Assessment of the global coherence of different types of droughts in model simulations under a high anthropogenic emission scenario

Abstract

This study provides a global analysis of drought metrics obtained from several climatic, hydrologic and ecological variables in a climate change framework using CMIP6 model data. A comprehensive analysis of the evolution of drought severity on a global scale is carried out for the historical experiment (1850-2014) and for future simulations under a high emissions scenario (SSP5-8.5). This study focuses on assessing trends in the magnitude and duration of drought events according to different standardised indices over the world land-surface area. The spatial and temporal agreement between the different drought indices on a global scale was also evaluated. Overall, there is a fairly large consensus among models and drought metrics in pointing to drought increase in southern North America, Central America, the Amazon region, the Mediterranean, southern Africa and southern Australia. Our results show important spatial differences in drought projections, which are highly dependent on the drought metric employed. While a strong relationship between climatic indices was evident, climatic and ecological drought metrics showed less dependency over both space and time. Importantly, our study demonstrates uncertainties in future projections of drought trends and their interannual variability, stressing the importance of coherent hydrological and plant physiological patterns when analysing CMIP6 model simulations of droughts under a warming climate scenario.