Human-induced climate change has made the scorching heatwave that gripped parts of India and Pakistan 30 times more likely, scientists say.
India and Pakistan have suffered extreme heat intermittently since March, which was the hottest in India since records began 122 years ago. Pakistan also reported record high temperatures.
Climate experts have repeatedly warned that heat waves are increasing in intensity and frequency across the world due to global warming, primarily caused by the burning of fossil fuels.
The increased likelihood of heat waves is of concern as these are the deadliest extreme weather events and also damage crops and livelihoods.
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At least 90 people are believed to have died in Pakistan and India due to extreme heat, while the true toll is likely much higher.
Meanwhile, India opted to ban wheat exports this month citing food insecurity after its crop suffered from the heat.
The group of international climatologists looked at weather data and climate models to compare the climate as it is today – after around 1.2 degrees Celsius of global warming since the industrial revolution – and the climate of the past.
They focused on average daily maximum temperatures in March and April in northwestern India and southeastern Pakistan, the regions most affected by the recent heat.
The analysis revealed that heat waves such as the one affecting the region are still rare, with a 1% chance of occurring every year.
However, scientists say climate change makes them about 30 times more likely, meaning such an event would have been “extraordinarily” rare without global warming.
If the global temperature rise reaches 2°C, a heatwave like this would be expected as often as once every five years, scientists have found.
Friederike Otto, senior lecturer in climate science at Imperial College London’s Grantham Institute, said the results of the World Weather Attribution study were rather conservative.
When asked why they differ from the UK Met Office study published last week, which found climate change is making record-breaking heatwaves in north-west India and Pakistan 100 times higher likely, she said there were two main reasons.
The first is the Met Office study focused on average temperatures in April and May while the World Weather Attribution study focused on March and April – because they were interested in the fact that the heatwave has produced at the beginning of the year.
The second was that the Met Office used one climate model and the World Weather Attribution used 20 different models. Still, the big takeaway is that climate change is a “real game changer” when it comes to heat waves, she said.
Dr Otto said heatwaves were the type of extremes that were increasing the most in a warming world.
“As long as greenhouse gas emissions continue, events like these will become an increasingly common disaster,” she said.
The landmark United Nations climate report released last August found: “It is virtually certain that extreme temperatures (including heat waves) have become more frequent and intense over most land regions since the 1950s. . »
The report said it had “high confidence” that human-induced climate change is the main driver of these changes.