Impact of heatwaves over the Indian Subcontinent: understanding the issues of climate, economy, and population.

The summer of 2024 highlighted the growing global concern over maximum temperatures, with the Indian subcontinent experiencing unprecedented heatwaves exacerbated by climate change. Heatwaves with sustained high temperatures and reduced DTR (Diurnal Temperature Range) severely impacted vulnerable populations. Hence, more studies of extreme temperatures over the Indian subcontinent are needed. The anomalous heating observed during April and May 2024, with temperatures peaking at 51°C in some urban areas, can be attributed to complex interactions among atmospheric factors, including aerosol optical depth (AOD), dust-AOD, shortwave and longwave radiation, total column ozone, and large-scale climate phenomena like El Niño. Low AOD and dust-AOD levels imbalance the radiative balance, intensifying surface heating by allowing more shortwave radiation to be absorbed by the Earth's surface while dry surface conditions hinder longwave radiation from escaping. Anomalously low total column ozone further altered the surface energy balance, contributing to the extreme temperatures. These conditions, combined with excessive afternoon heat exceeding threshold limit values (TLV) for safe working conditions, led to widespread heat-related illnesses, particularly among manual labourers and farmers. The heatwaves also placed unprecedented strain on India's power grid, with electricity demand reaching a record 156 billion units (BU) in May 2024, a 15% increase from the previous year, resulting in frequent power outages. India's energy demand in April-May 2024 surged by 34.5 BU, costing 100 billion. The findings underscore the urgent need for targeted climate adaptation and resilience strategies in the Indian subcontinent, where over 500 heatstroke-related fatalities were reported during 2024. Research Highlights: During El Niño years, extreme maximum temperatures exceeding 45°C, combined with reduced latent heat flux from dry surfaces and elevated sensible heating, drive anomalous nighttime warming and reduced diurnal temperature range. Densely populated regions with weaker economic conditions face heightened heat exposure risk due to limited cooling infrastructure and a high proportion of outdoor workers. Inadequate climate adaptation policies and low public awareness exacerbate heat-related morbidity and mortality, disproportionately impacting vulnerable populations. [ABSTRACT FROM AUTHOR]