Vegetation Greening and Climate Warming Increased the Propagation Risk From Meteorological Drought to Soil Drought at Subseasonal Timescales

• Published in: Geophysical research letters Vol. 51; no. 4
• Main Authors: Ma, Feng, Yuan, Xing
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28-02-2024; Wiley
• Subjects: Bayesian analysis; Changing environments; Climate; Climate and vegetation; Climate change; climate warming; Conditional probability; Divers; driver; Drought; drought propagation; Environmental changes; Environmental risk; Global warming; Greening; Heat waves; Heatwaves; Plant cover; Probability theory; Propagation; Risk; Soil; Soils; Spatial variations; subseasonal drought; Trends; Vapor pressure; Vapour pressure; Vegetation; Vegetation cover; vegetation greening; Watersheds; Wildfires
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL107937

Subseasonal droughts including flash droughts have occurred frequently in recent years, which are accompanied by heatwaves or wildfires that raise a wide concern on environmental risk. However, the changing characteristics of subseasonal drought propagation, and the possible climate and environmental drivers remain unknown. This study quantifies the propagation characteristics from meteorological drought to soil drought using a Copula‐based Bayesian framework, and shows that higher propagation risks mainly occur in more humid regions with denser vegetation cover. Trends in drought propagation risk vary regionally, with a global increase of 2%/decade (p < 0.01) during 1980–2022. Vegetation greening and climate warming are the key drivers over >71% of the global vegetated lands, with mean contribution rates of 39.5% and 36.5% respectively. Other climatic factors including vapor pressure deficit and precipitation also paly critical roles, which closely correlate with temperature and vegetation. These findings highlight the importance of vegetation greening on subseasonal drought propagation dynamics.
Plain Language Summary
Changing characteristics of seasonal‐interannual drought propagation have been well studied at watershed scales, and they were found to be principally ruled by climate divers and moderately affected by vegetation factors. In a changing environment, subseasonal droughts have occurred frequently worldwide, showing different characteristics and environmental responses with long‐term droughts. However, how climate and environment factors affect the subseasonal drought propagation characteristics remains unknown. This study investigates the propagation risk from meteorological drought to soil drought at subseasonal timescales based on a conditional probability method. We found that higher subseasonal drought propagation risks were mainly located in more humid vegetated regions, and the propagation risk showed an overall increasing trend (p < 0.01) from a global perspective but with significant spatial variations during 1980–2022. Climatic and vegetation factors jointly affect the trends in subseasonal drought propagation risks. Among them, vegetation greening and climate warming were the most important drivers over >71% of global vegetated regions.
Key Points
Higher propagation risk from subseasonal meteorological to soil drought mainly occurred in humid regions with denser vegetation cover
Trends in subseasonal drought propagation risk varied regionally, with a global mean increase of 2%/decade during 1980–2022
Greening and warming were the key drivers of the trends, with global mean contribution rates of 39.5% and 36.5% respectively