Skip to main content

Sign up for our newsletter.

Quality journalism. Progressive values. Direct to your inbox.

Pakistan heatwave

Patients suffering from heat stroke are treated at a hospital in Jacobabad, southern Sindh province, Pakistan on May 11, 2022. (Photo: Aamir Qureshi/AFP via Getty Images)

Heatwaves Rated 'Extremely Dangerous' Could Triple This Century, Warns New Climate Study

"Something that's gone from virtually never happening before," said one Harvard researcher, "will go to something that is happening every year."

Brett Wilkins

As record-breaking high temperatures and historic droughts afflict millions of people around the world, a study published Thursday warned that by the end of the century, dangerous heat driven by the worsening climate emergency will hit much of the Earth at least three times more often than today.

"The kinds of deadly heatwaves that have been rarities in the midlatitudes will become annual occurrences."

The study—conducted by climate researchers at Harvard University and the University of Washington and published in the journal Nature Climate Change—shows how changes in the heat index driven by human carbon dioxide emissions will dramatically increase exposure to "dangerous" and "extremely dangerous" temperatures. The heat index is a measure of how hot it really feels, based on temperature and relative humidity.

The U.S. National Weather Service defines heat index temperatures over 103°F as "dangerous" and over 124°F as "extremely dangerous."

Study co-author David Battisti explained to The Conversation that "'dangerous' in this case refers to the likelihood of heat exhaustion. Heat exhaustion won't kill you if you're able to stop and slow down—it's characterized by fatigue, nausea, a slowed heartbeat, possibly fainting. But you really can't work under these conditions."

"If a person gets to 'extremely dangerous' temperatures, that can lead to heat stroke," he added. "At that level, you have a few hours to get medical attention to cool your body down, or you die."

The study's abstract states that "even if the Paris agreement goal of limiting global warming to 2°C is met, the exposure to dangerous heat index levels will likely increase by 50-100% across much of the tropics and increase by a factor of 3-10 in many regions throughout the midlatitudes."

"Without emissions reductions more aggressive than those considered possible by our statistical projection, it is likely that by 2100, many people living in tropical regions will be exposed to dangerously high heat index values during most days of each typical year, and that the kinds of deadly heatwaves that have been rarities in the midlatitudes will become annual occurrences," the summary continues.

Midlatitude places the study says will experience a 3- to 10-fold increase in heat index levels include the United States, Western Europe, and China. Parts of all three places are currently gripped by either historic drought, record temperatures, or both

Climate scientists stress that the severity of future heatwaves depends on whether humanity can sufficiently reduce greenhouse gas emissions.  

Study lead author Lucas Vargas Zeppetello—whose team conducted much of its research in Washington state during last summer's historic heatwavetold The Guardian that a failure to dramatically slash emissions "is just hugely consequential for billions of people, primarily throughout the Global South."

"So that's kind of the scary thing about this," Zeppetello said in a separate interview with the Associated Press. "Something that's gone from virtually never happening before will go to something that is happening every year."

On Thursday, the Climate Crisis Advisory Group (CCAG) said that "the record-breaking heatwave experienced across Europe this summer will be considered an 'average' summer by 2035, even if countries meet their current climate commitments" under the Paris agreement.

"In the aftermath of the 2003 European heatwave, which is estimated to have killed over 70,000 people, I predicted that such temperatures, so exceptional at the time, would become the norm under continued emissions," Peter Stott, a professor at the U.K. Meteorological Office's Hadley Center, said in response to the new CCAG findings.

"That prediction has now been realized," he added. "The risks of extreme weather, including fires, drought, and flash floods, will keep increasing rapidly unless emissions of greenhouse gases are reduced substantially."


Our work is licensed under Creative Commons (CC BY-NC-ND 3.0). Feel free to republish and share widely.

We've had enough. The 1% own and operate the corporate media. They are doing everything they can to defend the status quo, squash dissent and protect the wealthy and the powerful. The Common Dreams media model is different. We cover the news that matters to the 99%. Our mission? To inform. To inspire. To ignite change for the common good. How? Nonprofit. Independent. Reader-supported. Free to read. Free to republish. Free to share. With no advertising. No paywalls. No selling of your data. Thousands of small donations fund our newsroom and allow us to continue publishing. Can you chip in? We can't do it without you. Thank you.

'Incredible': Omar and Khanna Staffers Join Levin's Office in Unionizing

"It is long past time the United States Congress became a unionized workplace, and that includes my own staff," said Rep. Ilhan Omar. "I am proud of all the people on my team who have played a leading role in the staff unionization effort. Solidarity forever."

Jessica Corbett ·


Destructive Hurricanes Fuel Calls for Biden to Declare Climate Emergency

"Mother Nature is not waiting for the president or Congress to declare a climate emergency. She's showing us in real-time here in the United States—with wildfires, floods, heatwaves, hurricanes, and drought."

Jessica Corbett ·


Spain Approves 'Solidarity' Tax to Make Nation's Top 0.1% Pay a Fairer Share

The country's finance minister said that looming changes are bound to make the tax code "more progressive, efficient, fair, and also enough to guarantee social justice and economic efficiency."

Kenny Stancil ·


'Time to Take to the Streets': Working Class Hold 'Enough Is Enough' Rallies Across UK

"Does a CEO need an extra zero at the end of their salary—or should nurses, posties, and teachers be able to heat their homes?" said one supporter ahead of the #EnoughIsEnough National Day of Action.

Julia Conley ·


Ukraine Responds to Putin Annexations With Fast-Track NATO Application

Lamenting the lack of any progress toward a diplomatic settlement, one anti-war campaigner asked: "Will the world stand idly by as we careen towards nuclear apocalypse?"

Jake Johnson ·

Common Dreams Logo