Whole-profile-warming drives carbon loss linked to soil carbon stock

Abstract Global warming may significantly reduce soil organic carbon (SOC) storage and stability, particularly in subsoil layers, where carbon loss mechanisms remain poorly understood. By synthesizing data from global whole-profile warming experiments, we demonstrate that CO 2 emissions from the whole-profile are 1.3 times stimulated. The extent of SOC loss is largely determined by standing SOC stocks, highlighting its vulnerability to climate warming. Significant SOC loss (26.4%) occurs in forests, but not in alpine grasslands and wetlands, highlighting ecosystem-dependent responses to warming. The relative losses of subsoil SOC stocks in forests exhibited a significant positive correlation with soil depth (Qm = 4.4, p = 0.0357), and warming leads to a greater proportional loss of SOC in the subsoil (30.6%) compared to the topsoil (14.5%). These depth-dependent responses can be attributed to the combination of biotic factors (e.g., higher microbial biomass but lower C use efficiency) and abiotic factors (e.g., reduced water content). The imbalance between reduced carbon input and increased decomposition rates drives SOC loss from the subsoil, which must be accounted for to make accurate predictions of SOC dynamics in a warming world. Graphical Abstract