The rapidly evolving drought events, which are recently termed as “flash droughts” have occurred frequently around the world. Compared to traditional droughts, flash droughts are often triggered by extreme heat, accompanied by low soil moisture and high evapotranspiration (ET), with devastating impacts on crop yields and water supply. 

A research team consisting of WANG Linying, YUAN Xing, and XIE Zhenghui from Institute of Atmospheric Physics, Chinese Academy of Sciences, Peili Wu from UK Met Office and Yaohui Li from Institute of Arid Meteorology at China Meteorological Administration (CMA) used daily surface air temperature and precipitation observations from 2474 CMA meteorological stations to investigate the long-term trend and variability of flash droughts over China.  

The team found that flash droughts are most likely to occur over humid and semi-humid regions, such as southern and northeastern China. Flash drought averaged over China increased by 109% from 1979 to 2010, and the increase was mainly due to a long term warming of temperature (50%), followed by the contributions from decreasing soil moisture and increasing ET. The increasing trend of flash droughts was tripled, although there was a slight drop in temperature after 1997/98 big El Niño event.

Further results indicate that the decreasing temperature during the warming hiatus was compensated by the accelerated drying trends of soil moisture and enhanced ET, leading to an acceleration of flash droughts during the warming hiatus.

The changes of flash droughts are closely associated with global warming, and the anthropogenic warming in the next few decades may exacerbate future flash drought conditions in China. 

Interannual variations of ensemble mean flash drought event and its component variables averaged over China. (Image by Yuan et al., 2016) 

This study was published at Scientific Reports. It has been highlighted by the Earth and Environment Gateway of the Nature Asia (http://www.natureasia.com/zh-cn/earth-env/research/10894), and reported by the GuangMing Daily and Caixin Online.