Evidence of anthropogenic impacts on global drought frequency, duration, and intensity

Felicia Chiang,Amir Aghakouchak,Omid Mazdiyasni

doi:10.1038/s41467-021-22314-w

Felicia Chiang, Amir Aghakouchak + Show 1 more

Open Access

https://doi.org/10.1038/s41467-021-22314-w

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Abstract

Most climate change detection and attribution studies have focused on mean or extreme temperature or precipitation, neglecting to explore long-term changes in drought characteristics. Here we provide evidence that anthropogenic forcing has impacted interrelated meteorological drought characteristics. Using SPI and SPEI indices generated from an ensemble of 9 CMIP6 models (using 3 realizations per model), we show that the presence of anthropogenic forcing has increased the drought frequency, maximum drought duration, and maximum drought intensity experienced in large parts of the Americas, Africa, and Asia. Using individual greenhouse gas and anthropogenic aerosol forcings, we also highlight that regional balances between the two major forcings have contributed to the drying patterns detected in our results. Overall, we provide a comprehensive characterization of the influence of anthropogenic forcing on drought characteristics, providing important perspectives on the role of forcings in driving changes in drought events.

Highlights

Most climate change detection and attribution studies have focused on mean or extreme temperature or precipitation, neglecting to explore long-term changes in drought characteristics
Using standardized precipitation indices (SPI) and standardized precipitation-evapotranspiration index (SPEI) indices generated from an ensemble of 9 Coupled Model Intercomparison Project Phase 6 (CMIP6) models, we show that the presence of anthropogenic forcing has increased the drought frequency, maximum drought duration, and maximum drought intensity experienced in large parts of the Americas, Africa, and Asia
In addition to our SPI-based analysis, we examined drought characteristics based on standardized precipitation-evapotranspiration index (SPEI) data to better understand anthropogenic forcing impacts on net water availability, regarded here as the difference between monthly precipitation and potential evapotranspiration[30]

Summary

Introduction

Most climate change detection and attribution studies have focused on mean or extreme temperature or precipitation, neglecting to explore long-term changes in drought characteristics. Since future climate projections suggest increases in drought frequency and severity in the Americas, Europe, Asia, and Africa, the characterization of drought features is an important and relevant area of study in the field of hydrology[12,13,14,15,16,17]. Previous detection and attribution studies have used observations and model simulations to attribute increasing trends of mean and extreme temperature and precipitation occurrences to anthropogenic emissions[18,19,20,21,22,23]. There have been many detection and attribution studies on hydroclimatic variables in the literature[18,19,22,24,25,26], the global influence of anthropogenic forcing on different drought characteristics (e.g., duration, frequency, severity) has not been explicitly quantified.

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