Climate change is coming for Asia’s cities – Delhi’s heat is just a taste

Daytime temperatures (Opens in new window) in Delhi are peaking between 37°C and 45°C, with warm nights offering little respite. In late May, Delhi’s land surface temperature ranged from 31.59°C to 54.61°C, with a city-wide average of 43.15°C. Temperatures exceeding 50°C were recorded in different parts of the city (Opens in new window). On 25 May, Delhi recorded a night-time temperature of 32.4°C – its warmest night in 14 years.

In many countries, such conditions would trigger a public health emergency (Opens in new window), mandatory work-from-home arrangements, or adjusted business schedules to avoid the hottest parts of the day. Southern Europe has long adapted daily routines through the practice of the siesta (Opens in new window), shifting activity to the cooler morning and evening hours.

But in India, it is business as usual – and for a population already stretched thin by rising prices (Opens in new window), the heat constitutes another burden that people have little bandwidth to manage.

As one study (Opens in new window) notes:

“Delhi’s vulnerable communities, which constitute nearly 50% of the city’s population, do not have adequate means to adapt to rising heat and are impacted far more severely. They toil through the day to earn their daily bread – this becomes brutal when the nights do not provide any respite either.”

Delhi may be greener on paper, with environmental policies regularly enacted, but it is becoming less liveable in practice – a threat many Indian cities could face in the future.

A construction boom across Delhi has intensified the urban heat island effect. Urban heat islands (Opens in new window) occur when cities become warmer than surrounding areas due to the replacement of vegetation with concrete, asphalt and glass. The difference is tangible – a walk across a shaded lawn feels cooler than a walk on a concrete pavement under the same sun.

But the destruction of tree cover is not just a city problem. Global Forest Watch (Opens in new window) notes that India has lost 2.4 million hectares of tree cover since 2001, a 7% decline. The consequences are severe: rising heatwaves, shrinking habitats for wildlife, and degraded land cover under water stress.

Indian cities are heat traps in the making. Artificial landscapes (Opens in new window) absorb and store solar heat while eliminating the natural cooling provided by vegetation. The adverse consequences include rising energy consumption, and growing vulnerability to heatwaves. As climate change intensifies, addressing urban heat islands is a public health and urban governance imperative.

A study (Opens in new window) has noted that Delhi’s diurnal cooling – the difference between daytime and night-time temperatures – has shrunk by 9% over the last decade. A summer night that once brought temperatures down by around 12°C now offers less than 10°C of relief.

This has given rise to “cooling inequity (Opens in new window)”. As residents retreat into air-conditioned spaces, Delhi’s peak power demand has surged. Yet, air conditioners cool indoor spaces by expelling heat outdoors, warming surrounding neighbourhoods. For the informal sector – including construction and gig workers, street vendors and slum residents – a sleepless and sweltering night is not merely uncomfortable, a sleepless night translates into daytime exhaustion, reduced productivity and lost wages. This has led to “heat poverty (Opens in new window)” for roughly half of Delhi’s population, exacerbating (Opens in new window) the economic divide that defines Indian cities. Despite this, current heat action plans (Opens in new window) offer few measures to build resilient communities to manage the challenge.

Delhi’s heat is not just a weather problem – it is an urban governance challenge. Climate change has raised temperatures, but unchecked urbanisation, concrete sprawl, pollution and waste burning have intensified them.

Nor is the problem confined to Delhi. Heatwave management requires a whole-of-nation approach. Governments should stop treating ecology as a constraint on development and start treating it as a precondition for it. Tree cover, wetlands, and green corridors are not luxuries – they constitute tangible heritage (Opens in new window), doing work that no amount of concrete can replicate.

India does not have the capacity to keep paying for the loss of its green cover: neither in hospital beds, nor in disaster relief budgets. Building more while losing more is not a growth strategy. It is deficit spending on nature, and the interest rate is rising.

Practical solutions exist. India should adopt structured work hours for the informal sector, much like West Asia, where scheduling is designed around the sun to ensure workers’ safety. Global indicators such as the Wet Bulb Global Temperature Indicator (Opens in new window) should be incorporated into Indian policy assessments so that remedial measures can be taken. Resilient infrastructure should replace heat-absorbing concrete, and homes and offices should adopt reflective roof coatings (Opens in new window) that bounce back the sun's rays rather than absorbing them.

None of this is radical. What is missing is the urgency and the recognition that a city which cannot protect half its population from the heat is not seeing inclusive and meaningful development. And for the world’s most populous country on a warming planet, meeting the challenge at home should be seen as a prerequisite for its credibility internationally.