Future changes in the frequency of temperature extremes may be underestimated in tropical and subtropical regions

This is the final version. Available from Nature Research via the DOI in this record. The authors declare that all data that support the findings in the main article are available. All model data are publicly accessible via the Earth System Grid Federation node (https://esgf-node.ipsl.upmc.fr/). ERA5 data can be downloaded from ECMWF website (https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5). CHIRTS data can be downloaded from https://www.chc.ucsb.edu/data/chirtsdaily.In a warming world, temperature extremes are expected to show a distinguishable change over much of the globe even at 1.5 °C warming, and in many regions this change has already been detected in observations. Although many studies predict an increase in heat extreme events, the magnitude of the change varies greatly among different models even for the same mean warming. This uncertainty has been linked to differences in land–atmosphere feedback across models. Here we show that a significant constraint for future projections can be based on the ability of climate models to accurately simulate the present day variability of daily surface maximum temperature. An emergent constraint on Coupled Model Intercomparison Project Phase 5 (CMIP5) and 6 (CMIP6) models, applied to ERA5 reanalysis, indicates that the best estimate in hot extreme changes by the end of the century could be worse than previously estimated, mostly for tropical and subtropical regions as well as South and East Asia.Natural Environment Research Council (NERC