochar solution is coming soon.
Methods and Supporting Data

Methods and Supporting Data

Action Word
Produce
Solution Title
Biochar
Classification
Highly Recommended
Updated Date

Deploy Biomass Crops on Degraded Land

Submitted by Drawdown Admin on
Sector
Nature-Based Carbon Removal
Mode
Remove Carbon
Cluster
Use Degraded Land
Image
Tree plantation
Coming Soon
On
Description for Social and Search
The Deploy Biomass Crops on Degraded Land solution is coming soon.
Methods and Supporting Data

Methods and Supporting Data

Action Word
Deploy
Solution Title
Biomass Crops on Degraded Land
Classification
Highly Recommended
Updated Date

Restore Abandoned Farmland

Submitted by Drawdown Admin on
Sector
Nature-Based Carbon Removal
Mode
Remove Carbon
Cluster
Use Degraded Land
Image
Peatland
Coming Soon
On
Description for Social and Search
The Restore Abandoned Farmland solution is coming soon.
Methods and Supporting Data

Methods and Supporting Data

Action Word
Restore
Solution Title
Abandoned Farmland
Classification
Highly Recommended
Updated Date

Deploy Silvopasture

Submitted by Drawdown Admin on
Sector
Nature-Based Carbon Removal
Mode
Remove Carbon
Cluster
Shift Agriculture Practices
Image
Cows grazing among trees
Coming Soon
Off
Summary

We define the Deploy Silvopasture solution as the adoption of agroforestry practices that add trees to grazing land, including planted pastures and natural rangelands. (Note that this solution does NOT include creating forested grazing land by thinning existing forest; this is a form of deforestation and not desirable in terms of climate.) Some silvopastures are open savannas, while others are dense, mature tree plantations. The trees may be planted or managed to naturally regenerate. Some silvopasture systems have been practiced for thousands of years, while others have been recently developed. All provide shade to livestock; in some systems, the trees feed livestock, produce timber or crops for human consumption, or provide other benefits. New adoption is estimated from the 2025 level as a baseline which is therefore set to zero.

Income & work,Food security
Nature protection,Animal well-being,Water quality
Description for Social and Search
Deploy Silvopasture is a Highly Recommended climate solution. It enhances carbon storage by adding trees to grazing land, including planted pastures and natural rangelands.
Overview

In silvopasture systems, trees are planted or allowed to naturally regenerate on existing pasture or rangeland. Tree density is generally less than forest, allowing sunlight through for good forage growth.

Silvopasture has multiple climate impacts, though carbon sequestration is the only one which has been thoroughly studied across all climates and sub-practices.

Silvopasture sequesters carbon in both soil and woody biomass. Carbon sequestration rates are among the highest of any farming system (Toensmeier, 2017). The lifetime accumulation of carbon in both soils and biomass is higher than for managed grazing alone (Montagnini et al., 2019; Nair et al., 2012).

Silvopasture can also reduce GHG emissions, though not in every case. We do not include emissions reductions in this analysis.

Conversion from pasture to silvopasture slightly increases capture and storage of methane in soils (Bentrup and Shi, in press). In addition, in fodder subtypes of silvopasture systems, ruminant livestock consume tree leaves or pods. Many, but not all, of the tree species used in these systems have tannin content that reduces emissions of methane from enteric fermentation (Jacobsen et al., 2019). 

Some subtypes of silvopasture reduce nitrous oxide emissions from manure and urine, as grasses and trees capture nitrogen that microbes would otherwise convert to nitrous oxide. There are also reductions to nitrous oxide emissions from soils: 76–95% in temperate silvopastures and 16–89% in tropical-intensive silvopastures (Ansari et al., 2023; Murguietio et al., 2016).

Many silvopasture systems increase productivity of milk and meat. Yield increases can reduce emissions from deforestation by growing more food on existing farmland, but in some cases can actually worsen emissions if farmers clear forests to adopt the profitable practice (Intergovernmental Panel on Climate Change [IPCC], 2019). The yield impact of silvopasture varies with tree density, climate, system type, and whether the yields of other products (e.g., timber) are counted as well (Rojas et al., 2022). 

Ansari, J., Udawatta, R. P., & Anderson, S. H. (2022). Soil nitrous oxide emission from agroforestry, rowcrop, grassland and forests in North America: a review. Agroforestry Systems, 97(8), 1465–1479. Link to source: https://doi.org/10.1007/s10457-023-00870-y

Basche, A., Tully, K., Álvarez-Berríos, N. L., Reyes, J., Lengnick, L., Brown, T., Moore, J. M., Schattman, R. E., Johnson, L. K., & Roesch-McNally, G. (2020). Evaluating the untapped potential of US conservation investments to improve soil and environmental health. Frontiers in Sustainable Food Systems, 4, 547876. Link to source: https://doi.org/10.3389/fsufs.2020.547876 

Batcheler, M., Smith, M. M., Swanson, M. E., Ostrom, M., & Carpenter-Boggs, L. (2024). Assessing silvopasture management as a strategy to reduce fuel loads and mitigate wildfire risk. Scientific Reports, 14(1), 5954. Link to source: https://doi.org/10.1038/s41598-024-56104-3

Bentrup, G. & Shi, X. (in press). Multifunctional buffers: Design guidelines for buffers, corridors and greenways. USDA Forest Service. 

Bostedt, G., Hörnell, A., & Nyberg, G. (2016). Agroforestry extension and dietary diversity–an analysis of the importance of fruit and vegetable consumption in West Pokot, Kenya. Food Security, 8, 271–284. Link to source: https://doi.org/10.1007/s12571-015-0542-x

Briske, D. D., Vetter, S., Coetsee, C., & Turner, M. D. (2024). Rangeland afforestation is not a natural climate solution. Frontiers in Ecology and the Environment. Link to source: https://doi.org/10.1002/fee.2727

Cadavid, Z., & BE, S. T. (2020). Sistemas silvopastoriles: aspectos teóricos y prácticos. CIPAV. Link to source: https://cipav.org.co/sdm_downloads/sistemas-silvopastoriles-aspectos-teoricos-y-practicos/

Cardinael, R., Umulisa, V., Toudert, A., Olivier, A., Bockel, L., & Bernoux, M. (2019). Revisiting IPCC Tier 1 coefficients for soil organic and biomass carbon storage in agroforestry systems. Environmental Research Letters, 13(12), 124020. Link to source: https://doi.org/10.1088/1748-9326/aaeb5f

Chapman, M., Walker, W.S., Cook-Patton, S.C., Ellis, P.W., Farina, M., Griscom, B.W., & Baccani, A. (2019). Large climate mitigation potential from adding trees to agricultural lands Global Change Biology, 26(80), 4357–4365. Link to source: https://doi.org/10.1111/gcb.15121

Chatterjee, N., Nair, P. R., Chakraborty, S., & Nair, V. D. (2018). Changes in soil carbon stocks across the forest-agroforest-agriculture/pasture continuum in various agroecological regions: A meta-analysis. Agriculture, ecosystems & environment, 266, 55–67. Link to source: https://doi.org/10.1016/j.agee.2018.07.014

Damania, Richard; Polasky, Stephen; Ruckelshaus, Mary; Russ, Jason; Amann, Markus; Chaplin-Kramer, Rebecca; Gerber, James; Hawthorne, Peter; Heger, Martin Philipp; Mamun, Saleh; Ruta, Giovanni; Schmitt, Rafael; Smith, Jeffrey; Vogl, Adrian; Wagner, Fabian; Zaveri, Esha. (2023). Nature's Frontiers: Achieving Sustainability, Efficiency, and Prosperity with Natural Capital. Environment and Sustainable Development series. Washington, DC: World Bank Link to source: https://hdl.handle.net/10986/39453

de Sherbinin, A., VanWey, L. K., McSweeney, K., Aggarwal, R., Barbieri, A., Henry, S., Hunter, L. M., Twine, W., & Walker, R. (2008). Rural household demographics, livelihoods and the environment. Global Environmental Change, 18(1), 38–53. Link to source: https://doi.org/10.1016/j.gloenvcha.2007.05.005

Den Herder, M., Moreno, G., Mosquera-Losada, R. M., Palma, J. H., Sidiropoulou, A., Freijanes, J. J. S., & Burgess, P. J. (2017). Current extent and stratification of agroforestry in the European Union. Agriculture, Ecosystems & Environment, 241, 121–132. Link to source: https://doi.org/10.1016/j.agee.2017.03.005

Di Prima, S., Wright, E. P., Sharma, I. K., Syurina, E., & Broerse, J. E. W. (2022). Implementation and scale-up of nutrition-sensitive agriculture in low- and middle-income countries: A systematic review of what works, what doesn’t work and why. Global Food Security, 32, 100595. Link to source: https://doi.org/10.1016/j.gfs.2021.100595

deStefano, A, & Jacobson, M.G. (2018). Soil carbon sequestration in agroforestry systems: A review. Agroforestry Systems, 92, 285–299. Link to source: https://doi.org/10.1007/s13593-014-0212-y

Dudley, N., Eufemia, L., Fleckenstein, M., Periago, M. E., Petersen, I., & Timmers, J. F. (2020). Grasslands and savannahs in the UN Decade on Ecosystem Restoration. Restoration Ecology, 28(6), 1313–1317. Link to source: https://doi.org/10.1111/rec.13272

Dupraz, C, and Liagre, F.(2011). Agroforesterie: Des Arbres et des Cultures. Editions France Agricole. Link to source: https://agroboutique.com/agroecologie-catalogue/12-agroforesterie-des-arbres-et-des-cultures.html

FAO Statistical Service (2024). FAOStat. Link to source: https://www.fao.org/faostat/en/

Feliciano, D., Ledo, A., Hillier, J., & Nayak, D. R. (2018). Which agroforestry options give the greatest soil and above ground carbon benefits in different world regions?. Agriculture, ecosystems & environment, 254, 117–129. Link to source: https://doi.org/10.1016/j.agee.2017.11.032

Frelat, R., Lopez-Ridaura, S., Giller, K. E., Herrero, M., Douxchamps, S., Djurfeldt, A. A., Erenstein, O., Henderson, B., Kassie, M., Paul, B. K., Rigolot, C., Ritzema, R. S., Rodriguez, D., Van Asten, P. J. A., & Van Wijk, M. T. (2016). Drivers of household food availability in sub-Saharan Africa based on big data from small farms. Proceedings of the National Academy of Sciences of the United States of America, 113(2), 458–463. Link to source: https://doi.org/10.1073/pnas.1518384112

Garrett, H. E., Kerley, M. S., Ladyman, K. P., Walter, W. D., Godsey, L. D., Van Sambeek, J. W., & Brauer, D. K. (2004). Hardwood silvopasture management in North America. In New Vistas in Agroforestry: A Compendium for 1st World Congress of Agroforestry, 2004 (pp. 21–33). Springer Netherlands. Link to source: https://doi.org/10.1007/978-94-017-2424-1_2

Goracci, J., & Camilli, F. (2024). Agroforestry and animal husbandry. IntechOpen. Link to source: https://doi.org/10.5772/intechopen.1006711

Government of Colombia (2020). Actualización de la Contribución Determinada a Nivel Nacional de Colombia. Government of Colombia. Link to source: https://unfccc.int/sites/default/files/NDC/2022-06/NDC%20actualizada%20de%20Colombia.pdf

Greene, H., Kazanski, C. E., Kaufman, J., Steinberg, E., Johnson, K., Cook-Patton, S. C., & Fargione, J. (2023). Silvopasture offers climate change mitigation and profit potential for farmers in the eastern United States. Frontiers in Sustainable Food Systems, 7, 1158459. Link to source: https://doi.org/10.3389/fsufs.2023.1158459

Hart, D.R.T, Yeo, S, Almaraz, M, Beillouin, D, Cardinael, R, Garcia, E, Kay, S, Lovell, S.T., Rosenstock, T.S., Sprenkle-Hyppolite, S, Stolle, F, Suber, M, Thapa, B, Wood, S & Cook-Patton, S.C (2023). “Priority science can accelerate agroforestry as a natural climate solution”. Nature Climate Change. Link to source: https://doi.org/10.5281/zenodo.8209212

Husak, A. L., & Grado, S. C. (2002). Monetary benefits in a southern silvopastoral system. Southern Journal of Applied Forestry, 26(3), 159–164. Link to source: https://doi.org/10.1093/sjaf/26.3.159

IPCC (2019). 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.)]. Link to source: https://www.ipcc.ch/srccl/

IPCC AR6 WG3 (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. Link to source: https://doi.org/10.1017/9781009157926

Jacobsen (2019). Secondary metabolites in leaf hay as a mitigation option for enteric methane production in ruminants. Aarhus University. Link to source: https://pure.au.dk/ws/portalfiles/portal/197235590/Secondary_Metabolites_in_Leaf_Hay_as_a_Mitigation_Option_for_Enteric_Methane_Production_in_Ruminants.pdf

Jose, S., & Dollinger, J. (2019). Silvopasture: a sustainable livestock production system. Agroforestry systems, 93, 1-9. Link to source: https://doi.org/10.1007/s10457-019-00366-8

Lal, R., Smith, P., Jungkunst, H. F., Mitsch, W. J., Lehmann, J., Nair, P. R., & 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

Lee, S., Bonatti, M, Löhe, K, Palacios, V., Lana, M.A., and Sieber, S (2020). Adoption potentials and barriers of silvopastoral systems in Colombia: Case of Cundinamarca region. Cogent Environmental Science 6(1). Link to source: https://doi.org/10.1080/23311843.2020.1823632

