Abstract
Two questions motivated this study: (a) Are global land regions exposed to future changes in absolute temperature extremes? (b) And to which degree? To answer these questions, we projected the trend in four indices, recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI), through the 21st century. Observational (HadEX3) and reanalyses (ERA5, JRA-55, NCEP-R-1, and NCEP-R-2) datasets were used to validate and correct the bias in the Coupled Model Intercomparison Project phase 6 (CMIP6) models. CMIP6 models were then used to evaluate the changes globally and in 44 reference regions under two shared socioeconomic pathways (SSPs): SSP2-4.5 and SSP5-8.5. Globally, the analysis showed that, under SSP5-8.5, TXx and TNx would increase by 0.07 degrees C/year, and TXn (TNn) would increase by 0.09 (0.08)degrees C/year, during the middle of the 21st century (2021-2050), compared with the reference period (1981-2010). These trends are larger during the end of the 21st century (2071-2100). The analysis also showed that all land reference regions are projected to indices growth up to 3.5 degrees C in TXx; 2.8 degrees C in TNx; 4.5 degrees C in TXn; and 4 degrees C in TNn, during the mid-21st century under SSP5-8.5. The latter growth in indices increased by 211% for TXx, 237% for TNx, 242% for TXn, and 300% for TNn during the end-21st century. The global hotspots affected by absolute temperature extremes are in the Northern Hemisphere, including North America, Iceland, Central Asia, Tibetan Plateau, Russian Arctic, Siberia, Mediterranean, Sahara, and Arabian Peninsula. The study's findings help understand the evolution of climate extremes, which is essential for climate change mitigation and adaptation plans.