Delhi Lost Nearly Half Its Green Cover In A Decade As Heat Stress Engulfed Almost Entire City: Report

Delhi has lost nearly half of its green cover in the last decade, while heat stress has spread across almost the entire city, according to a new report that paints a stark picture of how rapid urbanisation is making India's capital increasingly difficult to cool.

The report, Making Delhi Heat-Resilient: A Roadmap with the Focus on Vulnerable Groups, released by the Centre for Science and Environment (CSE), found that 98.72 per cent of Delhi's area crossed the heat-stress threshold at least once between 2015 and 2024. More alarmingly, over three-fourths of the city, 75.78 per cent of its total area, has remained persistently heat-stressed during the decade.

The findings come as Delhi experiences increasingly intense and prolonged summers, with heatwaves becoming more frequent and nighttime temperatures remaining elevated for longer periods.

Delhi experienced a month of weather extremes in May, recording its hottest May in two years while also registering its cleanest air quality for the month in nearly five years. According to data shared by Indian Meteorological Department (IMD), the capital's average maximum temperature in May was 39.7°C, while the average minimum temperature stood at 25.8°C.

Parts of Delhi Touching 60°C

Using satellite-derived land surface temperature data, researchers found temperatures reaching as high as 60.77 degrees Celsius during summer months in locations such as the Indira Gandhi International Airport and other barren or sparsely vegetated stretches.

Several industrial clusters, including Bawana, Mayapuri, Anand Parbat, Libaspur and Mundka, have emerged as major heat hotspots. Even residential neighbourhoods across the city are routinely recording land surface temperatures between 44°C and 50°C.

The report identifies the walled city and its extensions, Karol Bagh, Kashmere Gate, Connaught Place, Uttam Nagar, Palam, Najafgarh, Budh Vihar, Bawana and Narela among the areas facing recurring heat stress.

"What is building up the heat stress is unplanned self-constructed housing and buildings," the report notes, highlighting the role of dense urban development, concrete surfaces and shrinking natural landscapes.

Delhi Is Losing Its Ability To Cool Down

One of the report's most concerning findings is that Delhi's ability to cool itself during the night is declining.

According to CSE's analysis, the city's diurnal cooling capacity, the ability to release heat accumulated during the day, has reduced by 9 per cent. The urban core now cools 3.8°C less than peri-urban areas.

This means residents are increasingly facing warmer nights in addition to hotter days.

The report found that Delhi breached its normal mean maximum temperature on 42 out of 50 occasions during summer months between 2015 and 2024, suggesting that the city is gradually shifting towards a "new and warmer normal."

Warmer nights are also driving greater dependence on air-conditioners, creating what researchers describe as a dangerous feedback loop. As more air-conditioners operate, they release waste heat into the surrounding environment, further raising ambient temperatures and increasing electricity demand.

Green Cover Shrinks, Natural Cooling Weakens

The report also links the growing heat burden directly to the shrinking of Delhi's natural cooling infrastructure. According to the analysis, the city's green cover declined from 25.36 per cent of its area in 2014 to just 14.14 per cent in 2024. Water-body footprints also reduced, shrinking from 1.25 per cent to 0.99 per cent during the same period.

Researchers noted that this decline has reduced the city's ability to naturally regulate temperatures.

The report cites findings that vegetation can reduce ambient temperatures by as much as 5.7°C, while water-bodies can cool surrounding areas by up to 5°C. Dense tree canopies are particularly effective, with previous studies showing they can lower land surface temperatures by around 10°C compared to sparsely vegetated areas.

The Yamuna River remains one of Delhi's few major heat-relief corridors, with areas around the river recording surface temperatures of roughly 33°C, significantly lower than many surrounding urban neighbourhoods.

However, researchers warn that the river's cooling influence is increasingly overwhelmed by the scale of urban heat across the city.

Even New Redevelopment Projects Are Heat-Stressed

The report also raises questions about the climate resilience of Delhi's newest urban projects. Among the locations identified as heat-stressed are Bharat Mandapam, the redeveloped East Kidwai Nagar housing complex, the World Trade Centre in Safdarjung and Netaji Nagar.

The findings suggest that redevelopment alone does not guarantee thermal comfort and that future projects will need to actively integrate cooling measures into urban design. "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 states.

The Heat Burden Falls On Workers And The Poor

The report highlights how rising temperatures are disproportionately affecting vulnerable populations. Nearly 80 per cent of Delhi's workforce is employed in the informal sector, where workers often spend long hours outdoors with limited access to cooling, drinking water or shade.

CSE found that 92 per cent of active construction projects are located in areas where land surface temperatures exceeded 45°C at least once between 2015 and 2024. More than three-fourths of these sites are situated in areas experiencing recurring extreme heat.

Street vendors face similar risks. Of the 643 marketplaces mapped by researchers, 84 per cent were found in areas experiencing recurring heat stress. All of Delhi's major wholesale markets, including Azadpur Mandi, fall within these heat-stressed zones.

The report also estimates that over 1.5 million residents living in Delhi's informal settlements face heightened vulnerability because of overcrowded housing, poor ventilation, limited tree cover and restricted access to cooling resources.

A Blueprint For A Cooler Delhi Exists

Despite the grim findings, researchers argue that solutions already exist within the city. Around 24 per cent of Delhi's area has consistently remained below the heat-stress threshold over the past decade. Many of these cooler zones are either green-blue spaces or low-density neighbourhoods with abundant tree cover.

Areas such as Lutyens' Delhi, Civil Lines and the Delhi Cantonment remain comparatively cool due to extensive vegetation and surrounding green corridors. The report's simulations of public spaces in Chandni Chowk, Connaught Place and Lajpat Nagar suggest that targeted interventions can dramatically reduce temperatures.

Dense-canopy trees reduced land surface temperatures by between 9°C and 15°C. Artificial shade structures reduced temperatures by 12°C to 21°C. When multiple interventions were combined, including tree cover, shading and reflective paving, surface temperatures fell by as much as 20°C.

The findings suggest that relatively straightforward urban design measures could significantly improve outdoor thermal comfort, particularly in high-footfall areas such as markets, transport hubs and commercial districts.

As Delhi prepares for hotter summers in the coming decades, the report argues that the challenge is no longer simply about responding to heatwaves. Instead, it is about redesigning the city itself so that it can remain habitable in a warming climate.