A silent killer? From hotspots to heat-resilient cities: India’s urban challenge

By Sumeet Agarwal 

South Asia stands at the frontline of the global heat crisis, with climate change driving longer, more frequent, and more intense heatwaves across the region. The IPCC’s Sixth Assessment Report identifies South Asia as among the world’s most heat-vulnerable zones, and India’s escalating urban heat stress is a stark reflection of that reality. The summer of 2024 was among the hottest on record, with Delhi breaching 46°C and the Indo-Gangetic Plain sweltering under prolonged heatwave conditions. Yet even these record temperatures tell only part of the story; in Indian cities the burden of heat is highly uneven. 

Poorly planned neighbourhoods trap heat through the Urban Heat Island effect, where concrete, asphalt, and metal roofing absorb and radiate solar energy. In informal settlements, indoor temperatures can exceed outdoor temperatures by 8–10°C, posing severe health risks, particularly for children, the elderly, and women. Recognising these dangers, India’s National Disaster Management Authority has formally designated heatwaves as a national disaster, underscoring the urgency of adopting community-centred mitigation strategies.

As world leaders gather for COP30 in Brazil, adaptation to a hotter planet is at the core of global debate. In this context, efforts by organisations such as the Sustainable Environment and Ecological Development Society (SEEDS) offer relevant lessons for the Global South. Their community-centred approach to heat resilience, especially in the Delhi National Capital Region, reflects the spirit of the recent G20 Ministerial Declaration on Disaster Risk Reduction, which endorsed the principle of “Resilience of All.”

Urbanisation, dense construction, and shrinking green spaces have turned cities in the Global South into heat traps. According to the Indian Meteorological Department, heatwave days in India have more than doubled since 1980. Cities such as Delhi, Ahmedabad, and Hyderabad now face longer and more intense heat events, but their impacts fall disproportionately on the urban poor. Nearly 65 million Indians—17 percent of the urban population—live in slums characterised by tin or asbestos roofs, limited ventilation, overcrowding, and almost no access to shade or open spaces. 

During peak heat, indoor temperatures often exceed 45°C, even at night. In single-room homes, dehydration, sleep deprivation, and heat exhaustion become routine realities. Unreliable electricity and water supply worsen the distress, while makeshift water storage in plastic containers traps additional heat. Rising expenses and declining productivity deepen existing economic vulnerabilities.

Migrant workers in construction, street vending, sanitation, and delivery services face extreme occupational exposure. Long hours under direct sunlight, often without rest, hydration, or shelter, make them particularly prone to heat exhaustion and fatal heatstroke. The NDMA estimates that extreme heat can reduce labour productivity by 15–20 percent, especially in informal sectors where lost workdays translate directly into income loss. 

Prolonged heat exposure has clear physiological consequences: dehydration, heatstroke, cardiovascular and respiratory aggravation due to elevated ozone and particulate levels, and declines in mental health and sleep quality. The World Health Organisation identifies the urban poor as climate-vulnerable populations requiring priority adaptation interventions, a recognition that India must incorporate into its urban policy frameworks.

Mitigating heat in cities requires immediate relief as well as long-term structural solutions. Urban design improvements, expanded green infrastructure, restored waterbodies, reflective materials, cool roofs, and permeable surfaces all help reduce heat stress and improve microclimates. Blue-green infrastructure—connecting parks, lakes, and shaded corridors—is now being incorporated into the urban plans of cities such as Ahmedabad, Chennai, and Pune. 

Building-level interventions, including cool roofs, roof insulation, shaded verandas, and cross-ventilation, can dramatically lower indoor temperatures at low cost. Heat Action Plans in cities like Ahmedabad, Delhi, and Hyderabad integrate early warning systems, community outreach, and coordination across agencies, providing a template for broader national adoption.

Across Delhi, community-focused interventions are demonstrating practical pathways for heat mitigation. Through the Under the Umbrella campaign launched in 2024, SEEDS and community volunteers have raised awareness about heat risks, promoted simple cooling measures, and connected residents to safe shelters. In Kishan Kunj, an informal settlement in East Delhi, cool roof treatments using reflective materials and insulation have significantly reduced indoor temperatures. 

Heat alerts and educational materials are shared in local languages through community networks, ensuring timely and accessible information. Partnerships with community health workers and local leaders help reinforce practices related to hydration, rest, and care for the elderly and children.

Working with residents, SEEDS has implemented lime-based cool roofs in low-income settlements in northwest Delhi, offering a low-cost, high-impact solution. The organisation also uses AI and GIS tools to map building-level heat risks, analysing satellite and land-surface temperature data to identify the most vulnerable homes. These insights help target interventions efficiently and build evidence for policy replication. Community-driven “living laboratories” have emerged in neighbourhoods such as Kishan Kunj, where residents co-design solutions—shaded streets, insulated homes, refurbished drinking water points, and worker shelters. 

These measures not only reduce heat exposure but strengthen overall liveability, offering a model that other cities can adapt. At the city scale, restoring degraded waterbodies has proved essential. SEEDS has revived one lake in Delhi and three in Gurugram, helping stabilise local microclimates and benefiting thousands of residents.

These experiences highlight critical lessons: built form significantly shapes heat exposure; community agency is crucial for sustaining interventions; large-scale adoption requires alignment with urban planning, policy, and financing; data-driven mapping improves targeting; and heat resilience must integrate housing quality, socio-economic conditions, and health.

Building truly heat-resilient cities will require India to embed these principles into urban planning, housing design, and climate adaptation frameworks. What are today pilots must become tomorrow’s urban standards. Sustainable, inclusive, and climate-smart urban design is not merely about cooling cities—it is, increasingly, about safeguarding lives.

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The writer is Director of the Built Environment, Sustainable Environment and Ecological Development Society (SEEDS)