Deadly Indian heatwave made 30 times more likely by climate crisis

A vendor sits under a shade and waits for customers in Jammu, India, as temperatures reach 50C. Photograph: Channi Anand/AP

The heatwave scorching India and Pakistan has been made 30 times more likely by the climate crisis, according to scientists. Extreme temperatures and low rainfall since mid-March have caused widespread suffering, including deaths, crop losses, forest fires, and cuts to power and water supplies.

The study is the latest to show the already severe impacts of global heating on millions of people, even though the global average temperature has risen only 1.2C above pre-industrial levels to date. If it rises to 2C, heatwaves as intense as the current one would be expected as often as every five years in India and Pakistan, the scientists estimated.

March was the hottest in India since records began 122 years ago and Pakistan also saw record temperatures. March was also extremely dry, with 71% less rain than normal over India and 62% less in Pakistan. The heatwave intensified in April and peak temperatures of about 50C were seen in May.

The early onset of the heatwave and poor rains hit India’s wheat production and a subsequent government ban on wheat exports pushed global prices up 6%, adding to global food concerns. One farmer, Hardeep Singh Uppal, from the village of Baras in Punjab, said: “My wheat harvest this year was 50% less than expected. My crops have shrivelled from this heat.” Some respite is expected in north-west India on Monday and Tuesday, with forecasters predicting rain.

“The most distressing thing is that the limits to adaptation are being breached for a large poor population of the region at the present level of global warming,” said Dr Fahad Saeed, a climate scientist based in Islamabad working with the Climate Analytics group, and part of the study team.

“One can imagine how bad it would be even for a 1.5C warmer world,” he said. “Any warming beyond 1.5C can pose an existential threat for vulnerable populations in the absence of a strong adaptation and mitigation action.” India has implemented heat action plans in 130 cities and towns, which include early moves to prepare people and public services.

A separate study last week examined the record-breaking 2010 heatwave in India and Pakistan and found it was made 100 times more likely by the climate crisis. Other recent analyses showed devastating floods in South Africa and Europe, heatwaves in North America and the storms in south-east Africa were all supercharged by global heating.

The new analysis focused on the average maximum daily temperatures during March and April in north-west India and south-east Pakistan, the most severely affected regions. The scientists used weather data and computer models to compare how often heatwaves are likely to strike in today’s heated climate and in a world without human-caused global heating.

The researchers found that the current long-running heatwave is still a rare event even with global heating, with a 1% chance of happening each year. But they calculated that the climate crisis has made it about 30 times more likely. That means it would have been “extraordinarily rare” without the climate crisis, the scientists said.

“High temperatures are common in India and Pakistan, but what made this unusual was that it started so early and lasted so long,” said Prof Krishna AchutaRao at the Centre for Atmospheric Sciences at IIT Delhi. “People had little relief for weeks on end, with the costs particularly high for hundreds of millions of outdoor workers. We know this will happen more often as temperatures rise and we need to be better prepared for it.”

Dr Friederike Otto, at Imperial College London, the lead of the World Weather Attribution group behind the analysis, said: “In countries where we have the data, heatwaves are the deadliest extreme weather events. They are also the type of extremes most strongly increasing in a warming world. As long as greenhouse gas emissions continue, events like these will become an increasingly common disaster.”