Global heatwaves 'virtually impossible' without climate crisis: study

Blistering heat that has baked swathes of North America and Europe this month would have been "virtually impossible" without the impact of the climate crisis, researchers said, as intense temperatures spark health alerts and stoke ferocious wildfires.

In the new rapid analysis of the scorching temperatures on Tuesday, scientists from the World Weather Attribution group found that the heatwaves in parts of Europe and North America would have been almost impossible without "climate change."

"The role of climate change is absolutely overwhelming," said climate scientist Friederike Otto, of the Grantham Institute for Climate Change and the Environment, Imperial College London.

Heatwaves in China were made 50 times more likely by global warming, they found.

Scientists have already established that the climate crisis with about 1.2 degrees Celsius of global warming since the late 1800s has made heatwaves in general hotter, longer and more frequent.

To trace how far the July heatwaves in the northern hemisphere had departed from what would have been expected without that warming, Otto and her WWA colleagues used weather data and computer model simulations to compare the climate as it is today with that of the past.

Otto said in the past it would have been "basically impossible" that such severe heat waves would happen at the same time and that people should no longer be surprised to see temperature records tumbling.

More frequent heatwaves

The researchers found that these severe heatwaves can now be expected roughly once every 15 years in North America, every 10 years in southern Europe and every five years in China.

And they will become even more frequent happening every two to five years — if the temperature rise reaches 2 degrees Celsius, expected in around 30 years unless countries fulfil their Paris Agreement pledges and rapidly cut emissions.

The study also found that these heatwaves were hotter than they would have been without climate crisis.

This month, severe heatwaves have gripped southern Europe, Mexico, parts of the United States and China, with temperatures above 45 degrees Celsius.

Blazes on the Greek mainland and islands have caused tens of thousands to flee, sent tourists scrambling for evacuation flights and prompted the prime minister to say the country is "at war".

In Beijing, the government urged the elderly to stay indoors and children to shorten outdoor playtime to reduce exposure to heat and ground-level ozone pollution.

Meanwhile, intense temperatures have swept much of the southwest and southern United States including Phoenix, Arizona, which suffered a record-breaking three straight weeks of highs above 43C.