Rising heat risks threaten over 76% of India's population
A recent study by the Council on Energy, Environment and Water (CEEW) has found that 57% of India's districts—home to over three-fourths of its population—are now at high to very high risk from extreme heat. The report, 'How Extreme Heat is Impacting India: Assessing District-level Heat Risk', issues a stark warning: heat stress is no longer a seasonal discomfort but an accelerating disaster.
Using a composite Heat Risk Index (HRI) developed for 734 districts, the CEEW study identifies Delhi, Andhra Pradesh, Goa, Kerala, Maharashtra, Gujarat, Rajasthan, Tamil Nadu, Karnataka, and Uttar Pradesh as the 10 most heat-risk-prone states and Union Territories. The report is based on 35 indicators including frequency of very hot days, warm nights, rising humidity, population exposure, urbanisation trends, and health vulnerabilities.
One of the study's most alarming findings is the rapid increase in very warm nights—defined as nights where minimum temperatures exceed the 95th percentile of historical norms. Over the past decade (2012–2022), nearly 70% of districts saw at least five more such nights per summer compared to the 1982–2011 average. In contrast, only 28% of districts experienced similar increases in very hot days.
Cities are bearing the brunt. Mumbai saw 15 additional very warm nights, Bengaluru 11, Bhopal and Jaipur 7 each, Delhi 6, and Chennai 4. This trend is largely attributed to the urban heat island effect, where concrete-heavy infrastructure traps heat during the day and releases it at night.
'Very warm nights prevent the human body from recovering after intense daytime heat. This significantly increases the risk of heat strokes and exacerbates conditions like hypertension and diabetes,' said Dr Vishwas Chitale, Senior Programme Lead at CEEW and co-author of the report.
The report also highlights a growing secondary risk: increasing relative humidity. The agriculturally dense Indo-Gangetic Plain has witnessed up to a 10% rise in humidity over the past decade. Cities traditionally considered dry, such as Delhi, Chandigarh, Kanpur, and Varanasi, are now recording humidity levels that push the 'felt' temperature several degrees above the actual reading.
'High humidity hampers the body's natural cooling mechanism—sweating—and elevates health risks even during moderately hot days,' said Arunabha Ghosh, CEO of CEEW. 'We're entering an era of prolonged heat, rising humidity, and dangerously warm nights. The science is unequivocal—we must act now.'
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Tamil Nadu among top heat-risk States in country; warmer nights put people at risk
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Time of India
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Time of India
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Kol, 5 Bengal dists at ‘high risk' for extreme heat: Study
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