Synergistic interactions between warming and elevated atmospheric CO2 increase soil organic carbon sequestration

Warming and elevated CO2 (eCO2) are two potentially opposing climate-carbon (C) feedback mechanisms that modulate the magnitude of the land C sink, with warming decreasing and eCO2 increasing C sequestration. However, their net effect on soil organic C (SOC)—the largest terrestrial C stock—remains uncertain. Here, we quantify how warming, eCO2, and their interactions influence SOC by using 5,558 paired observations from 1,392 global studies across ecosystem types.