Lemes, A. P., Garcia, A. R., Pezzopane, J. R. M., Brandão, F. Z., Watanabe, Y. F., Cooke, R. F., Sponchiado, M., Paz, C. C. P., Camplesi, A. C., Binelli, M., & Gimenes, L. U. (2021). Silvopastoral system is an alternative to improve animal welfare and productive performance in meat production systems. Scientific Reports, 11(1), 14092. Link to source: https://doi.org/10.1038/s41598-021-93609-7

Lorenz, K., & Lal, R. (2018). Carbon sequestration in agricultural ecosystems. Springer, Cham. Link to source: https://link.springer.com/book/10.1007/978-3-319-92318-5

Mehrabi, Z., Tong, K., Fortin, J., Stanimirova, R., Friedl, M., & Ramankutty, N. (2024). Global agricultural lands in the year 2015. Earth System Science Data Discussions, 2024, 1–44. Link to source: https://doi.org/10.5194/essd-2024-279

Montagnini, F (2019). Función de los sistemas agroforestales en la adaptación y mitigación del cambio climático. Sistemas agroforestales: Funciones productivas, socioeconómicas y ambientales, 269-299. Link to source: https://cipav.org.co/wp-content/uploads/2020/08/sistemas-agroforestales-funciones-productivas-socioeconomicas-y-ambientales.pdf

Morena, G., & Rolo, V. (2019). Agroforestry practices: Silvopastoralism. In Agroforestry for sustainable agricultura (1st ed.). Burleigh Dodds Science Publishing. Link to source: https://doi.org/10.1201/9780429275500

Murgueitio, E., Uribe, F., Molina, C., Molina, E., Galindo, W., Chará, J., & González, J. (2016). Establecimiento y manejo de sistemas silvopastoriles intensivos con Leucaena. Editorial CIPAV, Cali, Colombia. Link to source: https://www.researchgate.net/profile/Juan-Naranjo-R/publication/310460876_Establecimiento_y_manejo_de_sistemas_silvopastoriles_intensivos_con_leucaena/links/582e30cb08ae138f1c01d8b9/Establecimiento-y-manejo-de-sistemas-silvopastoriles-intensivos-con-leucaena.pdf

Nair, P.K. R. (2012). Climate change mitigation: A low-hanging fruit of agroforestry. Agroforestry: The future of global land use, 31–69. Link to source: https://doi.org/10.1007/978-94-007-4676-3_7

Ortiz, J., Neira, P., Panichini, M., Curaqueo, G., Stolpe, N. B., Zagal, E., & Gupta, S. R. (2023). Silvopastoral systems on degraded lands for soil carbon sequestration and climate change mitigation. Agroforestry for Sustainable Intensification of Agriculture in Asia and Africa, 207–242. Link to source: https://doi.org/10.1007/978-981-19-4602-8_7

Pent, G. J. (2020). Over-yielding in temperate silvopastures: a meta-analysis. Agroforestry Systems, 94(5), 1741–1758. Link to source: https://doi.org/10.1007/s10457-020-00494-6

Pezo, D., Ríos, N., Ibrahim, M., & Gómez, M. (2018). Silvopastoral systems for intensifying cattle production and enhancing forest cover: the case of Costa Rica. Washington, DC: World Bank. Link to source: https://www.profor.info/sites/default/files/Silvopastoral%2520systems_Case%2520Study_LEAVES_2018.pdf

Poudel, S., Pent, G., & Fike, J. (2024). Silvopastures: Benefits, past efforts, challenges, and future prospects in the United States. Agronomy, 14(7), 1369. Link to source: https://doi.org/10.3390/agronomy14071369

Quandt, A, Neufeldt, G, & Gorman, K (2023). Climate change adaptation through agroforestry: Opportunities and gaps. Current Opinion in Environmental Sustainability. 60, 101244. Link to source: https://doi.org/10.1016/j.cosust.2022.101244

Rivera, J. E., Serna, L., Arango, J., Barahona, R., Murgueitio, E., Torres, C. F., & Chará, J. (2023). Silvopastoral systems and their role in climate change mitigation and Nationally Determined Contributions in Latin America. In Silvopastoral systems of Meso America and Northern South America (pp. 25–53). Cham: Springer International Publishing. Link to source: https://doi.org/10.1007/978-3-031-43063-3_2

Rojas, D, & Rodriguez Anido, N. (2022) Potential of silvopastoral systems for the mitigation of greenhouse gasses generated in the production of bovine meat. In Sistemas silvopastoriles: Hacia una diversificación sostenible. CIPAV. Link to source: https://cipav.org.co/sistemas-silvopastoriles-hacia-una-diversificacion-sostenible/

Riset, J.Å., Tømmervik, H. & Forbes, B.C. (2019). Sustainable and resilient reindeer herding. Reindeer Caribou Health Dis, (23–43). Link to source: https://www.researchgate.net/publication/344787755_Ch13_Sustainable_and_resilient_reindeer_herding

Shelton, M., Dalzell, S., Tomkins, N. and Buck, S. R. (2021). Leucaena: The productive and sustainable forage legume. University of Queensland. Link to source: https://era.dpi.qld.gov.au/id/eprint/9425/

Shi, L., Feng, W., Xu, J., & Kuzyakov, Y. (2018). Agroforestry systems: Meta‐analysis of soil carbon stocks, sequestration processes, and future potentials. Land Degradation & Development, 29(11), 3886–3897. Link to source: https://doi.org/10.1002/ldr.3136

Smith, M. M., Bentrup, G., Kellerman, T., MacFarland, K., Straight, R., Ameyaw, L., & Stein, S. (2022). Silvopasture in the USA: A systematic review of natural resource professional and producer-reported benefits, challenges, and management activities. Agriculture, Ecosystems & Environment, 326, 107818. Link to source: https://doi.org/10.1016/j.agee.2021.107818

Sprenkle-Hyppolite, S. Griscom, B., Griffey, V., Munshi, E., Chapman, M. (2024). Maximizing tree carbon in cropland and grazing lands while sustaining yields. Carbon Balance and Management 19:23. Link to source: https://doi.org/10.1186/s13021-024-00268-y

Toensmeier, E. (2017). Perennial staple crops and agroforestry for climate change mitigation. Integrating landscapes: Agroforestry for biodiversity conservation and food sovereignty, 439-451. Link to source: https://doi.org/10.1007/978-3-319-69371-2_18

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Udawatta, R. P., Walter, D., & Jose, S. (2022). Carbon sequestration by forests and agroforests: A reality check for the United States. Carbon footprints, 1(8). Link to source: https://doi.org/10.20517/cf.2022.06 

Zeppetello, L. R. V., Cook-Patton, S. C., Parsons, L. A., Wolff, N. H., Kroeger, T., Battisti, D. S., Bettles, J., Spector, J. T., Balakumar, A., & Masuda, Y. J. (2022). Consistent cooling benefits of silvopasture in the tropics. Nature communications, 13(1), 708. Link to source: https://doi.org/10.1038/s41467-022-28388-4

Zhu, X., Liu, W., Chen, J., Bruijnzeel, L. A., Mao, Z., Yang, X., Cardinael, R., Meng, F.-R., Sidle, R. C., Seitz, S., Nair, V. D., Nanko, K., Zou, X., Chen, C., & Jiang, X. J. (2020). Reductions in water, soil and nutrient losses and pesticide pollution in agroforestry practices: A review of evidence and processes. Plant and Soil, 453(1–2), 45–86. Link to source: https://doi.org/10.1007/s11104-019-04377-3

Credits

Lead Fellow

  • Eric Toensmeier

Contributors

  • Ruthie Burrows, Ph.D.

  • Yusuf Jameel, Ph.D.

  • Daniel Jasper

Internal Reviewers

  • Aiyana Bodi

  • Hannah Henkin

  • Ted Otte

  • Paul C. West, Ph.D.

Effectiveness

We found a median carbon sequestration rate of 9.81 t CO₂‑eq /ha/yr (Table 1). This is based on an above-ground biomass (tree trunks and branches) accumulation rate of 6.43 t CO₂‑eq /ha/yr and a below-ground biomass (roots) accumulation rate of 1.61 t CO₂‑eq /ha/yr using a root-to-shoot ratio of 0.25 (Cardinael et al., 2019). These are added to the soil organic carbon sequestration rate of 1.76 t CO₂‑eq /ha/yr to create the combined total.

Table 1. Effectiveness at carbon sequestration.

Unit: t CO₂-eq/ha/yr, 100-yr basis

25th percentile 4.91
Mean 14.70
Median (50th percentile) 9.81
75th percentile 20.45

100-yr basis

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Reductions in nitrous oxide and methane and sustainable intensification impacts are not yet quantifiable to the degree that they can be used in climate mitigation projections.

Cost

Because baseline grazing systems are already extensive and well established, we assumed there is no cost to establish new baseline grazing land. In the absence of global data sets on costs and revenues of grazing systems, we used a global average profit per hectare of grazing land of US$6.28 from Damania et al. (2023).

Establishment costs of silvopasture vary widely. We found the cost to establish one hectare of silvopasture to be US$1.06–4,825 (Dupraz & Liagre, 2011; Lee et al., 2011). Reasons for this wide range include the low cost of natural regeneration and the broad range in tree density depending on the type of system. We collected costs by region and used a weighted average to obtain a global net net cost value of US$424.20.

Cost and revenue data for silvopasture were insufficient. However, data on the impact on revenues per hectare are abundant. Our analysis found a median 8.7% increase in per-hectare profits from silvopasture compared with conventional grazing, which we applied to the average grazing value to obtain a net profit of US$6.82/ha. This does not reflect the very high revenues of silvopasture systems in some countries.

We calculated cost per t CO₂‑eq sequestered by dividing net net cost/ha by total CO₂‑eq sequestered/ha.

Table 2. Cost per unit of climate impact.

Unit: 2023 US$/t CO₂-eq

Median $43.25

100-yr basis & 20-yr basis are the same.

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Methods and Supporting Data

Methods and Supporting Data

Learning Curve

There is not enough information available to determine a learning curve for silvopasture. However, anecdotal evidence showed establishment costs decreasing as techniques for broadscale mechanized establishment were developed in Australia and Colombia (Murguietio et al., 2016; Shelton et al., 2021).

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.

Deploy Silvopasture 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.

Caveats

Permanence

Living biomass and soil organic matter only temporarily hold carbon (decades to centuries for soil organic matter, and for the life of the tree or any long-lived products made from its wood in the case of woody biomass). Sequestered carbon in both soils and biomass is vulnerable to fire, drought, long-term shifts to a drier precipitation regime, and other climate change impacts, as well as to a return to the previous farming or grazing practices. Such disturbances can cause carbon to be re-emitted to the atmosphere (Lorenz & Lal, 2018). 

Saturation

Like all upland, terrestrial agricultural systems, over the course of decades, silvopastures reach saturation and net sequestration slows to nearly nothing (Lorenz & Lal, 2018). 

Current Adoption

Lack of data on the current adoption of silvopasture is a major gap in our understanding of the potential of this solution. One satellite imaging study found 156 million ha of grazing land with more than 10 t C/ha in above-ground biomass, which is the amount that indicates more than grass alone (Chapman et al., 2019). However, this area includes natural savannas, which are not necessarily silvopastures, and undercounts the existing 15.1 million ha of silvopasture known to be present in Europe (den Herder et al., 2017).

Sprenkle-Hippolite et al. (2024) estimated a current adoption of 141.4 Mha, or 6.0% of grazing land (Table 3). We have chosen this more recent figure as the best available estimate of current adoption. Note that in Solution Basics in the dashboard above 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).

Table 3. Current (2023) adoption level.

Unit: million ha

Mean 141.4
Left Text Column Width
Adoption Trend

There is little quantifiable information reported about silvopasture adoption trends.

Adoption Ceiling

Grazing is the world’s largest land use at 2,986 Mha (Mehrabi et al., 2024). Much grazing land is too dry for trees, while other grasslands that were not historically forest or savanna should not be planted with trees in order to minimize water use and protect grassland habitat (Dudley et al., 2020). Three studies estimated the total potential area suitable for silvopasture (including current adoption). 

Lal et al. (2018) estimated the technical potential for silvopasture adoption at 550 Mha.

Chapman et al. (2019) estimated the suitable area for increased woody biomass on grazing land as 1,890 Mha. 

Sprenkle-Hippolite (2024) assessed the maximum area of grazing land to which trees could be added without reducing livestock productivity. They calculated a total of 1,589 Mha, or 67% of global grazing land (Table 4). To our knowledge, this is the most accurate estimate available. 

Table 4. Adoption ceiling.

Unit: ha converted

25th percentile 1069000000
Mean 1343000000
Median (50th percentile) 1588000000
75th percentile 1739000000

Unit: % of grazing land

25th percentile 45
Mean 36
Median (50th percentile) 53
75th percentile 58
Left Text Column Width
Achievable Adoption

In our Achievable – High scenario, global silvopasture starts at 141.4 Mha and grows at the Colombian Nationally Determined Contribution growth rate of 6.5%/yr. This would provide the high end of the achievable potential at 206.3 Mha by 2030, of which 64.9 million ha are newly adopted (Table 5). For the Achievable – Low scenario, we chose 1/10 of Colombia’s projected growth rate. This would provide 147.0 Mha of adoption by 2030, of which 5.6 Mha are new.

Few estimates of the global adoption potential of silvopasture are available, and even those for the broader category of agroforestry are rare due to the lack of solid data on current adoption and growth rates (Shi et al., 2018; Hart et al., 2023). The IPCC estimates that, for agroforestry overall, 19.5% of the technical potential is economically achievable (IPCC AR6 WG3, 2022). Applying this rate to Sprenkle-Hippolite’s estimated 1,588 Mha technical potential yields an achievable potential of 310 Mha of convertible grazing land.

