Precipitation trends determine future occurrences of compound hot\u2013dry events

Emanuele Bevacqua,Flavio Lehner,Jakob Zscheischler,Giuseppe Zappa

doi:10.1038/s41558-022-01309-5

Abstract

Compound hot–dry events—co-occurring hot and dry extremes—frequently cause damages to human and natural systems, often exceeding separate impacts from heatwaves and droughts. Strong increases in the occurrence of these events are projected with warming, but associated uncertainties remain large and poorly understood. Here, using climate model large ensembles, we show that mean precipitation trends exclusively modulate the future occurrence of compound hot–dry events over land. This occurs because local warming will be large enough that future droughts will always coincide with at least moderately hot extremes, even in a 2 °C warmer world. By contrast, precipitation trends are often weak and equivocal in sign, depending on the model, region and internal climate variability. Therefore, constraining regional precipitation trends will also constrain future compound hot–dry events. These results help to assess future frequencies of other compound extremes characterized by strongly different trends in the drivers.

Highlights

Compound hot–dry events—co-occurring hot and dry extremes—frequently cause damages to human and natural systems, often exceeding separate impacts from heatwaves and droughts
Previous studies have focused on assessing the frequency of compound hot–dry events, which is crucial for developing strategies to cope with the compound-event impacts
In this article, employing climate model output from an ensemble of seven single-model initial-condition large ensembles[16] (SMILEs), we address these research gaps; that is, we reveal the importance of mean precipitation trends for future frequency of compound hot–dry events (fHD), and investigate present and future uncertainties in fHD and their sources

Summary

Introduction

Compound hot–dry events—co-occurring hot and dry extremes—frequently cause damages to human and natural systems, often exceeding separate impacts from heatwaves and droughts. Trends in mean precipitation as key modulator In a warmer climate, the global average frequency of compound hot–dry events is projected to increase to a land average of about 12% (multimodel range: 10–14%), or about four times higher compared with 1950–1980 (Fig. 2a)[9].

Results

Conclusion