Increases in summertime concurrent drought and heatwave in Eastern China

Droughts and heatwaves can have profound impacts on society and the environment, which can be exacerbated by their co-occurrence. However, in China, co-occurrence of droughts and heatwaves has not been explored. Here we assess concurrent drought and heatwave events (CONDH) in summer across eastern China (EC) for 1962–2015. We found that these events are more frequent in the North and South of EC (>20 events during 1962–2015) and less frequent in the central region. In the North and South regions, intensity of heatwaves is ~2–4 times higher during drought conditions than in average conditions. Also, in these two regions the number of CONDH events is more than double what would be expected if droughts and heatwaves were independent. When analyzing changes between 1962–1988 and 1989–2015, the dependence between drought and heatwave was shown to be stable, but the number of CONDH more than doubled in parts of the North and small areas in the South, and decreased by over 50% in the southern central region. We have shown that the North and South of EC are hotspots of compound droughts and heatwaves and therefore it is crucial to considering both events together when assessing how to adapt to present and future weather extremes.