Half of the soil organic carbon stabilization potential remains untapped for climate change mitigation

Stabilized soil organic carbon (SSOC) represents the most persistent pool of soil carbon (C) and is crucial for long-term climate mitigation and adaptation, yet its global distribution and drivers remain poorly understood. By integrating georeferenced soil observations with a high-precision XGBoost model, this report provides the first global assessment of SSOC stocks and their controlling factors in the surface one-meter layer. The global SSOC stock is estimated at 1300 Pg C, accounting for roughly half of total soil organic carbon (SOC). Wetlands store the largest SSOC pools (Mg ha-1), followed by forests, grasslands, and croplands, with the highest content in cold-temperate regions. Soil properties (i.e., SOC, pH, bulk density) dominate SSOC moderation (77−92%), surpassing climatic and anthropogenic influences. This report also introduces the concept of soil negative carbon potential (SNCP), the proportion of SSOC within total SOC, as a new indicator of soil C stabilization. Raising SNCP strongly reduces greenhouse gas emissions and increases economic growth with minimal yield trade-offs. The findings reported herein provide a benchmark for Earth system models, highlight the untapped potential of soil C stabilization, and call for policy frameworks that integrate soil management into global C neutrality strategies.