Warming could cause significant soil organic carbon loss around the southern Baltic Sea

Soil organic carbon (SOC) is linked to greenhouse gas emissions and climate change. Loss of SOC is one of the main threats to European and global soils. The impact of climate change, especially warming, on SOC varies by regions but remains poorly understood. To address this, we used Random Forest (RF) to model SOC in topsoil of Europe based on LUCAS data and applied SHapley Additive exPlanations (SHAP) values to interpret spatial patterns. Key findings show temperature is the predominant factor influencing SOC in northern Europe (north of 55°N). Under the RCP4.5 scenario, projected warming over the next 50 years could lead to significant SOC loss around the southern Baltic Sea (55°N-60°N), while regions north of 65°N could experience SOC gain. Regions between 60°N-65°N would have mixed SOC changes or remain stable. The southern Baltic Sea region, with annual mean temperature of 2.5-7.5 °C, is identified as highly sensitive to SOC loss due to warming. These findings have improved our understanding of the spatially varying SOC-temperature relationships and highlighted the need to consider regional SOC dynamics in future soil management and climate-related policies. In addition, agro-environmental actions at the regional scale should be adopted to enhance SOC conservation.