Our high adoption rate reaches 13% of the adoption ceiling by 2030. This suggests that silvopasture represents a large but relatively untapped potential that will require aggressive policy action and other incentives to spur scaling.

Table 5. Range of achievable adoption levels.

Unit: Mha

Current adoption 141.4
Achievable – low 147.0
Achievable – high 206.3
Adoption ceiling 1,588.0

Unit: Mha

Current adoption 0.00
Achievable – low 5.6
Achievable – high 64.9
Adoption ceiling 1,447.4
Left Text Column Width

Carbon sequestration continues only for a period of decades; because silvopasture is an ancient practice with some plantings centuries old, we could not assume that previously adopted hectares continue to sequester carbon indefinitely. Much of the current adoption of silvopasture has been in place for centuries and sequestration there has presumably already slowed down to almost zero. We apply an adoption adjustment factor of 0.25 to current adoption (see Methodology) to reflect that most current adoption is no longer sequestering significant carbon, yet there is substantial new adoption within the past 20–50 years.

For new adoption the calculation is effectiveness * new adoption = climate impact.

For current adoption the calculation is effectiveness * 0.25 * current adoption = climate impact

Climate impacts shown in Table 6 are the sum of current and new adoption impacts. Carbon sequestration impact is 0.35 Gt CO₂‑eq/yr for current adoption, 0.40 Gt CO₂‑eq/yr for Achievable – Low, 0.98 Gt CO₂‑eq/yr for Achievable – High, and 14.54 Gt CO₂‑eq/yr for our Adoption Ceiling. 

Table 6. Climate impact at different levels of adoption.

Unit: Gt CO₂‑eq/yr

Current adoption 0.35
Achievable – low 0.40
Achievable – high 0.98
Adoption ceiling 14.54

100-yr basis, New adoption only 

Left Text Column Width

Lal et al. (2018) estimated a technical global carbon sequestration potential of 0.3–1.0 Gt CO₂‑eq/yr. Sprenkle-Hyppolite et al. (2024) estimated a silvopasture technical potential of 1.4 Gt CO₂‑eq/yr ; this assumes a tree density of 2–6 trees/ha, which is substantially lower than typical silvopasture. For agroforestry overall (including silvopasture and other practices), the IPCC (2022) estimates an achievable potential of 0.8 Gt CO₂‑eq/yr and a technical potential of 4.0 Gt CO₂‑eq/yr.

Additional Benefits

Income and Work 

Silvopasture can also increase and diversify farmer income. Tree fruit and timber often provide income for ranchers. A study in the southern United States showed that silvopasture systems generated 10% more income than standalone cattle production (Husak & Grado, 2002). A more comprehensive analysis across the eastern United States (Greene et al., 2023) found that virtually all silvopasture systems assessed had a positive 20- and 30-yr internal rate of return (IRR). For some systems, the 30-yr IRR can be >15% (Greene et al., 2023).

Food Security

While evidence on the impact of silvopasture on yields is mixed, this practice can improve food security by diversifying food production and income sources (Bostedt et al., 2016; Smith et al., 2022). In pastoralists in Kenya, Bostedt et al. (2016) found that agroforestry practices were associated with increased dietary diversity, an important aspect of food and nutrition security. Diverse income streams can mediate household food security during adverse conditions, such as droughts or floods, especially in low- and middle-income countries (de Sherbinin et al., 2008; Di Prima et al., 2022; Frelat et al., 2016). 

Nature Protection

Trees boost habitat availability, enhance landscape connectivity, and aid in forest regeneration and restoration. In most climates they provide a major boost to biodiversity compared with pasture alone (Smith et al., 2022; Pezo et al., 2018). 

Animal Well-being

By providing shade, silvopasture systems reduce heat stress experienced by livestock. Heat stress for cattle begins at 30 °C or even lower in some circumstances (Garrett et al., 2004). In the tropics, the cooling effect of integrating trees into a pastoral system is 0.32–2.4 °C/t of woody carbon added/ha (Zeppetello et al., 2022). Heifers raised in silvopasture systems had higher body mass and more optimal body temperature than those raised in intensive rotational grazing systems (Lemes et al., 2021). Improvement in livestock physiological conditions probably results from access to additional forage, increased livestock comfort, and reduced heat stress in silvopastoral systems. Silvopasture is highly desirable for its improvements to animal welfare (Goracci & Camilli, 2024).

Land Resources

Silvopasture and agroforestry are important for ensuring soil health (Basche et al., 2020). These practices improve soil health by reducing erosion and may also contribute to soil organic matter retention (U.S. Department of Agriculture Natural Resource Conservation Service ([USDA NRCS], 2025). There is evidence that silvopasture may improve soil biodiversity by preventing soil organism habitat loss and degradation (USDA NRCS, 2025).

Water Quality

Perennials in silvopasture systems could reduce runoff and increase water infiltration rates relative to open rangelands (Smith et al., 2022; Pezo et al., 2018). This increases the resilience of the system during drought and high heat. Silvopasture can improve water quality by retaining soil sediments and filtering pollutants found in runoff (USDA NRCS, 2025). On average, silvopasture and agroforestry practices can reduce runoff of sediments and excess nutrients into water 42–47% (Zhu et al., 2020). The filtering benefits of silvopasture can also mitigate pollution of antibiotics from livestock operations from entering waterways (Moreno & Rolo, 2019). 

Risks

Some of the tree and forage species used in silvopastures are invasive in certain contexts. For example, river tamarind (Leucaena leucocephala) is a centerpiece in intensive silvopasture in Latin America, where it is native, but also in Australia, where it is not. Australian producers have developed practices to limit or prevent its spread (Shelton et al., 2021).

Livestock can damage or kill young trees during establishment. Protecting trees or excluding grazing animals during this period increases costs (Smith et al., 2022).

Poorly designed tree layout can make herding, haying, fencing, and other management activities more difficult. Tree densities that are too high can reduce livestock productivity (Cadavid et al., 2020).

Interactions with Other Solutions

Reinforcing

Silvopasture represents a way to produce some ruminant meat and dairy in a more climate-friendly way. This impact can contribute to addressing emissions from ruminant production, but only as part of a program that strongly emphasizes diet change and food waste reduction.

Forms of silvopasture that increase milk and meat yields can reduce pressure to convert undeveloped land to agriculture.

Silvopasture is a technique for restoring farmland.

Silvopasture is a form of savanna restoration.

Competing

Expanding silvopasture could restrict land availability for renewable energy or raw material and food production, since many technologies and practices could be sited on grazing lands. Silvopasture and forest restoration can also compete for the same land.

Silvopasture is a kind of agroforestry, though in this iteration of Project Drawdown “Deploy Agroforestry” refers to crop production systems only. With that said, some agroforestry systems integrate both crops and livestock with the trees, such as the widespread parkland systems of the African Sahel.

Dashboard

Solution Basics

ha converted from grazing land to silvopasture

t CO₂-eq (100-yr)/unit/yr
04.919.81median
units
Current 1.414×10⁸ 01.47×10⁸2.063×10⁸
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.35 0.40.98
US$ per t CO₂-eq
43
Delayed

CO₂

Trade-offs

Solutions that improve ruminant production could undermine the argument for reducing ruminant protein consumption in wealthy countries. 

Certain silvopasture systems reduce per-hectare productivity of meat and milk, even if overall productivity increases when the yields of timber or food from the tree component are included. For example, silvopasture systems that are primarily focused on timber production, with high tree densities, will have lower livestock yields than pasture alone - though they will have high timber yields.

The costs of establishment are much higher than those of managed grazing. There is also a longer payback period (Smith et al., 2022). These limitations mean that secure land tenure is even more important than usual, to make adoption worthwhile (Poudel et al., 2024).

Maps Introduction

Silvopasture is primarily appropriate for grazing land that receives sufficient rainfall to support tree growth. While it can be implemented on both cropland and grassland, if adopted on cropland, it will reduce food yield because livestock produce much less food per hectare than crops. In the humid tropics, a particularly productive and high-carbon variation called intensive silvopasture is an option. Ideally, graziers will have secure land tenure, though pastoralist commons have been used successfully.

Areas too dry to establish trees (<450 mm annual precipitation) are not suitable for silvopasture by tree planting, but regions that can support natural savanna may be suitable for managed natural regeneration.

Most silvopasture today appears in sub-Saharan Africa (Chapman et al., 2019), though this may reflect grazed natural savannas rather than intentional silvopasture. This finding neglects well-known systems in Latin America and Southern Europe. 

Chapman et al. (2019) listed world grasslands by their potential to add woody biomass. According to their analysis, the countries with the greatest potential to increase woody biomass carbon in grazing land are, in order: Australia, Kazakhstan, China, the United States, Mongolia, Iran, Argentina, South Africa, Sudan, Afghanistan, Russia, and Mexico. Tropical grazing land accounts for 73% of the potential in one study. Brazil, China, and Australia have the highest areas, collectively accounting for 37% of the potential area (Sprenkle-Hippolite 2024).

We do not present any maps for the silvopasture solution due to the uncertainties in identifying current areas where silvopasture is practiced, and in identifying current grasslands that were historically forest or savanna. 

Action Word
Deploy
Solution Title
Silvopasture
Classification
Highly Recommended
Lawmakers and Policymakers
  • Lower the risk for farmers transitioning from other pastoral systems.
  • Increase understanding of silvopasture.
  • Reduce technical and bureaucratic complexity.
  • Establish or expand technical assistance programs.
  • Simplify incentive programs.
  • Ensure an appropriate and adequate selection of tree species are eligible for incentives.
  • Establish a silvopasture certification program.
  • Create demonstration farms.
  • Strengthen land tenure laws.
  • Incentivize lease structures to facilitate silvopasture transitions on rented land.

Further information:

Practitioners
  • Seek support from technical assistance programs and extension services.
  • Seek out networks of adopters to share information, resources, best practices, and collective marketing.
  • If available, leverage incentive programs such as subsidies, tax rebates, grants, and carbon credits.
  • Negotiate new lease agreements to accommodate silvopasture techniques or advocate for public incentives to reform lease structures.

Further information:

Business Leaders
  • Prioritize suppliers and source from farmers who use silvopasture.
  • Provide innovative financial mechanisms to encourage adoption.
  • Participate in and help create high-quality carbon credit programs.
  • Incentivize silvopasture transitions in lease agreements.
  • Support the creation of a certification system to increase the marketability of silvopasture products.
  • Join coalitions with other purchasers to grow demand.
  • Collaborate with public and private agricultural organizations on education and training programs. 

Further information:

Nonprofit Leaders
  • Educate farmers and those who work in the food industry about the benefits of silvopasture.
  • Communicate any government incentives for farmers to transition to silvopasture.
  • Explain how to take advantage of incentives.
  • Provide training material and/or work with extension services to support farmers transitioning to silvopasture, such as administering certification programs.
  • Advocate to policymakers for improved incentives for farmers, stronger land tenure laws, and flexible lease agreements.

Further information:

Investors
  • Use capital like low-interest or favorable loans to support farmers and farmer cooperatives exploring silvopasture projects.
  • Invest in credible, high-quality carbon reduction silvopasture projects.
  • Invest in silvopasture products (e.g., fruits, berries, and other tree products)
  • Encourage favorable lease agreements between landowners or offer favorable costs and benefit-sharing structures.
  • Consider banking through community development financial institutions or other institutions that support farmers. 

Further information:

Philanthropists and International Aid Agencies
  • Provide grants and loans for establishing silvopasture and support farmland restoration projects that include silvopasture.
  • Support capacity-building, market access, education, and training opportunities for smallholder farmers – especially those historically underserved – through activities like farmer cooperatives, demonstration farms, and communal tree nurseries.
  • Consider banking through Community Development Financial Institutions or other institutions that support farmers. 

Further information:

Thought Leaders
  • Use your platform to build awareness of silvopasture and its benefits, incentive programs, and regulatory standards.
  • Provide technical information to practitioners.
  • Host community dialogues such as Edible Connections to engage the public about silvopasture and other climate-friendly farming practices.

Further information:

Technologists and Researchers
  • Improve the affordability and equipment needed to plant and manage trees.
  • Refine satellite tools to improve silvopasture detection.
  • Develop ways to monitor changes in soil and biomass.
  • Standardize data collection protocols.
  • Create a framework for transparent reporting and reliable verification.
  • Fill gaps in data, such as quantifying the global adoption potential of silvopasture and regional analysis of revenue and operating costs/hectare. 

Further information:

Communities, Households, and Individuals
  • Purchase silvopasture products and support farmers who use the practice.
  • Request silvopasture products at local markets.
  • Encourage policymakers to help farmers transition.
  • Encourage livestock farmers to adopt the practice.
  • Host community dialogues such as Edible Connections to engage the public about silvopasture and other climate-friendly farming practices.

Further information:

Sources
Evidence Base

Consensus of effectiveness in sequestering carbon: Mixed to High 

There is a high level of consensus about the carbon biosequestration impacts of silvopasture, including for the higher per-hectare sequestration rates relative to improved grazing systems alone. A handful of reviews, expert estimations, and meta-analyses have been published on the subject. These include:

Cardinael et al. (2018) assembled data by climate and region for use in the national calculations and reporting. 

Chatterjee et al. (2018) found that converting from pasture to silvopasture increases carbon stocks. 

Lal et al. ( 2018) estimated the technical adoption and mitigation potential of silvopasture and other practices.

Udawatta et al. (2022) provided an up-to-date meta-analysis for temperate North America. 

The results presented in this document summarize findings from two reviews, two meta-analyses, one expert opinion and three original studies reflecting current evidence from a global scale. We recognize this limited geographic scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

Consensus regarding other climate impacts: Low

There is low consensus on the reduction of methane from enteric emissions, nitrous oxide from manure, and CO₂ from avoided deforestation due to increased productivity. We do not include these climate impacts in our calculations.

