Changes of concurrent drought and heat extremes in the arid and semi-arid regions of China during 1961–2014

Abstract

Arid and semi-arid regions of China (ASRC) are increasingly threatened by drought. Especially when drought and heat extremes coincide, the resultant impact would be even more harmful to human society and the natural environment. This study investigates the spatio-temporal changes in concurrent drought and heat extremes in ASRC during 1961–2014. Summer heat extremes quantified by hot day (HD), warm night (WN), daytime (DHW), and nighttime heatwave (NHW) are examined. On average, the concurrent nighttime events (concurrent drought-WN and drought-NHW) increases by 2.7 times faster than daytime ones (concurrent drought-HD and drought-DHW), and they appear more frequently in eastern than western ASRC. We also find that all four types of concurrent events have been significantly increased over the past decades. Compared to daytime (i.e., HD and DHW), the concurrent events at nighttime (i.e., WN and NHW) increased even more rapidly. During the study period, concurrent drought-DHW (drought-NHW) climbed up at the rate of 0.03 (0.08) events decade−1 and concurrent drought-HD (drought-WN) increased by 0.17 (0.45) days decade−1. Geographically, eastern ASRC exhibited a more pronounced increasing trend than the west. Given the increasing threats of concurrent events, we suggest that more attention should be paid to these compound events in future climate change studies.