Regional Disparity in Impacts of Compound Heat and Drought Extremes on Population and Major Crops Across China

Abstract

Under global warming, compound heat and drought days (CHDDs) pose significant threats to both human health and agricultural production. This study systematically investigated CHDDs and the population and major crops exposed to the events across China from 1961 to 2022, using daily-scale temperature and standardized precipitation evapotranspiration index (SPEI). By integrating conventional percentile thresholds and crop-specific physiological stress temperatures for major crops, we employed a 3D visualization framework to quantify the co-occurrence patterns of extreme heat, drought, and CHDDs. The analysis revealed significant decadal changes: a sudden increase in CHDDs was observed in the late 1990s in eastern regions, while western China has shown a consistent upward trend since the 1980s. The highest exposure levels were concentrated in eastern China, where dense populations and extensive crop cultivation have driven a significant rise in both population and crop exposure since the 1990s, particularly for maize and rice. Pronounced regional disparities were evident in the characteristics of CHDDs: while drought days were more frequent in the northwest, southeastern China experienced the highest frequency and fastest growth rate of CHDDs. As a result, southeastern China has experienced the most significant increases in population exposure and the exposure of maize and rice crops. Meanwhile, the northwest arid region has seen rapid growth in population exposure and the exposure of maize and wheat crops, while Northeast China has shown a notable rise in maize exposure. These findings highlight the need for region-specific adaptation strategies to protect China’s food security and public health in a warming climate.

Keywords

China / Compound heat and drought days / Exposure / Major crops / Population / Regional disparity

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