July 2023 is expected to be the hottest month ever recorded, climate scientists say

The fingerprints of climate change are all over the intense heat waves gripping the globe this month, a new study finds.

Researchers say the deadly hot spells in the American Southwest and Southern Europe could not have happened without the continuing buildup of warming gases in the air.

Thanks to years of research and more powerful computers, scientists can now determine almost in real-time whether climate change is contributing to the intensity of heat, storms, floods and drought - and by how much.

A generation ago, calculating such connections took up to a year, but researchers at World Weather Attribution made their conclusions about this summer's heat wave in less than a week. Their study is the first to look at three simultaneous heat waves on three different continents.

These unusually strong heat waves are becoming more common, Tuesday's study said. The same research found the increase in heat-trapping gases, largely from the burning of coal, oil and natural gas has made another heat wave - the one in China - 50 times more likely.

A stagnant atmosphere, warmed by carbon dioxide and other gases, made the European heat wave 4.5 degrees Fahrenheit hotter, the one in the United States and Mexico 3.6 degrees Fahrenheit warmer and the one in China 1.8 degrees Fahrenheit toastier, the study found.

“Had there been no climate change, such an event would almost never have occurred,” said Mariam Zachariah, a climate scientist at Imperial College of London and the lead author of the study. She called heat waves in Europe and North America “virtually impossible” without the increase in heat-trapping gases since the mid-1800s. Statistically, the one in China could have happened without global warming.