How can India cope with heatwaves?

THE START of May in Delhi is a riot of colour. Red and yellow blossoms line the streets. But this year, no one is stopping to see the flowers. Almost everyone who can be is inside, parked in front of an air-conditioner or fan. For weeks India has been in the grip of a punishing heatwave. On 30th April, temperatures in the capital reached 43.5°C for the third day in a row. The heat has come unusually early, with the hottest March since records began in 1901. It is affecting a large area, including coastal areas and states at a higher elevation, which are normally cooler. In India and Pakistan, more than 1bn people are enduring excessive heat. Why is this happening, and how can the countries cope?

Heatwaves around the world have been made more common and hotter because of climate change, according to Friederike Otto, a climatologist at Oxford University. They will continue to get hotter until humans stop burning fossil fuels, Ms Otto adds. The world is on average 1.1-1.3°C warmer than in pre-industrial times, and the number of heatwave days India experiences (when the maximum temperature is 5°C or more above average) has also increased—from 413 in the decade to 1990 to 600 in the decade to 2020. Even if temperatures rise by less than 2°C above pre-industrial levels by the end of the century the Intergovernmental Panel on Climate Change (IPCC), a United Nations body, predicts that half of the global population will have been exposed to life-threatening heat and humidity. The most brutal impacts will be felt in cities, where the high density of buildings, asphalt and concrete, and the absence of vegetation creates extra-sweltering “heat islands”.

Cities must prepare properly. In India, Ahmedabad, in the western state of Gujarat, is best equipped. In 2010 an unusually severe heat wave killed an estimated 1,344 people in the city. Officials drew up a “heat action plan”—the first in south Asia—which launched in 2013 and has been updated frequently. An early-warning system alerts residents to coming heatwaves and tells health workers to prepare for an increase in admissions. If temperatures are high enough, it compels authorities to keep gardens and parks open for shade, install water dispensers and set up extra medical centres. Through the news media, text messages and billboards, residents are told how to cope with the heat and when to seek medical treatment. Since 2017 the local government has co-ordinated with schools and businesses helping staff who work outdoors to move their shifts to the cooler parts of the day.

One study suggests that the plan prevented around 2,400 deaths in the summers of 2014 and 2015 when there were several severe heatwaves. Several other Indian cities have since created their own plans at the behest of the national government. Improvements are often hampered by a lack of resources and the difficulty of getting different departments to work together. Cities that already have mechanisms to cope with natural disasters, such as those in Odisha, a state on the cyclone-prone eastern coast, tend to prepare best.

More preventative work is needed. Some building materials retain more heat than others, a problem that is particularly prevalent in India’s packed and poorly ventilated slums. Simple changes, such as painting roofs with solar-reflective paint, can lower indoor temperatures by several degrees. The government and several non-profit organisations are urging cities to do this after a successful pilot in Ahmedabad.

Heatwaves will keep getting more severe and harder to adapt to unless greenhouse-gas emissions reach net zero globally. But even if that happens people in countries like India and Pakistan will probably have to spend less time outside on the hottest days in decades to come. On May 1st Chennai, a city on the east coast, had a “wet-bulb” temperature (a function of heat and humidity that determines how fast water evaporates) of more than 32°C, the point at which it becomes difficult for people to cool down by sweating and physical labour becomes dangerous. Most people cannot survive wet-bulb temperatures above 35°C. India’s spring blossoms will command even less attention in the years to come. ■

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