Stability of China's terrestrial ecosystems carbon sink during 2000-2020

Abstract

China's terrestrial ecosystem carbon sink (TCS) is crucial for the global carbon budget. However, little is known how the enhanced human disturbances and increased extreme climate events may potentially destabilize TCS under warming climate. Using three process-based ecosystem models, we simulated the spatiotemporal variations of China's terrestrial net ecosystem productivity (NEP) from 2000 to 2020. We found that 26.7 % of the land area exhibit simultaneous increases in NEP temporal variability and autocorrelation during this period, indicating an increasing risk of TCS destabilization. Particularly, the southeastern subtropical monsoon region in China emerged as a hot-spot of potentially increasing NEP instability, despite its high carbon sink capacity, both NEP temporal variability and autocorrelation in this area exhibit a notable upward trend. Climate change, notably increasing precipitation and its temporal variation, appeared to be the primary driver of this instability. This harbinger implies that a regime shift in carbon sink capacity may occur as the warming climate continues to push it to the verge of stability.