Consensus regarding adoption potential: Low

Until recently there was little understanding of the current adoption of silvopasture. Sprenkle-Hyppolite et al. (2024) used Delphi expert estimation to determine current adoption and technical potential. Rates of adoption and achievable potential are still largely unreported or uninvestigated. See the Adoption section for details.

Updated Date

Deploy Agroforestry

Submitted by Drawdown Admin on
Sector
Nature-Based Carbon Removal
Mode
Remove Carbon
Cluster
Shift Agriculture Practices
Image
Peatland
Coming Soon
On
Description for Social and Search
The Deploy Agroforestry solution is coming soon.
Methods and Supporting Data

Methods and Supporting Data

Dashboard
Action Word
Deploy
Solution Title
Agroforestry
Classification
Highly Recommended
Updated Date

Protect Seaweed Ecosystems

Submitted by Drawdown Admin on
Sector
FALO & Nature-Based Carbon Removal
Mode
Cut Emissions and Remove Carbon
Cluster
Protect & Manage Ecosystems
Image
Seaweed
Coming Soon
Off
Summary

Seaweed ecosystem protection is the long-term protection from degradation of wild subtidal brown and red seaweed ecosystems. Seaweeds, also called macroalgae, are photosynthetic marine organisms that absorb CO₂ from the water and convert it into biomass. This can lower surface-water CO₂ concentrations, allowing additional CO₂ from the atmosphere to be dissolved in the ocean. Some of the fixed carbon can be sequestered through export to the deep sea or burial in the seafloor, while a portion may persist in forms that resist degradation even at the ocean surface. 

Protecting seaweed ecosystems can reduce a range of human impacts (wild harvesting, coastal development, overgrazing, and poor water quality) and improve resilience to other stressors (warming), which helps preserve carbon removal by the seaweed and avoid CO₂ emissions from biomass losses. 

This solution focuses on legal mechanisms of protection through the establishment of Marine Protected Areas (MPAs), which are managed with the primary goal of conserving nature. This solution does not include cultivated seaweed (see Deploy Seaweed Farming for Food).

Extreme weather events
Income & work,Food security,Equality
Nature protection,Water quality
Description for Social and Search
Protecting seaweed ecosystems is a Highly Recommended climate solution. It can likely deliver globally relevant levels of climate impact while providing additional benefits for humans and ecosystems.
Overview

Seaweeds are diverse marine photosynthetic organisms composed of three groups: brown (Phaeophyceae), green (Chlorophyta), and red algae (Rhodophyta). They can form ecosystems, such as kelp forests, and contribute to other marine ecosystems by providing habitat and food. Seaweeds are distinguished from other algae, such as phytoplankton, based on their larger size and because most are attached to substrate rather than free-floating. Seaweeds cover an estimated 600 Mha of the ocean (Duarte et al., 2022), an area that is an order of magnitude greater than the area associated with coastal wetlands (~55 Mha, see Protect Coastal Wetlands). 

This solution focuses on wild subtidal (always submerged) brown and red seaweed ecosystems, which together account for over 75% of global seaweed extent (Duarte et al., 2022) (Figure 1). We do not include green seaweeds due to their smaller extent and data limitations. We also do not include seaweeds that occur in intertidal zones, as free-floating colonies (e.g., some species of Sargassum) or are cultivated due to data limitations or coverage in other Explorer solutions (e.g., Deploy Seaweed Farming for Food).

Figure 1. Seaweed ecosystem types considered in this solution (left to right): subtidal brown (central California, USA) and subtidal red (Atlantic coast of Spain)

Two photos demonstrating seaweed ecosystem types. Left: subtidal brown. Right: subtidal red.

fdastudillo | iStock; Damocean | iStock

Seaweed ecosystems exhibit high net primary productivity (NPP) rates, comparable to those of terrestrial forests (Filbee-Dexter, 2020). Unlike many terrestrial ecosystems, however, nearly all carbon storage in seaweed ecosystems occurs as above-ground biomass, since seaweeds lack below-ground roots. A smaller amount can be buried on site in sediment (Krause-Jensen & Duarte, 2016). Most long-term carbon storage attributable to seaweeds occurs largely outside of seaweed ecosystems, through the export of carbon in dissolved and suspended forms (Figure 2). Some of this carbon reaches the deep sea, where it can persist for more than 100 years (Krause-Jensen & Duarte, 2016; Krause-Jensen et al., 2018; Ortega et al., 2019). Roughly 11.4% (25th quartile, 6.0%; 75th quartile, 13.7%) of NPP from global seaweed ecosystems is estimated to contribute to long-term carbon storage in the deep sea, equivalent to as much as 0.62 Gt CO₂‑eq/yr (173 Tg C/yr, Krause-Jensen & Duarte, 2016). While uncertain and requiring more research, recent modeling efforts support these estimates, suggesting that more than 12.5% of NPP may be removed on 100-yr timescales (Filbee-Dexter et al., 2024b).

Figure 2. Overview of a seaweed ecosystem showing carbon fluxes into and out of the ecosystem (g=gaseous, aq=aqueous) that can result in carbon removal. Some carbon is exported to the shallow sea, where it may be recycled or persist for longer periods depending on its form, some is exported to the deep sea (~1000 m), and some is buried in seafloor sediments. 

diagram illustration of seaweed ecosystem, showing carbon fluxes into and out of the ecosystem

Adapted from: Hurd, C. L., Gattuso, J.-P., & Boyd, P. W. (2024). Air-sea carbon dioxide equilibrium: Will it be possible to use seaweeds for carbon removal offsets? Journal of Phycology, 60(1), 4–14. 

Seaweed ecosystems face growing threats from a range of climate change impacts (Harley et al., 2012), such as increasing sea surface temperatures, marine heat waves, ocean acidification, and extreme storm events, as well as local drivers, such as overfishing, overgrazing, pollution, disease outbreaks, invasive species, and bottom fishing (Corrigan et al., 2025; Filbee-Dexter et al., 2024a; Hanley et al., 2024). For instance, overfishing can deplete top predators in ecosystems, leading to increases in herbivores, such as sea urchins, that overgraze seaweed (Steneck et al., 2002). 

In this solution, we calculate how legal protection of seaweed ecosystems via MPAs can reduce CO₂ emissions and preserve carbon removal through avoided ecosystem loss. In addition to preventing direct losses from impacts such as wild harvest, MPAs can help restore predator populations that keep herbivores in balance. For instance, many MPAs include no-take zones that allow predatory fish populations to recover, thereby lessening overgrazing impacts over time. MPAs can also increase the resilience of seaweed ecosystems against climate change stressors, such as marine heat waves (Kumagai et al., 2024; Ortiz-Villa et al., 2025). While some seaweed can release methane, offsetting CO₂ removal (Roth et al., 2023), we exclude this process from our analysis due to existing data limitations. We also do not consider nitrous oxide, though protection might provide additional climate benefits because enhanced nitrous oxide production has been tied to nutrient-polluted seaweed systems (Wong et al., 2021). 

We present estimates of climate impact as likely upper bounds under several key assumptions (see Appendix and Caveats), which can be improved upon as more research unfolds. We consider subtidal brown and red seaweed to be protected if they are within designated MPAs based on global datasets from UNEP-WCMC and IUCN (2024). Importantly, protection can help reduce – but will not eliminate – ecosystem loss in MPAs relative to unprotected areas (see Effectiveness). 

Akaike, S., & Mizuta, H. (2024). Optimizing the biomass balance of macroalgae and sea urchins in kelp beds by removing the urchins. European Journal of Phycology, 59(2), 218–231. Link to source: https://doi.org/10.1080/09670262.2024.2306397

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

Bauer, J., Beas-Luna, R., Malpica-Cruz, L., Abadía-Cardoso, A., Filz, P., Bonilla, J. C., & Lorda, J. (2025). Community-led management maintains higher predator biomass supporting kelp forests persistence in Baja California. Scientific Reports, 15(1), Article 23253. Link to source: https://doi.org/10.1038/s41598-025-86140-6

Best, R. J., Chaudoin, A. L., Bracken, M. E. S., Graham, M. H., & Stachowicz, J. J. (2014). Plant–animal diversity relationships in a rocky intertidal system depend on invertebrate body size and algal cover. Ecology, 95(5), 1308–1322. Link to source: https://doi.org/10.1890/13-1480.1

Corrigan, S., Cottier-Cook, E. J., Lim, P. E., & Brodie, J. (2025). The state of the world’s seaweeds 2025 [Data set]. Natural History Museum. Link to source: https://doi.org/10.5519/4ln9oqk7

Cotas, J., Gomes, L., Pacheco, D., & Pereira, L. (2023). Ecosystem services provided by seaweeds. Hydrobiology, 2(1), 75–96. Link to source: https://doi.org/10.3390/hydrobiology2010006

Cottier-Cook, E. J., Lim, P. E., Mallinson, S., Yahya, N., Poong, S. W., Wilbraham, J., Nagabhatla, N., & Brodie, J. (2023). Striking a balance: Wild stock protection and the future of our seaweed industries [Policy brief]. United Nations University Institute on Comparative Regional Integration Studies. Link to source: https://cris.unu.edu/sites/cris.unu.edu/files/UNU-CRIS_Policy-Brief_CottierCook_Et.al_23.06.pdf

Cuba, D., Guardia-Luzon, K., Cevallos, B., Ramos-Larico, S., Neira, E., Pons, A., & Avila-Peltroche, J. (2022). Ecosystem services provided by kelp forests of the Humboldt current system: A comprehensive review. Coasts, 2(4), 259–277. Link to source: https://doi.org/10.3390/coasts2040013

Duarte, C. M., Gattuso, J. P., Hancke, K., Gundersen, H., Filbee-Dexter, K., Pedersen, M. F., Middelburg, J. J., Burrows, M. T., Krumhansl, K. A., Wernberg, T., Moore P., Pessarrodona, A., Ørberg, S. B., Pinto, I. S., Assis, J., Queirós, A. M., Smale, D. A., Bekkby, T., Serrão, E. A., & Krause-Jensen, D. (2022). Global estimates of the extent and production of macroalgal forests. Global Ecology and Biogeography, 31(7), 1422–1439. Link to source: https://doi.org/10.1111/geb.13515

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Eger, A. M., Eddy, N., McHugh, T. A., Arafeh-Dalmau, N., Wernberg, T., Krumhansl, K., Verbeek, J., Branigan, S., Kuwae, T., Caselle, J. E., Ospina, A. G., & Vergés, A. (2024). State of the world’s kelp forests. One Earth, 7(11), 1927–1931. Link to source: https://doi.org/10.1016/j.oneear.2024.10.008

Eger, A. M., Marzinelli, E. M., Christie, H., Fagerli, C. W., Fujita, D., Gonzalez, A. P., Hong, S. W., Kim, J. H., Lee, L. C., McHugh, T. A., Nishihara, G. N., Tatsumi, M., Steinberg, P. D., & Vergés, A. (2022). Global kelp forest restoration: Past lessons, present status, and future directions. Biological Reviews, 97(4), 1449–1475. Link to source: https://doi.org/10.1111/brv.12850

Eger, A. M., Marzinelli, E. M., Beas-Luna, R., Blain, C. O., Blamey, L. K., Byrnes, J. E. K., Carnell, P. E., Choi, C. G., Hessing-Lewis, M., Kim, K. Y., Kumagai, N. H., Lorda, J., Moore, P., Nakamura, Y., Pérez-Matus, A., Pontier, O., Smale, D., Steinberg, P. D., & Vergés, A. (2023). The value of ecosystem services in global marine kelp forests. Nature Communications, 14(1), Article 1894. Link to source: https://doi.org/10.1038/s41467-023-37385-0

Elsmore, K., Nickols, K. J., Miller, L. P., Ford, T., Denny, M. W., & Gaylord, B. (2024). Wave damping by giant kelp, Macrocystis pyrifera. Annals of Botany, 133(1), 29–40. Link to source: https://doi.org/10.1093/aob/mcad094

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Filbee-Dexter, K., Feehan, C. J., Smale, D. A., Krumhansl, K. A., Augustine, S., de Bettignies, F., Burrows, M. T., Byrnes, J. E. K., Campbell, J., Davoult, D., Dunton, K. H., Franco, J. N., Garrido, I., Grace, S. P., Hancke, K., Johnson, L. E., Konar, B., Moore, P. J., Norderhaug, K. M., … Wernberg, T. (2022). Kelp carbon sink potential decreases with warming due to accelerating decomposition. PLOS Biology, 20(8), Article e3001702. Link to source: https://doi.org/10.1371/journal.pbio.3001702

Filbee‐Dexter, K., Starko, S., Pessarrodona, A., Wood, G., Norderhaug, K. M., Piñeiro‐Corbeira, C., & Wernberg, T. (2024a). Marine protected areas can be useful but are not a silver bullet for kelp conservation. Journal of Phycology, 60(2), 203–213. Link to source: https://doi.org/10.1111/jpy.13446

Filbee-Dexter, K., Pessarrodona, A., Pedersen, M. F., Wernberg, T., Duarte, C. M., Assis, J., Bekkby, T., Burrows, M. T., Carlson, D. F., Gattuso, J.-P., Gundersen, H., Hancke, K., Krumhansl, K. A., Kuwae, T., Middelburg, J. J., Moore, P. J., Queirós, A. M., Smale, D. A., Sousa-Pinto, I., … Krause-Jensen, D. (2024b). Carbon export from seaweed forests to deep ocean sinks. Nature Geoscience, 17(6), 552–559. Link to source: https://doi.org/10.1038/s41561-024-01449-7

