Grassland Protection
Grasslands hold large stocks of carbon, largely underground. Protecting them shields this carbon and avoids emissions from conversion to agriculture or development.
Reduced/Sequestered
2020–2050
Impact
Increasing protection of intact grasslands to 369.31–403.18 million hectares could avoid greenhouse gas emissions totaling 3.35–4.25 gigatons by 2050, securing an estimated protected stock of 34–37 gigatons of carbon, roughly equivalent to more than 124–136 gigatons of carbon dioxide if released into the atmosphere. We don’t project financials because they are not incurred at the landholder level.
Introduction
Grasslands, including rangeland, shrubland, and savanna, store vast amounts of carbon. Grasslands also protect biodiversity and provide essential ecosystem services.
Project Drawdown’s Grassland Protection solution involves the legal protection of natural, ungrazed grasslands from future grazing and/or conversion to croplands. Protection reduces land use change and safeguards carbon sinks. We assumed that grassland protection primarily happens at the government and nongovernmental organization (NGO) level. This solution replaces unprotected grassland.
Grasslands are often converted to agriculture and are at high risk of future land use change and greenhouse gas emissions from loss of carbon stocks. Grasslands are also targeted for afforestation.
Methodology
Total Land Area
To evaluate the extent to which a Food, Agriculture, and Land Use sector solution can reduce greenhouse gas emissions and sequester carbon, we need to identify the total land area available for that solution in millions of hectares. To avoid double counting, we use an integration model that allocates land area among all Food, Agriculture, and Land Use sector solutions. This involves two steps. First, we classify the global land area into agro-ecological zones (AEZs) based on the land cover, soil quality, and slope and assign AEZs to different thermal moisture regimes. We then classify the AEZs into “degraded” and “nondegraded.” Finally, we allocate the solutions to AEZs, with the solution most suited to a given AEZ or sets of AEZs assigned first, followed by the second-most-suited solution, and so on. Because it’s hard to predict future changes, we assume the total land area remains constant.
We set the total area of nondegraded grasslands available for protection at 500 million hectares. Current adoption (defined as the amount of functional demand supplied in 2018) was 159 million hectares.
Adoption Scenarios
We developed four custom adoption scenarios based on protection commitments made for temperate grassland and on global grassland protection data from 1996 and 2009 (Henwood, 1998; Henwood, 2010).
We calculated impacts of increased adoption of grassland protection from 2020 to 2050 by comparing two growth scenarios with a reference scenario in which the market share was fixed at current levels.
- Scenario 1: 369.31 million hectares of nondegraded forest are protected by 2050 (74 percent of the total land area).
- Scenario 2: 403.18 million hectares of nondegraded forest are protected by 2050 (81 percent of the total land area).
Emissions Model
We set one-time emissions from deforestation to 64.272 metric tons of carbon dioxide equivalent per hectare, based on meta-analysis of 13 data points from seven sources. We set sequestration to 0.03 based on three data points from three sources.
Financial Model
We assume that any costs for grassland protection (e.g., carbon payments or payment for ecosystem services) are borne at a government or nongovernmental organization (NGO) level. Project Drawdown Food, Agriculture, and Land Use sector solutions only model costs that are incurred at the landowner or manager level.
Integration
Project Drawdown’s Agro-Ecological Zone model allocates adoption of solutions to forest, grassland, rain-fed cropland, and irrigated cropland. The Grassland Protection solution was the first priority solution for use of nondegraded grassland, followed by the Multistrata Agroforestry, Perennial Staple Crops, Silvopasture, and Managed Grazing solutions.
Results
Scenario 1 averts 3.35 gigatons of carbon dioxide equivalent emissions by 2050. Total carbon stock protected is 124.9 gigatons of carbon dioxide equivalent.
Scenario 2 averts 4.25 gigatons of carbon dioxide equivalent by 2050. Total carbon stock protected is 136.3 gigatons of carbon dioxide equivalent.
Discussion
Benchmarks
The International Panel on Climate Change (IPCC) Climate Change and Land report (IPCC 2019) notes a range of 0.03–0.72 gigatons of carbon dioxide equivalent per year from reduced conversion of cropland to grassland. Griscom (2017) estimates 0.1 gigatons of carbon dioxide equivalent per year from avoided cropland conversion, assuming a 30 percent reduction. Our estimates of 0.1–0.16 gigatons per year in 2030, are in line with these benchmarks.
Limitations
This solution does not model avoided deforestation from agricultural intensification or reduced food demand due to diet change or food waste reduction. It would be valuable to include economic impacts (e.g., costs to governments and NGOs) in future updates.
Conclusions
Grasslands preserve important global carbon stocks and provide important ecosystem services. They are highly at risk of conversion to grazing, cropland, and biomass/bioenergy crops. Protection of grassland is an important strategy to limit emissions from land use change.
References
Griscom, B. W., Adams, J., Ellis, P. W., Houghton, R. A., Lomax, G., Miteva, D. A., ... & Fargione, J. (2017). Natural climate solutions. Proceedings of the National Academy of Sciences, 114(44), 11645-11650.
Henwood, W. D. (1998). An overview of protected areas in the temperate grasslands biome. Parks, 8(3), 3-8.
Henwood, W. D. (2010). Toward a strategy for the conservation and protection of the world's temperate grasslands. Great Plains Research, 121-134.
IPCC, 2019: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management,food security,andgreenhousegasfluxe interrestrial ecosystems [P.R.Shukla, J.Skea, E.CalvoBuendia, 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.)]. In press.
