Serious underestimation of reduced carbon uptake due to vegetation compound droughts

Compound droughts, characterized by low soil moisture (SM) and high vapor pressure deficit (VPD), severely threaten terrestrial carbon sinks. This study defines and identifies vegetation compound droughts (VCDs) where low SM and high VPD negatively impact vegetation carbon uptake. The research reveals frequent and severe VCDs, particularly in drylands, significantly underestimating the impacts of these events compared to quantile-based approaches. The frequency and intensity of VCDs are projected to increase, regardless of CO₂ fertilization effects. These findings highlight the underestimated risks of VCDs and underscore the need for adaptation measures.

Jiaxi Song, Sha Zhou, Bofu Yu, Yan Li, Yanxu Liu, Ying Yao, Shuai Wang, Bojie Fu