Variations in start date, end date, frequency and intensity of yearly temperature extremes across China during the period 1961-2017

Abstract

Frequent temperature extremes due to climate change have had serious effects on human society and the natural environment. Using a 0.25 degrees x 0.25 degrees gridded Tmax (daily maximum temperature) and Tmin (daily minimum temperature) data set and 12 global climate models simulations from the sixth phase of the Coupled Model Intercomparison Project (CMIP6), we investigated variations in yearly temperature extremes in China during the past five decades with respect to four characteristics, namely, their start date, end date, frequency, and intensity. Results showed that the occurrence of nighttime extremes (the cold nights and warm nights) responded strongly to climate change. For 1961-2017, cold extremes started later (3.25 d/decade) and ended earlier (-4.58 d/decade), with decreased frequency (-6.56 d/decade), especially for cold nights, and weakened intensity (0.14 degrees C/decade). In the same period, warm extremes started earlier (-3.43 d/decade) and ended later (3.15 d/decade) with increased frequency (6.79 d/decade), especially for warm nights, and enhanced intensity (0.09 degrees C/decade). The spatial pattern of the variations was complex with anomalous regions. Multimodel ensembles (MMEs) from CMIP6 agreed well with observations regarding the average trends of temperature extremes over China, although detailed changes in spatial pattern were not captured adequately. The hazards of temperature extremes deserve close attention in the future due to the complex changes likely to occur across China for various characteristics of these temperature extremes under conditions of climate change.