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González-Roca, F., Gelcich, S., Pérez-Ruzafa, Á., Vega, J. M. A., & Vásquez, J. A. (2021). Exploring the role of access regimes over an economically important intertidal kelp species. Ocean & Coastal Management, 212, Article 105811. Link to source: https://doi.org/10.1016/j.ocecoaman.2021.105811

Hanley, M. E., Firth, L. B., & Foggo, A. (2024). Victim of changes? Marine macroalgae in a changing world. Annals of Botany, 133(1), 1–16. Link to source: https://doi.org/10.1093/aob/mcad185

Harley, C. D. G., Anderson, K. M., Demes, K. W., Jorve, J. P., Kordas, R. L., Coyle, T. A., & Graham, M. H. (2012). Effects of climate change on global seaweed communities. Journal of Phycology, 48(5), 1064–1078. Link to source: https://doi.org/10.1111/j.1529-8817.2012.01224.x

Heckwolf, M. J., Peterson, A., Jänes, H., Horne, P., Künne, J., Liversage, K., Sajeva, M., Reusch, T. B. H., & Kotta, J. (2021). From ecosystems to socio-economic benefits: A systematic review of coastal ecosystem services in the Baltic Sea. Science of the Total Environment, 755, Article 142565. Link to source: https://doi.org/10.1016/j.scitotenv.2020.142565

Hurd, C. L., Gattuso, J.-P., & Boyd, P. W. (2024). Air-sea carbon dioxide equilibrium: Will it be possible to use seaweeds for carbon removal offsets? Journal of Phycology, 60(1), 4–14. Link to source: https://doi.org/10.1111/jpy.13405

Kelp Forest Alliance. (2024). State of the world’s kelp report [Report]. Link to source: https://kelpforestalliance.com/state-of-the-worlds-kelp-report/

Krause-Jensen, D., & Duarte, C. M. (2016). Substantial role of macroalgae in marine carbon sequestration. Nature Geoscience, 9(10), 737–742. Link to source: https://doi.org/10.1038/ngeo2790

Krause-Jensen, D., Lavery, P., Serrano, O., Marbà, N., Masque, P., & Duarte, C. M. (2018). Sequestration of macroalgal carbon: The elephant in the blue carbon room. Biology Letters, 14(6), Article 20180236. Link to source: https://doi.org/10.1098/rsbl.2018.0236

Krumhansl, K. A., Okamoto, D. K., Rassweiler, A., Novak, M., Bolton, J. J., Cavanaugh, K. C., Connell, S. D., Johnson, C. R., Konar, B., Ling, S. D., Micheli, F., Norderhaug, K. M., Pérez-Matus, A., Sousa-Pinto, I., Reed, D. C., Salomon, A. K., Shears, N. T., Wernberg, T., Anderson, R. J., … Byrnes, J. E. K. (2016). Global patterns of kelp forest change over the past half-century. Proceedings of the National Academy of Sciences, 113(48), 13785–13790. Link to source: https://doi.org/10.1073/pnas.1606102113

Kumagai, J. A., Goodman, M. C., Villaseñor-Derbez, J. C., Schoeman, D. S., Cavanuagh, K. C., Bell, T. W., Micheli, F., De Leo, G., & Arafeh-Dalmau, N. (2024). Marine protected areas that preserve trophic cascades promote resilience of kelp forests to marine heatwaves. Global Change Biology, 30(12), Article e17620. Link to source: https://doi.org/10.1111/gcb.17620

Lindhart, M., Daly, M. A., Walker, H., Arzeno-Soltero, I. B., Yin, J. Z., Bell, T. W., Monismith, S. G., Pawlak, G., & Leichter, J. J. (2024). Short wave attenuation by a kelp forest canopy. Limnology and Oceanography Letters, 9(4), 478–486. Link to source: https://doi.org/10.1002/lol2.10401

McCrea-Strub, A., Zeller, D., Rashid Sumaila, U., Nelson, J., Balmford, A., & Pauly, D. (2011). Understanding the cost of establishing marine protected areas. Marine Policy, 35(1), 1–9. Link to source: https://doi.org/10.1016/j.marpol.2010.07.001

Ortega, A., Geraldi, N. R., Alam, I., Kamau, A. A., Acinas, S. G., Logares, R., Gasol, J. M., Massana, R., Krause-Jensen, D., & Duarte, C. M. (2019). Important contribution of macroalgae to oceanic carbon sequestration. Nature Geoscience, 12(9), 748–754. Link to source: https://doi.org/10.1038/s41561-019-0421-8

Ortiz‐Villa, E. M., Rassweiler, A., Caselle, J. E., Cavanaugh, K. C., Arafeh‐Dalmau, N., Bell, T. W., & Cavanaugh, K. C. (2025). Marine protected areas enhance climate resilience to severe marine heatwaves for kelp forests. Journal of Applied Ecology, 62(9), 2439–2453. Link to source: https://doi.org/10.1111/1365-2664.70112

Pessarrodona, A., Franco-Santos, R. M., Wright, L. S., Vanderklift, M. A., Howard, J., Pidgeon, E., Wernberg, T., & Filbee-Dexter, K. (2023). Carbon sequestration and climate change mitigation using macroalgae: A state of knowledge review. Biological Reviews, 98(6), 1945–1971.  Link to source: https://doi.org/10.1111/brv.12990

Rodríguez-Rodríguez, D., & Martínez-Vega, J. (2022). Chapter three—Ecological effectiveness of marine protected areas across the globe in the scientific literature. In C. Sheppard (Ed.), Advances in marine biology (Vol. 92, pp. 129–153). Academic Press. Link to source: https://doi.org/10.1016/bs.amb.2022.07.002

Roth, F., Broman, E., Sun, X., Bonaglia, S., Nascimento, F., Prytherch, J., Brüchert, V., Lundevall Zara, M., Brunberg, M., Geibel, M. C., Humborg, C., & Norkko, A. (2023). Methane emissions offset atmospheric carbon dioxide uptake in coastal macroalgae, mixed vegetation and sediment ecosystems. Nature Communications, 14(1), Article 42. Link to source: https://doi.org/10.1038/s41467-022-35673-9

Steen, H., Moy, F. E., Bodvin, T., & Husa, V. (2016). Regrowth after kelp harvesting in Nord-Trøndelag, Norway. ICES Journal of Marine Science, 73(10), 2708–2720. Link to source: https://doi.org/10.1093/icesjms/fsw130

Steneck, R. S., Graham, M. H., Bourque, B. J., Corbett, D., Erlandson, J. M., Estes, J. A., & Tegner, M. J. (2002). Kelp forest ecosystems: Biodiversity, stability, resilience and future. Environmental Conservation, 29(4), 436–459. Link to source: https://doi.org/10.1017/S0376892902000322

Tano, S., Eggertsen, M., Wikström, S. A., Berkström, C., Buriyo, A. S., & Halling, C. (2016). Tropical seaweed beds are important habitats for mobile invertebrate epifauna. Estuarine, Coastal and Shelf Science, 183, 1–12. Link to source: https://doi.org/10.1016/j.ecss.2016.10.010

Thurstan, R. H., Brittain, Z., Jones, D. S., Cameron, E., Dearnaley, J., & Bellgrove, A. (2018). Aboriginal uses of seaweeds in temperate Australia: An archival assessment. Journal of Applied Phycology, 30(3), 1821–1832. Link to source: https://doi.org/10.1007/s10811-017-1384-z

United Nations Environment Programme World Conservation Monitoring Centre, & International Union for Conservation of Nature. (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 April 2024, from Link to source: https://www.protectedplanet.net

United Nations Environment Programme. (2023). Into the blue: Securing a sustainable future for kelp forests [Report]. Link to source: https://wedocs.unep.org/handle/20.500.11822/42331

Waldron, A., Adams, V., Allan, J., Arnell, A., Asner, G., Atkinson, S., Baccini, A., Baillie, J. E. M., Balmford, A., Beau, J. A., Brander, L., Brondizio, E., Bruner, A., Burgess, N., Burkart, K., Butchart, S., Button, R., Carraso, R., Cheung, W., … Zhang, Y. P. (2020). Protecting 30% of the planet for nature: Costs, benefits and economic implications [Report]. Campaign for Nature. Link to source: https://www.conservation.cam.ac.uk/files/waldron_report_30_by_30_publish.pdf

Wong, W. W., Greening, C., Shelley, G., Lappan, R., Leung, P. M., Kessler, A., Winfrey, B., Poh, S. C., & Cook, P. (2021). Effects of drift algae accumulation and nitrate loading on nitrogen cycling in a eutrophic coastal sediment. Science of The Total Environment, 790, Article 147749. Link to source: https://doi.org/10.1016/j.scitotenv.2021.147749

Credits

Lead Fellow

  • Christina Richardson, Ph.D.

Contributors

  • Ruthie Burrows, Ph.D.

  • Avery Driscoll, Ph.D.

  • James Gerber, Ph.D.

  • Daniel Jasper

  • Alex Sweeney

Internal Reviewers

  • Aiyana Bodi

  • Avery Driscoll, Ph.D.

  • Christina Swanson, Ph.D.

  • Paul C. West, Ph.D.

Effectiveness

The globally weighted average effectiveness of seaweed ecosystem protection is 0.32 tCO₂‑eq /ha/yr. Protecting 1 ha of seaweed ecosystem avoids emissions of 0.043–0.13 tCO₂‑eq /ha/yr while also sequestering an additional 0.083–0.43 tCO₂‑eq /ha/yr, with effectiveness higher in subtidal brown than subtidal red seaweed ecosystems (100-yr GWP; Table 1; Appendix).

We estimated effectiveness as the avoided emissions and retained carbon sequestration capacity attributable to the reduction in seaweed ecosystem loss conferred by protection, as detailed in Equation 1. First, we calculated the difference between the rate of seaweed ecosystem loss outside and inside MPAs (Seaweed lossbaseline). We assumed a reduction in loss of 53% (Reduction in loss), which is based on estimates for a range of ecosystems in MPAs (Rodríguez-Rodríguez & Martínez-Vega, 2022). Importantly, this number is highly uncertain and likely to be highly variable, too. 

Next, we multiplied this product by the sum of the avoided CO₂ emissions associated with the one-time loss of all above ground biomass carbon in 1 ha of seaweed ecosystem each year over 30 years (Carbonavoided emissions) and the amount of carbon sequestered via long-term storage (on-site or off-site) in 1 ha of protected seaweed ecosystem each year over 30 years (Carbonsequestration). 

We based these rates on original analysis of a subset of studies conducted over, at least, 20 years, collated from Krumhansl et al. (2016), that show a median loss rate of 1.2% per year for kelp forests. Due to data limitations, we applied this loss rate to subtidal red seaweed ecosystems as well, but recognize that loss rates are likely to be highly variable. We did this calculation separately for red and brown seaweed ecosystems due to their distinct biomass densities and sequestration capacities, and then averaged the results with accommodations for their relative global areas.

Equation 1.

\[ \text{Effectiveness} = \left( \text{Seaweed loss}_{\text{baseline}} \times \text{Reduction in loss} \right) \times \left( \text{Carbon}_{\text{avoided emissions}} + \text{Carbon}_{\text{sequestration}} \right) \]

Table 1. Effectiveness of seaweed ecosystem protection in avoiding emissions and sequestering carbon.

Unit: tCO₂‑eq /ha/yr, 100-year basis

Avoided emissions, estimate 0.13
Sequestration 0.43
Total effectiveness, estimate 0.56
Total effectiveness, 25th percentile 0.21
Total effectiveness, 75th percentile 0.91

Unit: tCO₂‑eq /ha/yr, 100-year basis

Avoided emissions, estimate 0.043
Sequestration 0.083
Total effectiveness, estimate 0.13
Total effectiveness, 25th percentile 0.034
Total effectiveness, 75th percentile 0.22

Unit: tCO₂‑eq /ha/yr, 100-year basis

Avoided emissions, estimate 0.080
Sequestration 0.24
Total effectiveness, estimate 0.32
Total effectiveness, 25th percentile 0.11
Total effectiveness, 75th percentile 0.52
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Cost

We estimate that seaweed ecosystem protection might save approximately US$72/tCO₂‑eq , but emphasize that these estimates are highly uncertain due to existing data limitations. This is based on protection costs of roughly US$14/ha/yr and revenue of US$43/ha/yr compared with the baseline (Table 2). The costs of seaweed ecosystem protection also include up-front one-time expenditures of US$208 (surveys, administrative setup, legal fees, etc.), estimated from McCrea-Strub et al. (2011). However, data related to the costs of seaweed ecosystem protection are limited, and these estimates are uncertain. For consistency across solutions, we did not include revenue associated with other ecosystem services. 

We estimated costs of MPA maintenance at US$14/ha/yr based on data from existing MPAs, though only 16% of MPAs surveyed reported their current funding was sufficient (Balmford et al., 2004). Maintenance is critical for seaweed ecosystems, especially those prone to overgrazing. Tourism revenues directly attributable to protection were estimated to be $43/ha/yr (Waldron et al., 2020) based on estimates for all MPAs (and PAs) and not including downstream revenues. However, estimates of tourism revenues are highly uncertain for seaweed ecosystems. In some seaweed ecosystems, such as kelp forests, tourism is likely a real revenue generator through diving or other recreational activities, but the financial contribution is generally unclear and poorly documented across all seaweed ecosystems. 

Table 2. Cost per unit of climate impact. Negative values indicate cost savings.

Unit: 2023 US$/tCO₂‑eq , 100-yr basis

Estimate -72
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Methods and Supporting Data

Methods and Supporting Data

Learning Curve

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

Speed of Action

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

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

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

Caveats

Additionality is an important caveat for ecosystem protection. In our analysis, we used baseline rates of seaweed ecosystem loss to calculate the effectiveness of protection, which are highly uncertain and understudied. This assumes that seaweed ecosystems would continue to be lost at these rates in the absence of protection and thus that protection provides additional carbon benefits from the ecosystems whose loss is avoided. 

