Future changes in compound drought events and associated population and GDP exposure in China based on CMIP6

Compound drought events, in which several types of drought occur at the same time, usually causes more harm to human society than just one type of drought event on its own. In this study, skill scoring methods are used to evaluate models, and then several drought indices are calculated to characterize meteorological, agricultural, and hydrological droughts, separately. Finally, the projected future changes in compound drought events, and associated population and GDP exposure to them, are further studied based on CMIP6. The results show that the frequency of compound drought events is likely to increase in northern Northwest China, Southwest China, and South China, but decrease in North and Northeast China. The projected changes in duration and severity are similar to those of frequency, i.e., mainly increasing in a few parts of northern Northwest and South China, but decreasing in Northeast and North China. The population exposure to compound drought events is expected to increase greatly in the area south of the Yangtze River Basin, slightly in Northwest China, and decrease greatly in the northeast of the Yangtze River Basin. Both climate and population have important effects on the change in population exposure. Due to the expected rapid growth in GDP, the exposure of GDP to compound drought events in almost all regions of China is projected to increase in the future, especially in eastern China, and the relative contribution of the GDP effect to the change in GDP exposure will be the largest.