Warming Amplifies Responses of Soil Organic Carbon to Multiple Global Change Drivers.

Soil organic carbon (SOC) is the largest terrestrial C reservoir on Earth, which plays a critical role in climate regulation. While global warming is a defining feature of anthropogenic climate change, its interactive effects with other global change drivers on the content of SOC remain unclear. For this study we conducted a global meta-analysis of 2349 observations from 363 studies, which revealed that warming alone reduced SOC by 7.2% while synergistically amplifying responses to other drivers. It enhanced the effects of elevated CO2 by 240% and those of nitrogen addition by 350%, while exacerbating drought-induced losses by 340%. Noticeably, while warming revealed synergistic interactions with other drivers, the interactions between elevated CO2, nitrogen addition, and drought were additive. The responses of SOC consistently strengthened with treatment intensity and duration across diverse ranges of ecosystems, climates, and soil textures. These findings establish warming as a catalytic force that reshapes SOC dynamics under ongoing global change, with profound implications for terrestrial C-climate feedbacks.