“It’s pretty disastrous if it doesn’t clear up overnight,” said Matt Salerno, a meteorologist at the National Weather Service.

The length of the Phoenix heatwave is also noticeable in the summer, when much of the southern United States and the rest of the world are experiencing record temperatures, which scientists claim is caused by climate change. .

Experts say what’s happening in the metropolitan area known as the ‘Valley of the Sun’ is far more serious than the temporary rise in thermometers and poses a health risk to many. .

“Prolonged exposure to heat is more difficult to endure than a full day of hot weather, especially if it’s not cool enough to sleep well at night,” said Catherine Jacobs, director of the center. Even more so,” he said. Climate Adaptation Science and Solutions Center at the University of Arizona.

“This season is going to be one of the most notable in our health record in terms of deaths and illnesses,” said David Hondura, City of Phoenix’s heat management chief. “Our goal is to prevent that from happening.”

The last time Phoenix did not reach 110 degrees Fahrenheit (43.3 degrees Celsius) was on June 29, when it hit 108 degrees Fahrenheit (42.2 degrees Celsius). The record for 18 days above 110 degrees Celsius alongside a Monday was first set in 1974, but with temperatures expected to rise above it over the weekend, the record seemed destined to be broken.

“It’s very persistent,” says National Weather Service meteorologist Isaac Smith. “We are going to see this trend continue.”

No other major U.S. city boasts 110 degrees Celsius during the day and 90 degrees at night like Phoenix, according to weather historian Christopher Bart of The Weather Company.

NOAA climate data scientists Russ Vose and Ken Kunkel said no major city had such a sustained heat wave, but death valley and Needles in California and Casa Grande in Arizona. Smaller locations were found to be experiencing longer periods of extreme heat. Death Valley has had 84 consecutive days of 110 degrees Celsius and 47 consecutive days with nighttime temperatures not below 90 degrees Celsius, Vose said.

Randy Cerveny of Arizona State University, who coordinates weather record verification for the World Meteorological Organization, said the Phoenix heatwave has long-term and short-term causes.

“The long-term cause is that temperatures have continued to rise over the last few decades due to human influence on the climate, but the short-term cause is that a very strong high pressure system has spread over the western United States in recent weeks. It’s going on.”,” he said.

The anticyclone, also known as the heat dome, has been in the southwest for weeks, and as it moved, it became more concentrated in Phoenix than ever before, Smith said.

The entire southern United States is under a hot dome, temperature records are being shattered from California to Florida, and the planet itself is the hottest on record for much of summer.

A high pressure system in the southwest is also preventing cold rain and clouds from providing relief, Smith said. The southwestern monsoon season usually starts around mid-June, with rain and clouds. But Phoenix hasn’t had any measurable rain since mid-March.

“Phoenix summers are always hot, but this heat wave is intense and unrelenting,” Jacobs said. “Unfortunately, given that the most credible projected impacts of climate change are those directly related to global warming, this is a harbinger of things to come.”

According to NOAA, since 1983, Phoenix’s summer average daily temperature has increased by 3.6 degrees (2 degrees Celsius), with daytime highs of 3.2 degrees (1.8 degrees Celsius) and nighttime lows of 4.4 degrees (2.4 degrees Celsius). degree) is rising. .

“Climate change and urban heating are definitely exacerbating warming and making it more frequent,” Smith said.

And it is dangerous for many groups.

“Heatwaves are deadly, especially for homeless people, those who work outdoors, or those with inadequate air conditioning,” Jacobs said. “It’s especially difficult for older people and those with underlying medical conditions to stay hydrated.”

Such heat can hit the country of India especially hard. Jacobs said about 30 percent of the population on the Hopi and Navajo reservations have no running water or air conditioning, nor are they near cooling centers. This is particularly unfair, she says, because “tribal members contribute little to greenhouse gas concentrations.”

Another aspect of heatwaves that disproportionately affects certain communities is the urban heat island effect, where cities are warming due to a lack of buildings, trees and green space, said a professor of health and environment at the University of Wisconsin. Dr. Jonathan Patts said. Madison.

a research published Two years ago, the journal Nature Communications found that people of color were exposed to extreme temperatures more than non-Hispanic whites, and that the poor had to deal with higher temperatures than the rich. made it

Hispanic-majority neighborhoods in Phoenix tend to have less tree canopy than other areas of the city.

And one of the city’s hottest neighborhoods is Edison Eastlake. It’s a historically black neighborhood east of downtown, with a large Latinx population and some of the hottest temperatures in recent years. 10 degrees higher than other areas of the city.

Researchers at Arizona State University are conducting a thermal study of Arizona’s largest cluster of public housing, and temperatures will moderate as redevelopment progresses to better protect residents from extreme heat. are measuring whether No conclusions have been published to date.

Hondura, a thermal manager in Phoenix, had participated in the study as a university researcher several years earlier.

“It’s clear that the heat is having a disproportionate impact on some communities, and that’s where we can and should work,” he said.

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For AP’s climate and environmental coverage, please visit: https://apnews.com/hub/climate-and-environment

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Mr. Borenstein reported from Washington. Follow Seth Borenstein and Anita Snow on Twitter. @borenbears and @asnowreports

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