Attribution of observed changes in extreme temperatures to anthropogenic forcing using CMIP6 models

Global warming has clearly affected the occurrence of extreme events in recent years. Here, we assess changes frequency temperature extremes and their causes, using percentile-based indices. Cold are defined as temperatures below 10th percentile daily minimum (TN10) maximum (TX10) while hot exceed 90th (TN90) (TX90) temperatures. We analyze Berkeley Earth Surface Temperature (BEST) for observed last four decades 1981-2020, two extended seasons, boreal summer April–September (AMJJAS) winter October–March (ONDJFM), evaluate results several reanalysis data sets. For attribution causes use CMIP6 climate model simulations, analyzing natural-only anthropogenic-only forcings. an method that accounts modeling uncertainty both amplitude pattern responses. The observations show detectable cold Hot have increased all regions seasons decreased over past decades. Our analysis revealed anthropogenic forcings robustly main drivers indices regions, consistently Contributions from natural found small only a few mainly daytime ONDJFM. Anthropogenic forcing contributed to increase 3.4 days per decade TN90 2.7 TX90, on average, at global scale. Regionally, contribution caused range decrease 2–4.7 TN10, 1.5–3.6 TX10 it 2.2–4.8 2–3.3 TX90. Anthropogenic-only ONDJFM is slightly less than AMJJAS.