Importantly, effective protection depends on adequate funding and management. Poorly managed MPAs can fail to prevent key stressors, such as urchin overgrazing, from increasing and undermine the viability of seaweed ecosystems. Similar dynamics have been documented in kelp restoration efforts, where inadequate management has led to overgrazing and project failure (Eger et al., 2022).

The permanence of ecosystem carbon benefits is another key caveat. While seaweed ecosystems are expanding or expected to expand with climate change, in some regions many will contract (Corrigan et al., 2025). Protection may increase resilience to some climate change stressors, but it will not fully prevent ecosystem loss in many regions. Additionally, because seaweed ecosystems sequester carbon both on-site and off-site, the effectiveness of protection partly depends on downstream activities. For instance, carbon at the seafloor is threatened by disturbances such as bottom fishing and mining (see Protect Seafloors). Protection of seaweed ecosystems does not prevent loss of downstream stored carbon, some of which is contributed by seaweed ecosystems (Ortega et al., 2019). Additionally, seaweed biomass extent can change dramatically from year to year, which could result in substantial variability in carbon removal rates despite protection.

Another caveat in this solution lies in our assumptions about carbon dynamics at the ocean surface. We assume that seaweed NPP results in an equivalent removal of CO₂ from the atmosphere. In reality, this influx may not be fully efficient (Hurd et al., 2024). In some regions of the ocean, water carrying a CO₂ deficit from seaweed photosynthesis might be subducted before it reaches equilibrium with the atmosphere, which would reduce the atmospheric removal attributed to seaweed productivity in our calculations.

In our analysis, avoided emissions are calculated under the assumption that destruction of a seaweed ecosystem results in the loss of all biomass carbon This likely overestimates near-term emissions, as some carbon may remain in the ocean for long periods. However, this fraction is expected to be small given that an estimated 6.0–13.7% (average: 11.4%) of NPP is thought to be stored long term (Krause-Jensen & Duarte, 2016). 

Finally, the relative fraction of NPP removed and durably stored (>100 years) is also uncertain (Pessarrodona et al., 2023). Despite this uncertainty, our use of 11.4% is supported by recent modeling of particulate carbon fluxes that suggest ~12.5% of NPP could be sequestered on a 100-year timescale (based on 44 Tg C of particulate organic carbon export to 1,000 m, where carbon is less likely to return to the atmosphere within a century, and ~353 Tg C as NPP; Filbee-Dexter et al., 2024b), but requires more research.

Current Adoption

A total of 78.80 Mha of seaweed ecosystems are currently within MPAs (Table 3). Cumulatively, roughly 18% of seaweed ecosystems are under some form of protection, with 4% located in strictly protected MPAs, 6% in nonstrict MPAs, and 8% in other IUCN protection categories. Subtidal brown and red seaweed ecosystems have similar rates of existing protection in all protection categories (Figure 3).

Table 3. Current (circa 2024) extent of seaweed ecosystems under legal protection. “Strict protection” includes land within IUCN categories I–II Marine Protected Areas (MPAs). “Nonstrict protection” includes land within IUCN Categories III–VI MPAs. “Other” includes land within all remaining IUCN MPA categories. Values may not sum to global totals due to rounding.

Unit: Mha protected

Strict protection 8.43
Nonstrict protection 11.4
Other 15.5
Total 35.3

Unit: Mha protected

Strict protection 9.28
Nonstrict protection 16.3
Other 18.0
Total 43.5

Unit: Mha protected

Strict protection 17.7
Nonstrict protection 27.6
Other 33.4
Total 78.8
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Adoption Trend

We calculated the rate of MPA expansion in seaweed ecosystems based on recorded year of establishment (UNEP-WCMC & IUCN, 2024). Protection expanded by a median of 0.74 Mha/yr in subtidal brown seaweed ecosystems and 0.97 Mha/yr in subtidal red seaweed ecosystems (Table 4; Figure 3a). The global average rate of expansion was roughly 2.13 Mha/yr, with a median of 1.71 Mha/yr. The adoption trend for subtidal brown and red seaweed was relatively similar, with both expanding 0.46–0.55%/yr, on average (median of 0.39–0.40%/yr) (Figure 3b).

Table 4. 2000–2024 adoption trend. Global totals reflect independent statistics, not sums of subtidal brown and red values.

Unit: Mha/yr

25th percentile 0.40
Median (50th percentile) 0.74
Mean 1.01
75th percentile 1.31

Unit: Mha/yr

25th percentile 0.62
Median (50th percentile) 0.97
Mean 1.12
75th percentile 1.45

Unit: Mha/yr

25th percentile 1.02
Median (50th percentile) 1.71
Mean 2.13
75th percentile 2.76
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Figure 3. Trend in seaweed ecosystem protection (2000–2024) in terms of (A) total hectares protected and (B) the percent of the current adoption ceiling that is currently protected. These values reflect only the area located within Marine Protected Areas. Units: million hectares protected and percent protected relative to the adoption ceiling.

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Adoption Ceiling

We estimated that approximately 430 Mha of wild seaweed ecosystems are available for protection (Table 5). Subtidal red seaweeds compose ~240 Mha, with subtidal brown seaweeds occupying the remaining ~190 Mha. These adoption areas do not include other types of seaweed habitats/ecosystems, such as those found in the intertidal zone, rhodolith beds, Halimeda bioherms, coral reefs, and pelagic, free-floating seaweed, which could account for an additional ~150 Mha (Duarte et al., 2022). These adoption areas are highly uncertain due to data limitations and are also likely to shift with climate change.

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

Unit: Mha

Estimate 189.6

Unit: Mha

Estimate 243.0

Unit: Mha

Estimate 432.6
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Achievable Adoption

We defined the lower end of the achievable range for seaweed ecosystem protection (across all IUCN categories) as 50% of the adoption ceiling and the upper end of the achievable range as 70% of the adoption ceiling (Table 6). These adoption levels are ambitious relative to existing levels of protection (~18%), but align with targets to protect 30% of ecosystems by 2030 (Eger et al., 2024) and serve as an optimistic benchmark for the 30-year time horizon considered in our analysis. Several countries already protect more than 30% of subtidal brown seaweed ecosystems, such as kelp forests (Kelp Forest Alliance, 2024). For example, the United Kingdom, Japan, China, and France protect over 41%, 68%, 68%, and 47% of their kelp beds, respectively. 
 

Table 6: Range of achievable adoption levels for seaweed ecosystems.

Unit: Mha

Current adoption 78.8
Achievable – low 216.3
Achievable – high 302.9
Adoption ceiling 432.6
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We estimated that MPAs currently avoid emissions of 0.03 GtCO₂‑eq/yr in seaweed ecosystems, with potential impacts of 0.14 GtCO₂‑eq/yr at the adoption ceiling (Table 7). Achievable levels of seaweed ecosystem protection could safeguard 0.07 to 0.10 GtCO₂‑eq/yr by reducing emissions from biomass loss and retaining sequestration fluxes (Table 7). However, these estimates are highly uncertain and will benefit from more research (see Caveats).

Limited data exist on the potential climate impacts of seaweed ecosystem protection for comparison. However, a rough estimate of the benefits of conservation, restoration, and afforestation interventions of seaweeds suggests carbon benefits of at least 0.04 GtCO₂‑eq/yr (Pessarrodona et al., 2023). Other estimates suggest that total carbon sequestration in seaweed ecosystems could be on the order of 0.22–0.98 GtCO₂‑eq/yr (Krause-Jensen & Duarte, 2016). This is higher than our estimates because we account only for the carbon benefits of protection in seaweed ecosystems at risk of loss.

Table 7. Climate impact at different levels of adoption. Values may not sum to global totals due to rounding.

Unit: GtCO₂‑eq/yr, 100-year basis

Current adoption 0.02
Achievable – low 0.05
Achievable – high 0.07
Adoption ceiling 0.11

Unit: GtCO₂‑eq/yr, 100-year basis

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

Unit: GtCO₂‑eq/yr, 100-year basis

Current adoption 0.03
Achievable – low 0.07
Achievable – high 0.10
Adoption ceiling 0.14
Left Text Column Width
Additional Benefits

Extreme Weather Events

Seaweeds can provide coastal resilience to the impacts of storms by lowering wave heights before they reach shorelines (Corrigan et al., 2025; Cotas et al., 2023). The magnitude of this benefit can vary based on the species and location of seaweed, and some evidence suggests that severe storms can harm seaweed habitats (Earp et al., 2024). Evidence suggests that kelp forests can attenuate wave heights locally, especially in the summer at peak kelp growth, but protection varies at larger spatial scales (Elsmore et al., 2024; Lindhart et al., 2024). Emerging research has found that protected seaweed ecosystems show more resilience to marine heat waves than unprotected areas (Kumagai et al., 2024). During heat waves, protected ecosystems maintain a habitat for species such as sea urchins that consume species that might degrade kelp ecosystems (Bauer et al., 2025; Kumagai et al., 2024).

Income and Work

Seaweeds support species that are important for tourism and fishing (Cuba et al., 2022; Eger et al., 2023). Many species that are supported by seaweeds have high economic value for fishing, such as crabs, lobsters, and abalones (Corrigan et al., 2025). For example, Eger et al. (2023) estimated that 1 ha of kelp forest where about 900 kg of fish biomass is harvested could yield about US$29,900 a year. The same study estimated that the global value of kelp forests that support fisheries is about US$465–562 billion (Eger et al., 2023). Seaweed habitats can also be tourist destinations for snorkeling and diving (UNEP, 2023), providing income-earning opportunities for nearby communities.

Food Security

The contribution of seaweeds to fisheries production can play a role in global food security (Cottier-Cook et al., 2023; Eger et al., 2023). Additionally, seaweeds are an essential part of many diets, especially in East Asia (FAO, 2024). Because seaweeds are a culturally important food in many geographies, protecting seaweeds can play an important role in equitably improving global food security (FAO, 2024).

Equality

For some cultures, seaweeds and their habitats shape shared identities and livelihoods (Cotas et al., 2023). For example, seaweeds are a source of traditional foods, medicines, art, and knowledge for many coastal communities and Indigenous peoples (Thurstan et al., 2018). Protecting seaweeds can preserve the cultural identities, practices, and knowledge of Indigenous communities that are often vulnerable (Corrigan et al., 2025).

Nature Protection

Seaweeds support biodiversity by providing habitat for a variety of marine species (Best et al., 2014; Cuba et al., 2022; Gibbons & Quijón, 2023; Tano et al., 2016). Literature reviews of the ecosystem services of seaweeds find that they contribute to increases in biodiversity (Gibbons & Quijón, 2023). Seaweeds can provide habitat and refuge from large predators (Best et al., 2014; Gibbons & Quijón, 2023). Invertebrates, detritivores, and other small species found in seaweed forests are essential food sources for other marine species (Cuba et al., 2022; Tano et al., 2016). 

Water Quality

Seaweeds improve water quality by supporting nutrient cycling and reducing pollutants (Cotas et al., 2023; Heckwolf et al., 2021). Evidence suggests that seaweeds can reduce eutrophication by filtering excess nutrients from the water (Corrigan et al., 2025; Gao et al., 2022; Heckwolf et al., 2021). 

Risks

Leakage, in which protecting one ecosystem results in the degradation of another, could offset the climate impact of seaweed ecosystem protection. For instance, restricting wild harvesting through the establishment of an MPA could shift pressure to other unprotected areas. Another key risk is weakly enforced or poorly managed MPAs. This is a real concern with existing MPAs due to a lack of funding, and can result in low protection effectiveness. Finally, climate change stressors, such as ocean warming and marine heat waves, are a major risk to permanence because they could lead to widespread mortality, even in protected areas.

Interactions with Other Solutions

Reinforcing

Intact and healthy seaweed ecosystems can enhance fish stocks, biodiversity, and habitat quality, which benefits all connected coastal and marine ecosystems.

Protecting seaweed ecosystems can help ensure the underlying areas of the seafloor remain intact.

Competing

Protection of seaweed ecosystems could potentially reduce the adoption of offshore wind in some regions.

Dashboard

Solution Basics

ha of seaweed ecosystem protected

t CO₂-eq (100-yr)/unit/yr
00.110.32estimate
units
Current 7.88×10⁷ 02.163×10⁸3.029×10⁸
Achievable (Low to High)

Climate Impact

Gt CO₂-eq (100-yr)/yr
Current 0.03 0.070.1
US$ per t CO₂-eq
-72
Emergency Brake

CO₂

Trade-offs

Seaweed ecosystems can release methane, which could reduce the climate benefits of protection estimated in this solution. While data are scarce, a recent study suggests that methane emissions could offset 28–35% of the carbon sink capacity in some seaweed ecosystems (Roth et al., 2023) if they escape to the atmosphere, which may be unlikely if methane production occurs at depth in sediments (Pessarrodona et al., 2023). 

