As climate change intensifies, the frequency of extreme weather events—such as heatwaves and droughts—is on the rise. Flash droughts, which are characterized by their rapid onset and severe impacts, are becoming increasingly common in the 21st century. Notable examples include the 2012 flash drought in the U.S. Midwest and the 2022 drought along the Yangtze River, both of which resulted in significant reductions in terrestrial carbon sinks and crop yields. Understanding ecosystem resilience to flash droughts is essential for developing effective adaptation strategies. However, global-scale, long-term studies on vegetation resistance to these events remain limited.

To address this challenge, a research team led by Prof. YUAN Xing from the Institute of Atmospheric Physics of the Chinese Academy of Sciences, in collaboration with researchers from Nanjing University of Information Science and Technology, has introduced a flash drought resistance index. They utilized multi-source remote sensing vegetation data, hydro-meteorological reanalysis datasets, and machine learning techniques to evaluate vegetation resistance to flash droughts from 2001 to 2022. This study was published in Nature Communications.

The findings indicate a substantial decline of 27% (±5%) in vegetation resistance across key regions, including East Asia, western North America, and northern Europe. This trend is largely driven by worsening atmospheric drought conditions, rising temperatures, and increased vegetation sensitivity to drought stress. Unlike slowly developing droughts, flash droughts pose a greater risk to ecosystems, leading to more rapid declines in productivity and shorter response times.

"Our results highlight the increasing vulnerability of global ecosystems to flash droughts," said Prof. YUAN. "Understanding these trends is vital for assessing ecological risks and informing future adaptation strategies."

This study offers new insights into how climate change is affecting vegetation resilience and emphasizes the need for proactive measures to mitigate the impacts of flash droughts.

The linear trends of 5-point running average resistance to flash droughts over the 27 IPCC SREX regions. (Image by Prof. YUAN's group)