WASHINGTON (AP) — A breaking new study finds that human-caused climate change has turned up the thermostat and increased the likelihood of this month’s killer heat that scorched the American Southwest, Mexico and Central America.
Sizzling daytime temperatures that triggered cases of heatstroke in some parts of the United States were 35 times hotter and 2.5 degrees warmer (1.4 degrees Celsius) due to warming from burning coal, oil and natural gas, World Weather Attribution, a compilation. The number of scientists conducting rapid, non-peer-reviewed climate attribution studies was calculated Thursday.
“This is a bakery; you can’t stay here,” said 82-year-old Magarita Salazar Pérez, who lives in Veracruz, Mexico, in her home without air conditioning. Last week, the Sonoran Desert reached 125 degrees (51.9 degrees Celsius), the hottest day in Mexican history, according to study co-author Shel Winkley, a meteorologist at Climate Central.
Imperial College of London climate scientist Friederike Otto, who coordinated the attribution study team, said the situation was even worse at night, which was what made this heatwave so deadly. He said climate change is making nighttime temperatures 2.9 degrees (1.6 degrees Celsius) warmer and increasing the likelihood of unusual evening temperatures by 200 times.
Salazar Pérez said that there is no cool weather at night as people are used to. Doctors say cool night temperatures are key to surviving a heat wave.
At least 125 people have died so far, according to the World Weather Attribution team.
“This is clearly related to climate change, the level of intensity that we see, and these risks,” said study co-author Karina Izquierdo, a Mexico City-based urban consultant for the Red Cross and Red Crescent Climate Center.
The worrying part about this heat wave, which is technically still scorching the North American continent, is that it’s not that unusual anymore, Otto said. The group’s past studies have looked at extreme temperatures so much so that they found it’s impossible without climate change, but not so much this heatwave.
“From a weather standpoint, this wasn’t uncommon, but the impacts were really bad,” Otto told The Associated Press in an interview.
“The changes we’ve seen in the last 20 years, which seem like just yesterday, are so powerful,” Otto said. His study found that this heat wave is four times more likely to occur now than it was in 2000, when the weather was almost a degree (0.5 degrees Celsius) colder than it is now. “It seems a bit distant and a different world.”
While the global carbon emissions reduction target adopted by other international groups of scientists and countries in the 2015 Paris climate agreement refers to warming since the pre-industrial era in the mid-1800s, Otto said it’s more striking to compare what’s happening now with the year 2000.
“We’re looking at a changing baseline; what was once extreme but rare is becoming increasingly common,” said Carly Kenkel, Chair of Marine Research at the University of Southern California, who was not part of the attribution team’s study. He said the analysis was “the logical conclusion based on the data.”
The study looked at a wide swath of the continent, including Southern California, Arizona, New Mexico, Texas, Oklahoma, Mexico, Guatemala, El Salvador, Belize and Honduras, and the five hottest days and five hottest nights in a row. Otto said that in most of the region, these five days occur from June 3 to 7, and these five nights also occur from June 5 to 9, but in a few places the highest temperature starts on May 26.
For example, San Angelo, Texas, reached a record 111 degrees (43.8 degrees Celsius) on June 4. Between June 2 and June 6, nighttime temperatures at the Corpus Christi airport never dropped below 80 degrees (26.7 degrees Celsius); This is a record every night. Two days where the thermometer never dropped below 85 (29.4 degrees Celsius), according to the National Weather Service.
Between June 1 and June 15, more than 1,200 daytime high temperature records were tied or broken in the United States and nearly 1,800 nighttime high temperature records were reached, according to the National Center for Environmental Information.
The attribution team used both current and historical temperature measurements, comparing what happened with events that occurred during past heat waves. They then used the scientifically accepted technique of comparing simulations of a fictional world without human-caused climate change with current reality to reveal how much global warming contributed to the 2024 heat wave.
The direct meteorological cause was a high-pressure system parked over central Mexico that blocked cooling storms and clouds, then moved toward the southwestern U.S. and is now bringing heat to the eastern U.S., Winkley said. Tropical Storm Alberto formed Wednesday and is heading toward northern Mexico and southern Texas with some rainfall that could cause flooding.
Mexico and other places have been struggling with drought, water shortages and extreme heat for months. In Mexico, monkeys are falling from trees due to the heat.
Izquierdo said this heat wave has “exacerbated existing disparities” between rich and poor in America, and Kenkel agreed. In the night heat the disparities become really apparent because the ability to cool off with central air conditioning depends on how financially comfortable they are. said Kenkel.
This means that Salazar Pérez is quite unwell during this heat wave.
___
Félix Márquez in Veracruz, Mexico, and Teresa de Miguel in Mexico City contributed to this report.
___
Find more information about AP’s climate coverage at http://www.apnews.com/climate-and-environment.
___
Follow Seth Borenstein on X: @borenbears
______
The Associated Press’s climate and environment coverage receives funding from many private organizations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage at AP.org.