Action Word
Protect
Solution Title
Seaweed Ecosystems
Classification
Highly Recommended
Lawmakers and Policymakers
  • Set achievable targets and pledges for seaweed protection with clear effectiveness goals; regularly measure and report on protection status, seaweed ecosystems, challenges, and related data points.
  • Help develop definitions, standards, strategies, and commitments at the international level for seaweed protection along with frameworks for measurement and monitoring; design indicators to capture long-term impacts, including metrics to capture social and biodiversity impacts.
  • Establish MPAs specifically for seaweeds and their habitats; target subtidal brown seaweeds for maximum climate benefits while not neglecting others such as red seaweeds; incorporate statutory protections for seaweeds in existing MPAs; expand MPA designations to meet international goals.
  • Create strong regulatory frameworks with clear goals and definitions for activities related to seaweed protection such as sustainable harvesting, protection, management, and restoration; ensure the framework is gender responsive and seeks to include women throughout the protection process.
  • Seek to identify local drivers of seaweed decline, address drivers of decline through stringent legal protections, ensure strict enforcement of regulations, and allow for restoration activities.
  • When designating new MPAs, prioritize strategies such as no-take-fishing regulations and strong enforcement measures with high penalties for noncompliance; target large (>100 km2) areas that can be protected over the long term (>10 years) and are ecologically isolated by natural barriers such as deep water and/or sand.
  • Consider placing MPAs near protected or undisturbed terrestrial areas to help avoid nutrient and other land pollution.
  • Codesign seaweed protection projects with the local community; ensure the community engagement process starts early and is transparent, inclusive, and ongoing; solicit feedback from the local community – including from opposition groups – on location, design, finance, and management; ensure finalized protections address sociological, economic, and ecological considerations.
  • Coordinate seaweed protection and restoration policies horizontally (e.g., across agencies) and vertically (e.g., across subnational, national, and international efforts); seek to align social and environmental safeguards with seaweed protection policies and goals.
  • Develop regional and transboundary coordination mechanisms for seaweed protection, especially when working across international borders; consider using proven methods from adjacent issue areas such as freshwater management or combining MPA management with existing coordinating bodies.
  • Review MPA management plans, regulations, designs, and implementation strategies frequently to adjust for changing conditions; update as needed and ensure protections allow for changes to respond to climatic conditions.
  • Ensure projects operating in or with Indigenous communities only do so under Free, Prior, and Informed Consent (FPIC); codify FPIC into legal systems.
  • Strengthen land tenure rights; grant Indigenous communities full property rights and autonomy to protect coastal areas and watersheds.
  • Center Indigenous communities and knowledge in MPA management strategies; help document and amplify Indigenous wisdom and practices.
  • Create programs to monitor for activity and market leakage from protected sites; adjust enforcement and policies to reduce leakage, if necessary.
  • Maintain up-to-date records of seaweed harvesting and populations; monitor impacts; adjust regulations and enforcement to ensure harvesting is sustainable.
  • Remove harmful agriculture subsidies, particularly those that incentivize livestock and overuse of fertilizers that can impact seaweed habitats and MPAs.
  • Put into place locally relevant laws and regulations that help indirectly protect seaweed ecosystems, such as bans on sea otter trapping or bottom trawling.
  • Create “climate-smart” MPAs that connect seaweed ecosystems, allow for gene exchanges, and adjust boundaries to address changing oceanic conditions; target protection of taxa such as brown seaweedss that maximize climate benefits while not neglecting others such as red seaweeds; incorporate climate refugia into MPAs; create strategies for MPAs to address both climate mitigation and adaptation.
  • Invest in research on seaweed biodiversity seeking to document new species, sample from underrepresented regions, and use the most up-to-date techniques to assess taxonomies; support efforts to update key databases such as the IUCN Red List; support research to improve confidence in estimates of global seaweed ecosystem extent, biomass, composition, productivity, and loss rates; monitor related long-term trends.
  • Create educational and volunteer programs that work with schools, universities, NGOs, and the general public to inform communities how to participate in seaweed protection efforts, benefits, and opportunities; expand extension services to develop local capacity in seaweed protection, especially in community-led monitoring and evaluation; establish knowledge-sharing initiatives with Indigenous peoples.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Practitioners
  • Set achievable targets and pledges for seaweed protection with clear effectiveness goals; regularly measure and report on protection status, seaweed ecosystems, challenges, and related data points.
  • Help develop definitions, standards, strategies, and commitments at the international level for seaweed protection along with frameworks for measurement and monitoring; design indicators to capture long term impacts, including metrics to capture social and biodiversity impacts.
  • Establish MPAs specifically for seaweeds and their habitats; target subtidal brown seaweeds for maximum climate benefits while not neglecting others such as red seaweeds; incorporate statutory protections for seaweeds in existing MPAs; expand MPA designations to meet international goals.
  • Help create strong regulatory frameworks with clear goals and definitions for activities related to seaweed protection such as sustainable harvesting, protection, management, and restoration; ensure the framework is gender responsive and seeks to include women throughout the protection process.
  • Seek to identify local drivers of seaweed decline, address drivers of decline through stringent legal protections, ensure strict enforcement of regulations, and allow for restoration activities.
  • When designating new MPAs, prioritize strategies such as no-take-fishing regulations and strong enforcement measures with high penalties for noncompliance; target large (>100 km2) areas that can be protected over the long term (>10 years) and are ecologically isolated by natural barriers such as deep water and/or sand.
  • Create “climate-smart” MPAs that connect seaweed ecosystems, allow for gene exchanges, and adjust boundaries to address changing oceanic conditions, target protection of taxa such as brown seaweeds that maximize climate benefits while not neglecting others such as red seaweeds; incorporate climate refugia into MPAs; create specific strategies for MPAs to address both climate mitigation and adaptation.
  • Consider placing MPAs near protected or undisturbed terrestrial areas to help avoid nutrient and other land pollution.
  • Codesign seaweed protection projects with the local community; ensure the community engagement process starts early and is transparent, inclusive, and ongoing; solicit feedback from the local community – including from opposition groups – on location, design, finance, and management; ensure finalized protections address sociological, economic, and ecological considerations.
  • Develop regional and transboundary coordination mechanisms for seaweed protection - especially, when working across international borders; consider using proven methods from adjacent issue areas such as fresh-water management or combining MPA management with existing coordinating bodies.
  • Review MPA management plans, regulations, designs, and implementation strategies frequently to adjust for changing conditions; update as needed and ensure protections allow for changes to respond to climatic conditions.
  • Maintain detailed financial records of activities related to MPA designation and management; share costs publicly and provide recommendations for best practices.
  • Ensure projects operating in or with Indigenous communities only do so under FPIC; help codify FPIC into legal systems.
  • Center Indigenous communities and knowledge in MPA management strategies; help document and amplify Indigenous wisdom and practices.
  • Work with businesses to develop markets for native species products and other sustainable uses of seaweed and MPAs.
  • Develop or support opportunities for ecotourism industries in local MPAs with particular emphasis on educating tourists of the importance of seaweed.
  • Create programs to monitor for activity and market leakage from protected sites; adjust enforcement and strategies to reduce leakage, if necessary.
  • Maintain up-to-date records of seaweed harvesting and existing populations; monitor impacts; adjust regulations and enforcement to ensure harvesting is sustainable.
  • Invest in research on seaweed biodiversity seeking to document new species, sample from underrepresented regions, and use the most up-to-date techniques to assess taxonomies; support efforts to update key databases such as the IUCN Red List; support research to improve confidence in estimates of global seaweed ecosystem extent, biomass, composition, productivity, and loss rates; monitor related long-term trends.
  • Create educational and volunteer programs that work with schools, universities, NGOs, and the general public to inform communities of how to participate in seaweed protection efforts, benefits, and opportunities; expand extension services to develop local capacity in seaweed protection, especially in community-led monitoring and evaluation; establish knowledge-sharing initiatives with Indigenous peoples.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Business Leaders
  • Ensure operations, development, and supply chains are not degrading seaweed communities or interfering with MPA management.
  • Develop markets for native species products and other sustainable uses of seaweed and MPAs.
  • Develop or support opportunities for ecotourism industries in local MPAs with particular emphasis on educating tourists of the importance of seaweed.
  • Consider offering company grants to suppliers or other partners to improve resource management within your supply chain.
  • Offer incubator services for those working on seaweed protection; offer pro bono business advice or general support for community protection efforts.
  • Enter into outgrower schemes to support sustainable harvesters; make long-term commitments to help stabilize projects.
  • Consider donating or contributing to local seaweed protection efforts; consider using an internal carbon fee or setting aside a percentage of revenue to fund protection projects.
  • 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 seaweed protection policies at national and international levels.
  • Offer employee professional development funds to be used for certification in seaweed protection or related fields such as curricular economies.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Nonprofit Leaders
  • Ensure operations, development, and supply chains are not degrading seaweed communities or interfering with MPA management, if relevant.
  • Assist in managing restoration projects; consider using alternative business structures such as cooperatives.
  • Develop seaweed protection tool kits specific for nations or regions; include best practices, management strategies, typical interventions, recommendations for regulations, and strategies for civil society to impact legal classifications and MPA designations.
  • Advocate for achievable targets and pledges for seaweed protection with clear effectiveness goals; help regularly measure and report on protection status, seaweed ecosystems, challenges, and related data points.
  • Help develop definitions, standards, strategies, and commitments at the international level for seaweed protection along with frameworks for measurement and monitoring; design indicators to capture long-term impacts, including metrics to capture social and biodiversity impacts.
  • Establish or advocate for the establishment of MPAs specifically for seaweeds and their habitats; target subtidal brown seaweeds for maximum climate benefits while not neglecting others such as red seaweeds; advocate for statutory protections for seaweeds in existing MPAs; help expand MPA designations to meet international goals.
  • Help create strong regulatory frameworks with clear goals and definitions for activities related to seaweed protection such as sustainable harvesting, protection, management, and restoration; ensure the framework is gender responsive and seeks to include women throughout the protection process.
  • Seek to identify local drivers of seaweed decline, help address causes when possible, and advocate for stringent legal protections with strict enforcement.
  • Help develop or advocate for regional and transboundary coordination mechanisms for protecting seaweeds, especially when working across international borders; consider using proven methods from adjacent issue areas such as freshwater management or combining MPA management with existing coordinating bodies.
  • Help review MPA management plans, regulations, designs, and implementation strategies frequently to adjust for changing conditions; update as needed and ensure protections allow for changes to respond to climatic conditions.
  • Codesign seaweed protection projects with the local community; ensure the community engagement process starts early and is transparent, inclusive, and ongoing; solicit feedback from the local community – including from opposition groups–- on location, design, finance, and management strategies; ensure finalized protections address relevant sociological, economic, and ecological considerations.
  • Help maintain and/or audit detailed financial records of activities related to MPA designation and management; share costs publicly and provide recommendations for best practices.
  • Ensure projects operating in or with Indigenous communities only do so under FPIC; advocate to codify FPIC into legal systems.
  • Center Indigenous communities and knowledge in MPA management strategies; help document and amplify Indigenous wisdom and practices.
  • Work with businesses to develop markets for native species products and other sustainable uses of seaweed and MPAs.
  • Develop or support opportunities for ecotourism industries in local MPAs with particular emphasis on educating tourists of the importance of seaweed.
  • Create programs to monitor for activity and market leakage from protected sites; advocate for adjustments to enforcement and policies to reduce leakage, if necessary.
  • Help establish outgrower schemes and negotiate contracts to support sustainable harvesters to ensure they receive the most favorable terms possible.
  • Assist in maintaining up-to-date records of seaweed harvesting and existing ecosystems; monitor impacts; advocate for adjustments to regulations and enforcement to ensure harvesting is sustainable.
  • Help create educational and volunteer programs that work with schools, universities, other NGOs, and the general public to inform communities of how to participate in seaweed protection efforts, benefits, and opportunities; develop local capacity in seaweed protection, especially in community-led monitoring and evaluation; establish knowledge-sharing initiatives with Indigenous peoples.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Investors
  • Create investment portfolios that support seaweed protection and sustainable use; use current data and the latest technology to guide sustainable investments.
  • Apply environmental and social standards to existing investments; divest from destructive industries and/or work with portfolio companies to improve practices.
  • Offer specific credit lines for seaweed protection projects with long-term timelines; offer low-interest loans, microfinancing, and specific financial products for small and medium-sized projects.
  • Own equity in sustainable projects that manage or support seaweed protection, especially during the early and middle phases.
  • Offer incubator services for those working on seaweed protection; offer pro bono business advice or general support for community protection projects.
  • Provide catalytic financing for businesses developing sustainable products made from native species, local ecotourism, or other sustainable uses of seaweed and MPAs.
  • Invest in blue bonds or high-integrity carbon credits for seaweed protection or supportive efforts.
  • Support seaweed protection, other investors, and NGOs by sharing data, information, and investment frameworks that successfully avoid investments that drive declines in seaweeds and damage their habitats.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Philanthropists and International Aid Agencies
  • Ensure operations, development, and supply chains are not degrading seaweed communities or interfering with MPA management, if relevant.
  • Help manage restoration projects; consider using alternative business structures such as cooperatives.
  • Offer grants or specific credit lines for seaweed protection projects with long-term timelines; offer low-interest loans, microfinancing options, and favorable financial products for small and medium-sized projects.
  • Own equity in sustainable projects that manage or support seaweed protection, especially during the early and middle phases.
  • Offer incubator services for those working on seaweed protection; offer free business advice or general support for community protection projects.
  • Provide catalytic financing for business developing sustainable products made from native species, local ecotourism, or other sustainable uses of reforested lands.
  • Develop seaweed protection tool kits specific for nations or regions; include best practices, management strategies, typical interventions, recommendations for regulations, and strategies for civil society to impact legal classifications and MPA designations.
  • Advocate for achievable targets and pledges for seaweed protection with clear effectiveness goals; help regularly measure and report on protection status, seaweed ecosystems, challenges, and related data points.
  • Help develop definitions, standards, strategies, and commitments at the international level for seaweed protection along with frameworks for measurement and monitoring; design indicators to capture long-term impacts, including metrics to capture social and biodiversity impacts.
  • Establish or advocate for the establishment of MPAs specifically for seaweeds and their habitats; target subtidal brown seaweeds for maximum climate benefits while not neglecting other taxa such as red seaweeds; advocate for statutory protections for seaweeds in existing MPAs; help expand MPA designations to meet international goals.
  • Help create strong regulatory frameworks with clear goals and definitions for activities related to seaweed protection such as sustainable harvesting, protection, management, and restoration; ensure the framework is gender responsive and seeks to include women throughout the protection process.
  • Help develop or advocate for regional and transboundary coordination mechanisms for protecting seaweeds, especially when working across international borders; consider using proven methods from adjacent issue areas such as freshwater management or combining MPA management with existing coordinating bodies.
  • Help review MPA management plans, regulations, designs, and implementation strategies frequently to adjust for changing conditions; update as needed and ensure protections allow for changes to respond to climatic conditions.
  • Help maintain and/or audit detailed financial records of activities related to MPA designation and management; share costs publicly and provide recommendations for best practices.
  • Ensure projects operating in or with Indigenous communities only do so under FPIC; advocate to codify FPIC into legal systems.
  • Center Indigenous communities and knowledge in MPA management strategies; help document and amplify Indigenous wisdom and practices.
  • Work with businesses to develop markets for native species products and other sustainable uses of seaweeds and MPAs.
  • Develop or support opportunities for ecotourism industries in local MPAs with particular emphasis on educating tourists of the importance of seaweed.
  • Create programs to monitor for activity and market leakage from protected sites; advocate for adjustments to enforcement and policies to reduce leakage, if necessary.
  • Help establish outgrower schemes and negotiate contracts to support sustainable harvesters to ensure they receive the most favorable terms possible.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Thought Leaders
  • If possible, initiate seaweed protection projects in your area; work with local experts, share your experience, and document your progress.
  • Advocate for achievable targets and pledges for seaweed protection with clear effectiveness goals; help regularly measure and report on protection status, seaweed ecosystems, challenges, and related data points.
  • Help develop definitions, standards, strategies, and commitments at the international level for seaweed protection along with frameworks for measurement and monitoring; design indicators to capture long-term impacts, including metrics to capture social and biodiversity impacts.
  • Establish or advocate for the establishment of MPAs specifically for seaweeds and their habitats; target subtidal brown seaweeds for maximum climate benefits while not neglecting others such as red seaweeds; advocate for statutory protections for seaweeds in existing MPAs; help expand MPA designations to meet international goals.
  • Help create strong regulatory frameworks with clear goals and definitions for activities related to seaweed protection such as sustainable harvesting, protection, management, and restoration; ensure the framework is gender responsive and seeks to include women throughout the protection process.
  • Help develop or advocate for regional and transboundary coordination mechanisms for protecting seaweeds, especially, when working across international borders; consider using proven methods from adjacent issue areas such as freshwater management or combining MPA management with existing coordinating bodies.
  • Help review MPA management plans, regulations, designs, and implementation strategies frequently to adjust for changing conditions; update as needed and ensure protections allow for changes to respond to climatic conditions.
  • Ensure projects operating in or with Indigenous communities only do so under FPIC; advocate to codify FPIC into legal systems.
  • Center Indigenous communities and knowledge in MPA management strategies; help document and amplify Indigenous wisdom and practices.
  • Work with businesses to develop markets for native species products and other sustainable uses of seaweeds and MPAs.
  • Develop or support opportunities for ecotourism industries in local MPAs with particular emphasis on educating tourists of the importance of seaweed.
  • Create programs to monitor for activity and market leakage from protected sites; advocate for adjustments to enforcement and policies to reduce leakage, if necessary.
  • Help establish outgrower schemes and negotiate contracts to support sustainable harvesters to ensure they receive the most favorable terms possible.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Technologists and Researchers
  • Help develop spatial distribution models of seaweed ecosystems combining field surveys, satellite data, and machine learning to help identify likely locations of seaweed and vulnerable ecosystems; conduct field observations to validate and/or improve models; update existing or create new databases with the information.
  • Help improve confidence in estimates of global seaweed ecosystems and monitor related long-term trends, including impacts of harvesting and adaptive capacity of seaweeds.
  • Conduct research on seaweed biodiversity seeking to document new species, sample from underrepresented regions, and use the most up-to-date techniques to assess taxonomies; help update key databases such as the IUCN Red List.
  • Help develop national seedstocks and biosecure nurseries for local and vulnerable seaweed.
  • Research the interactions of disturbances such as overfishing, eutrophication, coastal darkening, invasive species, climate change, and other related variables on seaweed ecosystems; identify loss rates and protection strategies to mitigate impacts from these events.
  • Examine and document ecosystem functions of various seaweed varieties, including their productivity and potential contributions to carbon removal; research the benefits of seaweed protection for human well-being.
  • Help classify existing MPAs according to IUCN categories; monitor ongoing efforts; use learnings to inform management.
  • Help gather accurate financial data on MPAs; assess average and global costs; provide cost projections for potential MPA sites; assess financial gains provided by MPAs, such as increased tourism and economic activity.
  • Work with Indigenous communities under FPIC to help document, examine, and apply traditional practices; help amplify relevant Indigenous knowledge.

