This Summer’s Heatwaves Would Have Been ‘Almost Impossible’ Without Human-Caused Warming, a New Analysis Shows

Widespread summer heatwaves like those currently baking the Northern Hemisphere, with temperatures soaring above 110 degrees Fahrenheit simultaneously in North America, Asia and Europe, will be common in just a few decades unless greenhouse gas emissions are immediately curtailed, an international team of scientists said Monday.

If global warming reaches 2 degrees Celsius above the pre-fossil fuel era, such heat waves will happen every two to five years, the researchers said as they released a rapid attribution analysis of the blistering conditions experienced by hundreds of millions of people in recent weeks. If emissions continue on the same increasing path as now for a few more years, the 2 degree Celsius mark will be passed in about 30 years, according to the new analysis by World Weather Attribution.

In the current climate, warmed by 1.1 degrees Celsius (1.9 Fahrenheit) by humans, these extreme heatwaves are no longer rare, “due to warming caused by burning fossil fuels and other human activities,” the authors wrote. “Events like these can now be expected approximately once every 15 years in North America, about once every 10 years in southern Europe and approximately once every five years in China.”

Their analysis also concluded that greenhouse gas pollution made the European heatwave 2.5 degrees Celsius (4.5F) hotter, the North American heat wave 2C (3.6F) hotter, and the heatwave in China 1C (1.8F) hotter. The heat in North America and Europe would have been “almost impossible” without global warming, while the heat in China was made 50 times more likely by the current level of greenhouse gas pollution. 

The researchers tested the effect of global warming against several different definitions of heatwaves, like duration and intensity, but that didn’t affect the result very much, said co-author Friederike Otto, a climate scientist with the Grantham Institute at Imperial College, London, who said the aim of the analysis is “to answer the question of the role of climate change in the immediate aftermath or while an extreme weather event is still occurring.”

A series of similar studies the last few years has helped the public understand that dangerous climate change impacts are happening now, not in some distant future, and that they will get worse. In each study, the team includes scientists from the affected regions, she said, adding that, while the current analysis hasn’t yet been peer-reviewed, similar studies in the past were all affirmed by scientific review panels.

“The role of climate change is absolutely overwhelming,” she said. “It’s not surprising these meteorological events are happening at the same time. You expect to see them in the Northern Hemisphere summer. Our emissions have been rising faster and faster in the last few years, so it’s not a surprise to see the responses happening faster and faster. We have known this for a long time and we see exactly what we expected to see.” 

Millions of Vulnerable People At Risk

What has become evident the past few years is that preparations for climate extremes are lagging. 

“The vulnerability of our social systems and of our ecosystems to changes in weather is something that has not been well researched in past decades,” Otto said. “But in the past five years or so, we have gained a huge amount of understanding to see that we are much more vulnerable than we might have liked to believe in the past.” Those adaptation shortcomings are a focus in the most recent report from the Intergovernmental Panel on Climate Change, as well as in the most recent adaptation gap report from the United Nations Environmental Program, she said.

There aren’t, however, any signs suggesting that greenhouse gas emissions will drop soon. The same day the attribution analysis came out, G20 countries failed to reach a deal on phasing out fossil fuels and government officials in the United Kingdom promised to extract all their remaining fossil fuel reserves in the North Sea, instead of trying to reduce fossil fuel production,  while the next global climate conference, COP28, is still set to be led by the head of a huge oil and gas company.

The findings were published as the extreme heat peaked in Southern Europe, with highs around 115 degrees Fahrenheit expected in Sicily, and with mass evacuations underway from wildfires on the Greek islands of Corfu and Rhodes, while repeated outbursts of giant, crop-busting hail storms hit parts of central Europe. In North America, waves of toxic wildfire smoke from Canada wafted over the eastern third of the country, and people suffered serious burns from touching hot surfaces in the Southwest. Overall, the past 20 days have been Earth’s warmest on record.

The death toll from this summer’s heat extremes will likely climb much higher as health records are tallied over the next few months. A recent study showed that, in the summer of 2022, more than 61,000 people in Europe died from heat-related causes.

“We need a cultural shift in the way we think about extreme heat,” said Julie Arrighi, interim director of the Red Cross Red Crescent Climate Centre. “Extreme heat is deadly and rapidly on the rise. To save lives, we need to look after the most vulnerable, which includes older people, people with underlying health conditions, people without housing, and communities with reduced access to cool spaces.”

Many communities still don’t have adequate heat warning systems or heat action plans, and they have not made the needed investments in long-term adaptation measures, including urban planning and strengthening the resilience of critical systems like health, electricity, water and transport, she added.

Otto emphasized that this summer’s heatwaves are not a new normal. 

“As long as we keep burning fossil fuels we will see more and more of these extremes,” she said. “Most important to remember is that they kill people, and they particularly kill and hurt and destroy lives and livelihoods of those most vulnerable. And politicians often claim they care about the normal people, the poor people, and those are actually the people who really suffer.” 

As confident as she is in the science, Otto said it only speaks to part of the issue.

“I don’t think there’s any stronger evidence that has ever been presented for a scientific question,” she added. “But often it’s not a scientific argument. It’s a political argument, what we care about and what we value. But if we would value people, it’s pretty obvious what we need to do.”