Projected Changes in Increased Drought Risks over South Asia under a Warmer Climate

Every year, millions of people are at risk due to droughts in South Asia (SA). The likely impacts of droughts are projected to increase with global warming. This study uses the new ensemble mean of 23 global climate models from the Coupled Model Intercomparison Project phase 6 (CMIP6), population and gross domestic product (GDP) projections to quantify future changes in increasing drought risks and associated socioeconomic exposure across SA and its subregions under 1.5 degrees C and 2 degrees C of warming. We used two shared socioeconomic pathways (SSPs), SSP2-4.5 and SSP5-8.5. The most likely realization copula functions are used to model the joint distribution of drought severity and duration. Simultaneously, changes in the bivariate return period are calculated under a warming climate. The frequency of 50-year historical droughts (under a bivariate framework) might double across 80% of the SA land area under 1.5 degrees C of warming. Conversely, 12% of SA landmasses may suffer extreme droughts under 2 degrees C of warming. The severe drought episode frequency is expected to increase under 1.5 degrees C (40%-75%) and 2 degrees C (60%-90%) of warming relative to the recent climate. The largest exposure increase is projected in R2 and R4, then R1. Additionally, 75% (65%) of the SA population (GDP) could suffer from increased drought risks under the 1.5 degrees C warmer climate, whereas the additional 0.5 degrees C warming will lead to an unbearable regional situation. Limiting global warming to 1.5 degrees C compared with 2 degrees C can significantly reduce the drought risk influence in SA. These findings can help disaster-risk managers to adopt climate-smart management strategies.