Warming Made Recent Heat Wave in U.S. and Mexico More Likely, Study Says

The deadly heat waves that began across Central America last month and moved up into Mexico and the Southwestern United States were made 35 times more likely by human-caused climate change, according to a new report by World Weather Attribution, an international organization of climate scientists.

Globally, heat waves are becoming more frequent, longer and hotter as levels of greenhouse gases in the atmosphere rise from the burning of fossil fuels for energy. This week, wide swaths of the United States have been experiencing record-breaking heat and dozens of people around the world have died amid intense heat during this year’s hajj pilgrimage.

“The results of our study should be taken as another warning that our climate is heating to dangerous levels,” Izidine Pinto, a researcher at the Royal Netherlands Meteorological Institute who worked on the analysis, said in a statement.

The scientists examined temperature data from five days of the hottest daytime and nighttime temperatures between late May and early June and compared recorded temperatures with a hypothetical planet in which humans had never pumped any greenhouse gases into the atmosphere.

The extreme heat the scientists studied was caused by a heat dome, where clear, sunny skies radiated the hot air trapped near the ground by a high-pressure weather system. The excessive temperatures were exacerbated by feedback loops caused by an ongoing drought, particularly in Mexico, and warmer ocean temperatures in the Pacific Ocean and the Caribbean.