The attribution study found that July heat waves are affected by climate change

Some of the temperature extremes recorded in the southwestern United States, southern Europe, and northern Mexico at the beginning of the month would have been “virtually impossible” without the impact of human-caused climate change, According to research released on Tuesday.

During the first half of July, hundreds of millions of people in North America, Europe and Asia were exposed to extreme heat waves. The researchers said that the probability of a heat wave in China is 50 times greater than climate change.

World Weather Attribution is an international group of scientists measuring the impact of climate change on extreme weather events, and focused on the worst temperatures so far during the Northern Hemisphere summer. In the United States, temperatures in Phoenix have reached 110 degrees Fahrenheit, close to 43 degrees Celsius, or higher for more than 20 days in a row. Many places in southern Europe are seeing record triple-digit temperatures. The temperature in a remote town in Xinjiang, China, reached 126 degrees, breaking a national record.

“Without climate change, we wouldn’t see this at all,” said Frederic Otto, senior lecturer in climate sciences at Imperial College London and co-founder of World Weather Attribution. Or it may be so rare that it basically won’t happen.

But in a climate altered by fossil fuel emissions, heat waves of this magnitude “are not rare events,” she said.

Before the Industrial Revolution, heat waves in North America and Europe were nearly impossible, according to the researchers’ statistical analysis. A heat wave in China would only happen once every 250 years.

If the composition of the atmosphere remains at current levels, the United States and Mexico can expect heat waves like the one that occurred last July about once every 15 years. In southern Europe, there would be a 1 in 10 chance each year of a similar event. In China, there is a 1 in 5 chance each year of a recurrence of the disease.

But as humans continue to burn fossil fuels and put more greenhouse gases into the atmosphere, the odds will continue to shift in favor of extreme heat: even if we stop, temperatures won’t cool down again, they will stop rising.

“The heat waves we’re experiencing right now, we definitely need to live with it,” said Dr. Otto.

As temperatures soared in Europe, Greece faced a wave of wildfires that forced the largest evacuations in the country’s history. Officials said the sweltering heat made firefighting efforts more difficult. More frequent and intense forest fires in the Mediterranean can also be linked to climate change, According to a recent study.

“We have increased risks from the heat,” said Julie Arighi, director of the Red Cross and Red Crescent Climate Center and a researcher with World Weather Attribution. “It’s fatal.” She stressed the need to adapt cities and critical infrastructure to extreme temperatures, but also to reduce greenhouse gas emissions at the same time.

Many local and national governments, especially in Europe, have developed heat action plans that include things like public cooling centres, advance warning and coordination between social services and hospitals.

But even where these programs exist they are imperfect and, at present, the human cost of temperature extremes remains high. The death toll from this month’s heat won’t be clear for a while, but more than 100 people have already died this summer in Mexico from heat-related causes, according to the national health minister. Last summer, nearly 61,000 people died across Europe from heat waves, according to another recent study.

The World Weather Attribution heatwave study has not been peer-reviewed, but the findings are grounded Standardized methods published in 2020. The group uses more than a dozen climate models to compare observed temperatures from the real world with typical projections of the planet without human-caused climate change.

“This methodology is pretty standard in the field,” said Andrew Pershing, vice president for science at the nonprofit group Climate Central. He was not involved in Tuesday’s study but has collaborated with World Weather Attribution in the past.

Dr Pershing said the extreme heat most of the planet is currently experiencing is “terrifying” in a historical context, but added that the consequences of the role of climate change are “not surprising”.

The first two weeks of July may have been the hottest on planet Earth, according to an analysis by the European Union’s Copernicus Climate Change Service. The National Oceanic and Atmospheric Administration expects unusually high temperatures across much of the United States in August.