Spatiotemporal changes in frequency and intensity of high-temperature events in China during 1961-2014

In this study, we explored spatial patterns and the temporal trends in high-temperature events (HTEs) for the mainland of China during 1961-2014 based on a daily- maximum surface-air-temperature dataset of 494 stations and nonparametric trend detection methods. With three thresholds of 35A degrees C (HTE35), 37A degrees C (HTE37), and 40A degrees C (HTE40), HTEs occurred in 82%, 71%, and 37% of the surveyed stations and showed an overall increasing trend in both frequency and intensity during 1961-2014. In northern and southeastern China, HTEs showed a significant increasing trend in both frequency and intensity, whilst a decreasing trend for both was observed in central China. Despite such regional heterogeneity, HTEs overwhelmingly presented three-phase characteristics in all three representative regions and throughout China; the phases are 1961-1980, 1980-1990, and 1990-2014. Both frequency and intensity of HTEs have strongly increased during 1990-2014 at 54.86%, 48.38%, and 23.28% of the investigated stations for HTE35, HTE37 and HTE40, respectively. These findings implied that HTEs adaptation should be paid further attention in the future over China because the wide spread distribution of HTEs and their increasing trends in both frequency and intensity during recent decades might pose challenges to the sustainability of human society and the ecosystem.