Further information:

Communities, Households, and Individuals
  • If possible, initiate seaweed protection projects in your area; work with local experts, share your experience, and document your progress.
  • Help establish and participate in local protection efforts; consider volunteering with a local nonprofit or establishing one if none exists.
  • Conduct citizen science research to map and monitor local seaweed communities; share your findings with policymakers, local experts, and the public.
  • If seaweed communities are being damaged in your area and no action is being taken, conduct individual advocacy by speaking to local officials, handing out fliers, and other relevant methods.
  • Help identify local sources of degradation and distribute findings to policymakers and the public; help address causes when possible and advocate for stringent legal protections with strict enforcement.
  • Call on governments and administrators to use transparent, inclusive, and ongoing community engagement processes to codesign seaweed protection projects; help solicit community feedback on area designations, finance, monitoring, and distribution of benefits; help ensure finalized projects address relevant sociological, economic, and ecological considerations.
  • Reduce and/or eliminate use of chemicals on your lawn and/or property to reduce pollution runoff, especially if your property contains or is located on a coastally connected watershed; set up a sign that indicates your lawn is chemical-free.
  • Have community conversations about local seaweed habitats, MPAs, and local drivers of damage; seek to reduce harmful practices such as overuse of fertilizers and pesticides; educate friends and neighbors about local degraded seaweed habitats and potential solutions.
  • Consider donating or contributing to local protection efforts.
  • Try to purchase sustainable seaweed products that support local protection efforts.
  • When traveling, look for opportunities to support seaweed protection projects and ecotourism.
  • Advocate for strong land tenure rights; support Indigenous property rights and autonomy to protect watersheds and adjacent terrestrial systems to seaweed habitats.
  • Ensure projects operating in or with Indigenous communities only do so under FPIC; help codify FPIC into legal systems.
  • Help document and develop knowledge-sharing opportunities for Indigenous and local knowledge.
  • Help create educational and volunteer programs that work with schools, universities, NGOs, and the general public to inform communities of how to participate in seaweed protection efforts, benefits, and opportunities; develop local capacity in seaweed protection, especially in community-led monitoring and evaluation; establish knowledge-sharing initiatives with Indigenous peoples.
  • Join, create, or participate in public-private partnerships dedicated to mobilizing financing, protection activities, knowledge transfers, general education, and other relevant areas.
  • Join, support, or create certification schemes that verify protected areas and sustainable use of seaweed products.

Further information:

Sources
Evidence Base

Consensus of effectiveness at reducing emissions and maintaining carbon removal: Mixed

There is mixed scientific consensus that protection prevents the degradation of seaweed ecosystems, but high consensus that degradation leads to losses in biomass carbon stocks and sequestration capacity. Seaweed ecosystems can be degraded by diverse stressors that directly or indirectly affect biomass stocks. Management actions, such as establishment of MPAs, can help prevent both direct and indirect habitat loss and thereby maintain the carbon removal capacity of seaweed ecosystems with relatively high certainty against stressors such as wild harvesting, coastal development, overgrazing, and poor water quality (Pessarrodona et al., 2023). However, some stressors, such as marine heat waves and ocean warming, are less effectively addressed by protection alone (Filbee-Dexter et al., 2024a). Benefits are still expected in some systems because MPAs can enhance resilience and recovery by reducing co-occurring stressors common that contribute to seaweed ecosystem degradation (Krumhansl et al., 2016; Ortiz-Villa et al., 2025). Moreover, MPAs, even when established in areas with addressable stressors, are typically not fully effective. Here, we applied a protection effectiveness of 53%, based on aggregated estimates from MPAs beyond seaweed ecosystems (Rodríguez-Rodríguez & Martínez-Vega, 2022). If the effectiveness of protection is lower (higher), climate impacts could likewise be lower (higher).

There is high scientific consensus that degradation of seaweed ecosystems leads to losses in biomass carbon stocks and sequestration capacity. While direct estimates of CO₂ emissions from biomass are limited, degradation has been shown to remove biomass carbon and reduce sequestration. For instance, drivers of habitat loss and degradation, such as overharvesting (González-Roca et al., 2021; Steen et al., 2016), overgrazing (Akaike & Mizuta, 2024), and poor water quality (Filbee-Dexter & Wernberg, 2020), reduce standing biomass and therefore associated carbon export from seaweed ecosystems (Pessarrodona et al., 2023). 

The carbon sink capacity of seaweed ecosystems, such as kelp forests, is also expected to decline with climate change stressors such as warming, which can increase rates of decomposition by 9–42% (Filbee-Dexter et al., 2022) and drive habitat loss, both of which reduce the likelihood that carbon makes its way to the deep sea for long-term storage. Off the coast of Australia, over 140,000 ha of subtidal brown seaweed forests have already been lost to warming over two decades, representing a decline of 2–4% of regional seaweed biomass carbon stocks and sequestration capacity (Filbee-Dexter & Wernberg, 2020).

The results presented in this assessment synthesize findings from 5 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 on understudied aspects of these ecosystems.

Appendix

This analysis quantifies emissions that can be avoided by protecting seaweed ecosystems via the establishment of Marine Protected Areas (MPAs). We leveraged two global seaweed distribution maps alongside a shapefile of MPAs, available data on rates of avoided ecosystem loss attributable to MPA establishment, and global data on biomass carbon stores and carbon sequestration rates to calculate climate impacts. This appendix describes the source data products and how they were integrated.

Seaweed Ecosystem Extent

We relied on the global maps of seaweed extent developed by Duarte et al. (2022), which classify subtidal brown and red seaweeds (among others). We used the “LT2 Brown Algae Benthic” raster to calculate subtidal brown seaweed extent and the “LT2 Red Algae Benthic” raster to calculate subtidal red seaweed extent. We did not consider red seaweed in subtidal brown-dominant environments, such as kelp forests, due to existing limitations with the global maps. 

Protected Seaweed Ecosystem Areas

We identified protected seaweed ecosystem areas using the World Database on Protected Areas (UNEP-WCMC & IUCN, 2024), which contains boundaries for each MPA and additional information, including the establishment year and IUCN management category (Ia to VI, not applicable, not reported, or not assigned). In this analysis, we considered all categories. While some MPA categories likely allow for wild harvest, which can be unsustainably conducted, wild seaweed harvest is currently estimated at 1.3 Mt/yr (wet weight) (FAO, 2024), which represents a relatively small portion of the global loss rate used (<0.2%/yr). We converted the MPA boundary data to a raster and used them to calculate the seaweed area within MPA boundaries for each seaweed type analyzed (subtidal brown and red) and each MPA category. To evaluate trends in adoption over time, we also aggregated protected areas by establishment year as reported in the WDPA. 

Calculation of Effectiveness

The following equations show a detailed breakdown of the stepwise set of calculations used to implement Equation 1, including estimation of avoided seaweed loss and of emissions and retained sequestration across the 30-year time horizon considered.

Avoided Seaweed Ecosystem Conversion

We compiled baseline estimates of seaweed ecosystem loss (%/yr) from existing literature and used them in conjunction with an estimate of reductions in loss associated with protection of 53% (derived from Rodríguez-Rodríguez & Martínez-Vega, 2022) to calculate the rate of avoidable macroalgae loss (Seaweed lossavoided). Seaweed ecosystem loss rates were based on the original analysis of data aggregated from Krumhansl et al. (2016) for studies over 20 years long (Seaweed lossbaseline; median loss rate of 1.2%/yr). 

Equation A1.

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

We then used the avoidable seaweed loss rates to calculate avoided CO₂ emissions and additional carbon sequestration for each adoption unit. Specifically, we estimated the carbon benefits of avoided seaweed ecosystem loss by multiplying avoided seaweed ecosystem loss by avoided CO₂ emissions (Equation A2) and by applying carbon sequestration rates over 30 years (Equation A3) for each seaweed type. 

We estimated avoided CO₂ emissions by assuming a one-time release of all aboveground biomass carbon upon loss. We derived our estimates of retained carbon sequestration from global databases on NPP for each seaweed type from Duarte et al. (2022) and a global estimate of NPP-derived sequestration (11.4%) from NPP based on Krause-Jensen and Duarte (2016). 

Equation A2.

\[Avoided\ emissions= Seaweed\ loss_{avoided} \times \sum_{t=1}^{30}(Emissions)\]

Equation A3.

\[Sequestration= Seaweed\ loss_{avoided} \times \sum_{t=1}^{30}(Sequestration)\]

We then estimated effectiveness (Equation A4) as the avoided CO₂ emissions and retained carbon sequestration capacity attributable to the reduction in seaweed ecosystem loss conferred by protection estimated in Equations A1–3.

Equation A4.

\[Effectiveness = (Carbon_{avoided\ emissions}+ Carbon_{sequestration})\]
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