Future Projections of Heat Waves over India under CMIP6 Scenarios

Anomalous episodes of extremely high surface temperature are heat waves, observational studies have shown that heat wave characteristics like intensity, frequency, and duration are increasing regionally and globally. As heat waves inflict disastrous impacts on the livelihood of millions of people, it is critical in developing suitable mitigation strategies to curtail the socio-economic vulnerability. Future projections at the regional level will be crucial for climate risk management to policymakers. The present study addresses the changes in the heat wave characteristics over the seven temperature homogeneous zones of India, viz. North West, North Central, West Coast, East Coast, Interior Peninsula, Western Himalaya, and North East. We use the historical (1951-2014) and projections (2015-2100) of the Coupled Model Intercomparison Project phase-6 (CMIP6) under different climate change scenarios based on Shared Socioeconomic pathways, SSP126, SSP245, SSP370, and SSP585. The reliability assessment has been carried out and the selected model composite showed good skill than all model composite, in the multiple aspects of observed heat wave features over each zone. The findings show that the projected area of occurrence of extreme daily maximum temperature and long-lasting heat waves (>11 days) are considerably increasing over all zones, where the exacerbating increase is over West Coast under all climate change scenarios.  The heat wave days are likely to increase two times over Western Himalaya and North West,  while the warm days are increasing four-fold over West Coast and double over other zones under SSP370 and SSP585.  The projected changes in heat wave characteristics over North East is below the all-India average. High-intensity heat waves are probably over the coastal zones under the scenario SSP370 and SSP585. Currently, the least heat wave impacted West Coast,  likely to be more vulnerable in the future. The projections show the heat wave characteristics are increasing over all the zones and have a spatio-temporal variation.