Generated Summary
This document is a technical report that explores the challenges and opportunities associated with carbon sequestration in grassland systems. The report examines the role of grassland management and climate change mitigation. It delves into the current state of opportunities and challenges, identifies components for future climate agreements, and aims to assist policy-makers in developing plans to improve grassland management. The report addresses key areas such as carbon sequestration, its impact on productivity, adaptation to climate change, and the economic potential of related practices. It also considers the challenges in implementing workable policies and incentives, especially regarding issues like additionality, reversals, and stakeholder engagement. The document emphasizes the importance of sustainable grassland management practices, research priorities, and their broader context within the scope of food security and climate change.
Key Findings & Statistics
- Grasslands, including rangelands, shrublands, pastureland, and cropland sown with pasture and fodder crops, covered approximately 3.5 billion ha in 2000. This represents 26 percent of the world land area and 70 percent of the world agricultural area.
- Grasslands contain about 20 percent of the world’s soil carbon stocks.
- Around 20 percent of the world’s native grasslands have been converted to cultivated crops.
- Significant portions of world milk (27 percent) and beef (23 percent) production occur on grasslands managed solely for those purposes.
- The livestock industry provides livelihoods for about 1 billion of the world’s poorest people and one-third of global protein intake.
- About 7.5 percent of the world’s grasslands have been degraded by overgrazing.
- Cultivation of native grasslands has contributed substantially to the transfer of about 0.8 Mg of soil carbon to the atmosphere annually.
- Globally, an estimated 0.2-0.8 Gt CO₂ yr⁻¹ could be sequestered in grassland soils by 2030, given prices for CO₂ of USD20–50/tonne.
- Grasslands contain a substantial amount of the world’s soil organic carbon – about 343 billion tonnes of C – nearly 50 percent more than is stored in forests worldwide.
- When grasslands are converted to agricultural land, soil carbon stocks tend to decline by an average of about 60 percent.
- Improved grazing management leads to an increase of soil carbon stocks by an average of 0.35 Mg C ha⁻¹ yr⁻¹.
- Agroforestry enhancements could sequester 0.012 Tg C yr⁻¹ while conversion of 630 million ha of unproductive or degraded croplands and grasslands to agroforestry could sequester as much as 0.59 Tg C annually by 2040.
- The technical potential for reduction of CH₄ emissions from manure to be 12.3 Tg C yr⁻¹ by 2030.
Other Important Findings
- Practices that sequester carbon in grasslands can enhance productivity.
- Practices that sequester carbon in grasslands can enhance adaptation to climate change.
- The potential income for practices that sequester carbon could lead to near-term dividends.
- Developing workable policies and incentives is difficult.
- Demonstrating additionality is a formidable challenge.
- Carbon sequestered in grassland systems is subject to reversals.
- Well-intentioned policies do not necessarily lead to good practices.
- Land tenure and governance issues complicate policy implementation.
- Systems for documenting carbon stock changes have not been agreed upon.
- Practice-based estimates of soil carbon sequestration can lead to uncertainty.
- Combining measurement with mechanistic modeling offers benefits.
- Data on management impacts on carbon stocks are limited in developing countries.
- Much of the world’s grassland, and a majority of grassland sequestration potential, is found in the developing world.
Limitations Noted in the Document
- The ability to measure changes in carbon stocks can be difficult, and benefits may be distributed across more landowners/land managers with less certain tenure.
- Sequestration rates can be slower than other methods.
- Costs of implementation are more poorly quantified, and the scientific information to inform policy analysis is less complete.
- Demonstrating additionality requires information other than sampling of biomass or soil carbon stocks.
- Documenting changes in biomass or soil carbon stocks will require some kind of measurement coupled with extrapolation or interpolation.
- The difficulty lies not in measuring carbon stocks but in devising measurement/monitoring/verification systems that are accurate yet cost-effective.
- Estimated rates of carbon sequestration per unit are lower than those for sequestration on agricultural land.
- The balance between inputs in another place by forage or feed harvest, has not been well characterized.
- Practice-based estimates of soil carbon sequestration are so sparse that to rely on them for sequestration rates for a specific farm or group of farms in a given region (which are unlikely to be well represented by published studies) will lead to substantial uncertainty.
- The lack of direct observations in the developing world makes estimates highly uncertain
Conclusion
The report underscores the critical role of grasslands in global carbon sequestration and climate change mitigation, emphasizing the potential for improved management practices to enhance both environmental and economic outcomes. The document highlights the substantial carbon storage capacity of grasslands and the benefits of practices that increase carbon uptake, reduce emissions, and enhance adaptation to climate change. Key findings suggest that practices to sequester carbon often enhance productivity, potentially leading to increased forage production and producer incomes. The report calls for the development of policies and programs that support sustainable grassland management, taking into account local environmental conditions, institutional capacities, and the needs of stakeholders, particularly smallholders and pastoralists. The challenges in implementing these practices are significant, including the complexity of demonstrating additionality, addressing the issue of impermanence, and the need for improved monitoring and verification systems. The report concludes that understanding and accounting for carbon and nitrogen flows will be instrumental in capitalizing on the full potential of grassland systems for adaptation and mitigation. The recommendations prioritize investments in sustainable land management practices that enhance productivity, mitigate greenhouse gas emissions, and enable adaptation to climate change. The success of these efforts hinges on collaborative approaches that involve scientists, grassland managers, and development actors, along with a commitment to the long-term stewardship of natural resources.