New Delhi, May 23 -- While land surface temperatures around the Yamuna riverbanks hover at 33degC on a hot day, areas around the Indira Gandhi International Airport reach as high as 60.7degC - a 27-degree differential within the same city, according to a new study released on Thursday. The finding is part of a larger analysis that found nearly three-fourths of Delhi's land area has remained under recurring heat stress between 2015 and 2024, with industrial belts, dense residential neighbourhoods, and unplanned settlements emerging as worst-affected locations. The analysis, Making Delhi Heat-Resilient: A Roadmap with the Focus on Vulnerable Groups by the Centre for Science and Environment (CSE), estimated land surface temperatures across Delhi using a decade of Landsat satellite data. Land surface temperature measures the heat emitted by the ground and built surfaces, and can significantly exceed air temperature in densely built or industrial areas. The report found that industrial belts, dense residential neighbourhoods, and unplanned settlements emerged as the worst-affected locations, with the highest LST. Driving the change was the loss of green cover and water bodies across the city, replaced by built surfaces - concrete, asphalt, dense masonry - to absorb and retain solar heat with little relief. Of Delhi's 272 wards, 153 had more than 75% of their area under recurring heat stress; 82 had over 90%. Seventeen wards - among them Turkman Gate, Ballimaran, Bazar Sitaram, Baljit Nagar, Babarpur, Karawal Nagar East, Bindapur, Budh Vihar, Madhu Vihar, Shiv Vihar, and Kirari Suleman Nagar - were completely heat-stressed. The report's sharpest finding cuts against the assumption that new development insulates against heat. The Bharat Mandapam convention centre, the redeveloped East Kidwai Nagar housing complex, and the World Trade Centre in Safdarjung and Netaji Nagar were all identified as heat-stressed - performing no better than unplanned settlements. "As Delhi continues to redevelop, it will need to actively find ways to ensure that the new built-up fabric does not add to the entrapment of heat and instead, mitigates it," the report said. The Yamuna, the report noted, functions as a heat reliever - but a limited one. With land surface temperatures around it holding at 33degC, "its impact is like that of a drop in an ocean." The study identified the weakening of Delhi's natural cooling systems - green cover and water bodies - as a compounding factor, and called for an active management approach combining city-level infrastructure interventions with targeted measures for vulnerable populations. Among its recommendations: that Delhi formally recognise heat as a disaster, enabling access to the State Disaster Response Fund; and that thermally efficient cool roofs be mandated across industrial areas, office complexes, markets, and informal settlements, where they can reduce indoor temperatures by up to 5degC....