Projected Changes in Socioeconomic Exposure to Heatwaves in South Asia Under Changing Climate

The risk of heatwave events and their persistence has intensified in recent past and is expected to increase faster in future. However, the anticipated changes in socioeconomic exposure to heatwaves are still unexplored. Here, we investigate the projected heat stress and associated socioeconomic exposure across South Asia (SA) and its subregions using the newly released ensemble mean of 23 global climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), population, and Gross Domestic Product (GDP) projections. We used two Shared Socioeconomic Pathways (SSPs), namely SSP2-4.5 and SSP5-8.5, and three-time periods, that is, near-term, midterm, and long-term relative to the base period (1985-2005). We found that SA region has the potential for widespread changes to Wet bulb globe temperature (WBGT) of 6.5 degrees C, which can exceed the theoretical limits of human tolerance by the mid of 21st century. The SA population's exposure significantly increases during midterm and long-term periods by similar to 750x106 10(6) person-hours under the SSP5-8.5 scenario. The GDP exposure is the greatest for the same period's up to 200x109 10(9) dollar-hours under the SSP2-4.5. Moreover, the foothills Himalayans and northern parts of Pakistan are presently unaffected by WBGT during midterm and long-term periods under both scenarios. Among subregions (hereafter R1, R2, R3, and R4), the frequency of subdaily WBGT is projected to increase in the region R2 and R4 by similar to 70% and similar to 90% under the SSP2-4.5 and SSP5-8.5 scenarios relative to the base period. The highest upsurge in exposure is anticipated for R2, including southern Pakistan and southwestern India, followed by R1 and R3. Notably, the climate effect is more dominant than the population, whereas changes in GDP effect contribute to the total change in GDP exposure.

Automated summary

The risk and persistence of heatwave events have intensified and are expected to increase faster in the future. This study investigates the projected heat stress and associated socioeconomic exposure in South Asia using climate models, population, and GDP projections. The findings suggest that the region is at risk of widespread changes in heat stress, with significant increases in population and GDP exposure.