Human-caused climate change is playing an “absolutely overwhelming” role in the extreme heatwaves that have swept across North America, Europe and China this month, according to a review by scientists published on Tuesday.
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Throughout July, extreme weather wreaked havoc across the planet, with temperatures breaking records in China, the United States and southern Europe, causing forest fires, water shortages and an increase in heat-related hospital admissions.
Over the weekend, thousands of tourists were evacuated from the Greek island of Rhodes to escape fires caused by a record-breaking heatwave.
Without human-caused climate change, this month’s events would be “rare”, according to a study by the World Weather Attribution, a global group of scientists that examines the role climate change plays in extreme weather.
“The temperature in Europe and North America is almost impossible without the effects of climate change,” said Izidine Pinto of the Royal Netherlands Meteorological Institute, one of the authors of the study, in a press briefing. “In China it’s about 50 times more likely to happen compared to the past.”
The World Weather Attribution group estimates that increased greenhouse gas concentrations are making the European heatwave 2.5 Celsius (4.5 Fahrenheit) warmer than it already is. They also increased the North American heatwave by 2C and the one in China by 1C.
As well as directly affecting human health, the heat has caused extensive crop damage and livestock losses, scientists say, with US corn and soybean crops, Mexican cattle, southern European olives as well as Chinese cotton all severely affected.
El Nino may have contributed to more heat in some regions, but an increase in greenhouse gases is the main cause, scientists said, and heatwaves will become more likely if emissions are not reduced.
They estimate that a prolonged period of extreme heat is likely to hit every two to five years if average global temperatures rise 2C above pre-industrial levels. Average temperatures are currently estimated to have risen by more than 1.1C.
“The events we are looking at are not unique to today’s climate,” said Friederike Otto, a scientist at the Grantham Institute for Climate Change in London, speaking at the briefing. “It’s not surprising from a climatological point of view, that these events are happening at the same time.”
“As long as we continue to burn fossil fuels we will see more and more of these surpluses,” he said. “I don’t think there is any stronger evidence that any science has ever presented for a scientific question.”