Heat alerts for 60 million Americans Tuesday: Is climate change to blame?

The brutal, record-smashing heat wave that's been scorching northern Mexico and the south-central U.S., especially Texas, this month has a connection to human-caused climate change, experts said.

How brutal is the heat? On Tuesday afternoon, some 61 million Americans live where heat warnings, watches, or advisories were in effect, the National Integrated Heat Health Information System reported.

And all-time record high temperatures have been set or tied in Texas cities such as Del Rio (115 degrees), Laredo (115 degrees) and San Angelo (114 degrees) last week. The heat index, which is how hot it feels to the human body when humidity is factored in, reached an unofficial record of 125 degrees in Corpus Christi.

The death last week of a postal worker in Dallas, where the heat index reached 115 degrees, was blamed on the extreme heat. And a 14-year-old boy died after hiking with his stepfather and brother in extreme heat at Big Bend National Park in Texas on Friday as the temperature rocketed up to 119 degrees.

That was not only the nation's hottest temperature so far this year, according to weather historian Christopher Burt, but just missed the state's all-time record of 120 degrees, Weather.com reported.

Deadly heat: Texas postal worker collapses, dies amid extreme heat index over 110

Climate change made the heat wave five times more likely, study says

An analysis of data from Climate Central, a science communication group in Princeton, N.J., said that climate change is making this heat wave at least five times more likely.

"Human caused climate change made the extreme and extremely unusual temperatures in Mexico and the southern U.S. much more likely. Heat this intense, this early in the year will create stressful conditions for millions of people," said Andrew Pershing, vice president for science at Climate Central, earlier last week.

Climate Central's findings come from its Climate Shift Index, which is "a model-derived analysis of the likelihood of local temperatures with and without the influence of climate change, expressed on a simplified scale to quantify the degree to which carbon pollution affected average temperature," according to Peter Girard, the Vice President of Communications for Climate Central.

Texas is heating up due to climate change

In Texas, the epicenter of this heat wave, the average daily high temperatures have increased by 2.4 degrees – 0.8 degrees per decade – since 1993, according data from the National Oceanic and Atmospheric Administration. This comes amid concerns over human-caused climate change resulting in rising temperatures.

Looking far into the future, some 70 years from now, Texas is likely to have three or four times as many days per year above 100 degrees as it has today, the Environmental Protection Agency said.

Heat wave is 'extremely unusual'

University of Pennsylvania meteorologist Michael Mann told USA TODAY that this intense June heat wave is "extremely unusual. We’re seeing record heat indices (which combine the heat and humidity), for example (unofficially) 125 degrees in Corpus Christi."

Everything you need to know about heat: From the heat index to a heat dome to an excessive heat warning

Mann agrees that climate change is a factor in the heat wave, along with the natural warming from the El Niño climate pattern, but said "it’s difficult to parse out the precise roles of these things at present – that will require some additional diagnostic work.

"Climate change, as our own work shows, is leading to more of these very persistent 'stuck' summer jet stream patterns, where, for example, a big high-pressure system with hot sinking air gets stuck in one particular region of the country," Mann said. "That’s what happened during the 2021 Pacific Northwest heat dome and something very similar is playing out right now over the south central U.S. and northern Mexico."

"Sure, El Niño is having an impact right now on the large-scale atmospheric circulation, and could be playing a role in this current jet stream configuration. But El Niño has happened many times before without giving us such unprecedented weather extremes," he said.

What is a heat dome?

A heat dome occurs when a persistent region of high pressure traps heat over an area, according to William Gallus, professor of atmospheric science at Iowa State University.

"The heat dome can stretch over several states and linger for days to weeks, leaving the people, crops and animals below to suffer through stagnant, hot air that can feel like an oven," Gallus said in an article in the Conversation.

More about heat domes: Millions expected to suffer as heat dome expands beyond Texas this week: Graphics

Speaking about the current heat dome, WFLA-TV chief meteorologist Jeff Berardelli tweeted last week that "this configuration, likely enhanced by climate heating, is fueling a record heat dome so extreme that even experts are astonished!" He added that this heat dome is “basically impossible” without climate change.

Heat is a killer

Heat waves are less dramatic than other natural disasters such as tornadoes, hurricanes, flooding or even thunderstorms, but they kill more people in the U.S. than all other weather-related disasters combined – causing hundreds of deaths each year, according to the National Weather Service.

How long will this heat wave last?

The heat wave that has plagued the south-central U.S. for much of this month will continue through the end of the week and into the weekend, forecasters said.

But meteorologists from AccuWeather said the pattern that's keeping this stifling heat in place will begin to break down by later in the weekend. Temperatures are still likely to remain a few degrees above historical averages, but not nearly at the level of this week's searing heat.

Then, as the calendar turns to July, the nation enters what's historically the hottest month of the year for many areas.

Contributing: The Associated Press

This article originally appeared on USA TODAY: Texas' early heat wave fueled by climate change, experts say