Heat dome passes, but climate-fueled waves aren’t going anywhere

Climate change is making heat waves like the one that lingered over much of the U.S. this week more frequent and intense.

The Eastern U.S. sweltered under a heat dome in recent days, with some cities surpassing 100 degrees Fahrenheit. 

Roads in Delaware, Wisconsin and Missouri buckled, while a Virginia bridge malfunctioned and dozens of people in places including Washington D.C. and North Carolina were reportedly hospitalized. In New Jersey, some 100 people were treated after attending outdoor graduation ceremonies in the extreme heat. 

And while summer is always hot, man-made climate change is worsening the problem. Temperatures in parts of the country are set to soar again this coming week.

Megan Kirchmeier-Young, a research scientist at Environment and Climate Change Canada, told The Hill that as the planet warms up in a broader sense, extreme heat events become more likely.

“Warming, from human-caused climate change, means more days when we exceed particular temperature thresholds. Across most of the globe, hot extremes are becoming hotter and occurring more often. And we expect these trends to continue with continued global warming,” Kirchmeier-Young said in an email. 

“While we do not yet have results for this week’s event, Environment and Climate Change Canada’s rapid event attribution system analyzed many heat waves from last summer and found that all were more likely to occur because of human-caused climate change,” she added.

And not only is the entire planet warming, the Arctic is warming even faster.

Because of this, said Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan, the jet stream slows down and becomes curvier.

“This is where you start to get these high-pressure domes that just sit in one place longer,” he said, adding that “these very hot events are becoming more frequent because of that; they concentrate the heat in one large region.”

Michael Mann, a professor at the University of Pennsylvania’s earth and environmental science department, said in an email that the heat domes being experienced by the U.S and Europe “show that this was part of a very large-scale pattern, associated with a very ‘wiggly’ jet stream where the ‘wiggles’ stay in place for days on end.”

“It’s really a double whammy, the basic effect of warming the planet, plus how the pattern of warming is changing the jet stream, giving us those stuck, weather extremes, like the heat domes,” Mann said. 

He’s one of the authors of a paper published earlier this year that found that there has been a “threefold increase” in such events over the last 70 years, which has been “closely tied to amplified Arctic warming.”

“You’re potentially looking at that trend simply continuing on toward quadrupling, etc., as long as we continue to warm the planet with carbon emissions,” Mann told The Hill.

Kirchmeier-Young provided a different perspective, saying there’s some uncertainty in how weather patterns are changing. 

“The main factor for increases in the intensity and frequency of hot extremes is increasing temperatures. While specific weather patterns are important for the occurrence of any particular heat wave event, if/how these weather patterns might be changing is much more uncertain,” she said. 

But it’s not just the heat that causes misery during a heat wave, it can also be the humidity — something that Overpeck also said is being exacerbated by climate change.

“The atmosphere, because it’s warmer, it holds more moisture. And it’s that combination of the higher humidity, the water in the atmosphere and the heat that really makes it bad,” he said. 

The world’s average global temperature has already risen 1.36 degrees Celsius, or about 2.4 degrees Fahrenheit, when compared to preindustrial times, primarily due to manmade activity such as the burning of fossil fuels. 

But this is just a global average, and what people experience may be significantly hotter than just a few degrees.

“We still have warmer days and cooler days, but we are shifting the baseline, so the warmer days are even hotter than they used to be,” said Kirchmeier-Young. “It will not take much warming in the global temperature to see notable changes in extremes at the regional scale.”

“The average temperature of the planet is hard to feel, but for comparison, if we cooled the planet by four to five degrees C, we’d have an ice age, and that would be a totally different planet,” said Overpeck.

The heat wave came as the Trump administration is rolling back regulations meant to mitigate climate change — and as Congress prepares to repeal climate-friendly policies and incentives as part of Republicans’ “big, beautiful bill.”

“This heat wave that we’re just coming out of is a great example of we’re going to see more of getting even hotter and longer if we don’t slow down our use and stop our use of fossil fuels and replace fossil fuels with … clean, low-carbon energy,” Overpeck said.