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

N Freychet,D Mitchell,M Collins,G Hegerl

doi:10.1038/s43247-021-00094-x

Abstract

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.

Highlights

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
There is evidence that many current climate models are too dry under the present conditions[15] and we hypothesize that this amplifies TX variability and with it, heat wave frequency[16], whereas more accurate models may see this amplification in upcoming decades
It is verified that models with the largest change in TX98p have stronger decreases in latent heat flux (Supplementary Fig. 1c) over tropical/subtropical areas and South and East Asia, i.e., they are drying more compared to other models between the present time and the end of the century

Summary

Introduction

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. Heat flux is overall negative where the EC is significant and has the strongest influence on results (Supplementary Fig. 1), indicating larger temperature variability for weaker fluxes (drier soils), supporting our hypothesis.

Results

Conclusion