Last week, Mexico recorded the hottest day in its history, scientists have stated, with temperatures in the Sonoran Desert hitting 125 degrees.

These extraordinary temperatures, measured by Shel Winkley, a meteorologist at Climate Central, were part of a deadly heat wave that has swept across Mexico, Central America and the Southwestern United States, killing 125 people.

There was no confirmation by the Mexico Meteorological Service on the recorded temperature. The organization was contacted for comment.

This heat wave was significantly intensified by humans burning fossil fuels, a recent study has revealed.

According to the World Weather Attribution, a collection of scientists that run rapid and non-peer reviewed climate attribution studies, soaring daytime and nighttime temperatures were made 35 times more likely and 2.5 degrees hotter due to the warming effects of burning fossil fuels. They calculated in the study, which measured temperatures recorded between June 3 and 9 and was released on Thursday, that not only is this extreme heat more intense but it is already much more frequent.

Imperial College London climate scientist Friederike Otto, who coordinated the attribution study team, said that the deadliness of this heat wave has been largely down to it failing to cool down at night, a crucial component for being able to survive boiling days.

According to Otto, climate change has made nighttime temperatures 2.9 degrees warmer and unusual evening heat 200 times more likely.

Otto told Newsweek: “We need to stop burning fossil fuels, we need to stop fighting stupid culture wars on the back of the poor, uneducated and most vulnerable.”

She added: “Cities need to have heat action plans that inform people about the dangers of heat, provide public spaces that are accessible where people can rest in the cool, public water fountains and a long-term strategy to increase the green space and decrease concrete in cities.”

In New York City, which is also experiencing a heat wave, the New York City Department of Parks & Recreation has been preparing ways to keep New Yorkers cool.

Press Officer Gregg McQueen, from the department, told Newsweek: “We have 850 spray showers in parks and 3,400 drinking fountains.

“On a hot summer day, shaded areas can be 20-45 degrees lower than unshaded areas. [the Department of Parks & Recreation] is on track to plant a record 18,000 trees this year—the most since 2016.”

In Veracruz, Mexico, Margarita Salazar Pérez, 82, told the Associated Press how she has been struggling to cope without air conditioning as temperatures climb, especially since it has remained so hot at night.

Citizens have even witnessed monkeys falling from trees in Mexico as the heat has become too oppressive even for them.

While this extreme weather event is still ongoing, the study has highlighted that such occurrences are becoming disturbingly common. Otto noted that heat waves, once rare and exceptional, are now frequent and severe, reflecting significant climatic shifts over the past two decades.

The study examined temperature records across a vast region, including southern California, Arizona, New Mexico, Texas, Oklahoma, and several Central American countries. Findings showed record-breaking temperatures, with San Angelo, Texas, reaching 111 degrees, and Corpus Christi experiencing unprecedentedly warm nights.

Using a combination of current and historical temperature data, the research compared scenarios with and without human-induced climate change, revealing the unmistakable influence of global warming on this year’s heat wave.

Professor Otto told Newsweek: “Given that this heat, particularly the U.S. part of it, was not a rare event it is quite likely that this was not the last heat wave this summer. It means more people will die.”

The immediate cause of this specific heat wave was a high-pressure system over central Mexico, which stifled cooling storms and clouds before shifting to the U.S. Southwest. Tropical Storm Alberto, which recently formed, is expected to bring rain to northern Mexico and southern Texas, potentially leading to floods.