ABSTRACT

Soil carbon is the major active pool of terrestrial carbon, and as such, soil organic carbon (SOC) targets, policies and measures will be pivotal to achieving global climate targets. SOC sequestration may reduce the net annual greenhouse gas emissions from Agriculture, Forestry and Other Land Use by between 3% and 71%, while simultaneously supporting various ecosystem services. Accurate SOC accounting and monitoring, however, is constrained by various technical challenges related to indicators, rates of SOC change, measuring the impact of management practices on SOC, and the long-term persistence of sequestered SOC. We assessed countries’ pledges to the Paris Agreement for SOC in agriculture to better understand the level, transparency, and specificity of commitments. Reviewing 184 countries’ initial Nationally Determined Contributions (NDCs), we considered whether SOC was included, what was pledged, the level of ambition promised and the specificity of mitigation targets. Twenty-eight countries referred to SOC in their NDCs, citing quantified or unquantified mitigation targets, national policies or programs, and actions and measures to be implemented in agricultural lands (14), peatlands (6) or wetlands (14). Countries’ reasons for not including SOC in NDCs included the need to prioritize goals of sustainable development and food security above climate mitigation, a lack of incentives for farmers to improve management practices, and the difficulty of accurately monitoring changes in SOC. Including SOC targets in NDCs can improve NDCs’ comprehensiveness and transparency to track and compare policy progress across NDCs; it can also leverage SOC-related climate finance, technical support, and capacity building.

Key policy insights

1. Many NDCs specify practices known to have the potential to achieve SOC sequestration or protection without explicitly mentioning SOC. The SOC-related mitigation potential of these practices can be quantified in future NDCs.

2. NDCs are not presently a good indicator of countries’ interest or commitment to SOC action at national level. To improve this, countries with existing SOC policies, programs, and actions can specify their SOC-related commitments in future NDCs.

3. Increased collaboration between countries with experience managing SOC and countries needing support to develop SOC-related targets, policies, measures and incentives for land users and farmers would facilitate the provision of such needed support.

4. To increase country commitments and attention to managing SOC, there is a need for improved SOC measurement and monitoring, for better evidence on the impacts of management practices on SOC, and for incentives for farmers to change practices and overcome barriers.

摘要

土壤碳是陆地碳的主要活跃库，因此，土壤有机碳 (SOC) 目标、政策和措施对于实现全球气候目标至关重要。SOC 封存可将农业、林业和其他土地利用的年度温室气体净排放量减少 3% 至 71%，同时支持各种生态系统服务。然而，准确的 SOC 核算和监控受到与指标、SOC 变化率、衡量管理实践对 SOC 的影响以及隔离 SOC 的长期持续性相关的各种技术挑战的限制。我们评估了各国对农业 SOC 巴黎协定的承诺，以更好地了解承诺的水平、透明度和具体性。审查 184 个国家的初始国家自主贡献 (NDC)，我们考虑了 SOC 是否包括在内、承诺的内容、承诺的雄心水平以及缓解目标的具体性。28 个国家在其国家自主贡献中提到了 SOC，引用了量化或未量化的缓解目标、国家政策或计划，以及将在农业用地 (14)、泥炭地 (6) 或湿地 (14) 实施的行动和措施。各国不将 SOC 纳入 NDC 的原因包括需要将可持续发展和粮食安全目标置于缓解气候之上，缺乏对农民改进管理实践的激励，以及难以准确监测 SOC 的变化。将 SOC 目标纳入 NDC 可以提高 NDC 的全面性和透明度，以跟踪和比较 NDC 之间的政策进展；它还可以利用与 SOC 相关的气候融资、技术支持、

关键政策见解

1. 许多 NDC 指定了已知有可能实现 SOC 封存或保护的实践，而没有明确提及 SOC。这些实践的 SOC 相关缓解潜力可以在未来的 NDC 中量化。

2. NDC 目前并不是国家对 SOC 行动在国家层面的兴趣或承诺的良好指标。为了改善这一点，拥有现有 SOC 政策、计划和行动的国家可以在未来的 NDC 中明确其与 SOC 相关的承诺。

3. 具有管理 SOC 经验的国家与需要支持为土地使用者和农民制定与 SOC 相关的目标、政策、措施和激励措施的国家之间加强合作，将有助于提供此类所需的支持。

4. 为了增加国家对 SOC 管理的承诺和关注，需要改进 SOC 测量和监测，更好地证明管理实践对 SOC 的影响，并激励农民改变做法和克服障碍。