With 2024 on track to become the hottetst year on record—surpassing even the unsettling heat of 2023—some regions are having to contend with a new phenomenon that neither climate models nor climate scientists can explain.
Researchers in the U.S. and Austria have created the first world map highlighting regions repeatedly experiencing intense heat waves that greatly exceed global warming models. The map, detailed in a November 26 study published in PNAS, shows these unexplainable hotspots residing on every continent, save for Antarctica. Alarmingly, the associated heat waves have killed tens of thousands of people and destroyed environments by causing droughts and wildfires, according to a Columbia Climate School statement.
“This is about extreme trends that are the outcome of physical interactions we might not completely understand,” Kai Kornhuber of the International Institute for Applied Systems Analysis in Austria and lead writer on the study said in the statement. “These regions become temporary hothouses.” Kornhuber is also an adjunct scientist at the Columbia Climate School’s Lamont-Doherty Earth Observatory.
The Columbia-led team focused on unexpected heat waves over the past 65 years, though most occurred in the last half a decade. This approach identified regions where the temperature increase is accelerating quickly and has repeatedly broken maximum records with room to spare. For example, in 2021, a nine-day heatwave in the U.S. Pacific Northwest and southwestern Canada broke some local daily records by 54 degrees Fahrenheit (30 degrees Celsius).
More broadly, the map marks hotspots in central China, Japan, Korea, the Arabian peninsula, eastern Australia, parts of Africa, Canada’s Northwest Territories and its High Arctic islands, northern Greenland, the southern end of South America, and parts of Siberia, with the most extreme and consistent in northwestern Europe, where fewer people have air conditioning than in the United States.
“The large and unexpected margins by which recent regional-scale extremes have broken earlier records have raised questions about the degree to which climate models can provide adequate estimates of relations between global mean temperature changes and regional climate risks,” the researchers wrote in the study. In other words, the rising average global temperature might not reflect the extreme heat reality of certain local climates in the way that models predicted.
What makes the phenomenon even stranger is that it is not occurring everywhere. Though regions including parts of north-central United States, south-central Canada, and South America, as well as much of Siberia, northern Africa, and northern Australia also have rising temperatures, their peaks are lower than those forecast by models.
Scientists don’t know what’s causing this disparity. A previous study led by Kornhuber hypothesized that changes in the northern jet stream (strong winds that circle the Earth from west to east) were to blame for the hotspots in Europe and Russia, but the theory doesn’t explain all the extremes, according to the new research. Another 2021 study led by Columbia University graduate student Samuel Bartusek, who is also a co-author of the new study, also suggested factors behind the 2021 Pacific Northwest/southwestern Canada heat wave, including similar disruptions to the jet streams, drying vegetation without water reserves to evaporate, and atmospheric events that brought heat from the Pacific Ocean surface to land.
“Due to their unprecedented nature, these heat waves are usually linked to very severe health impacts, and can be disastrous for agriculture, vegetation and infrastructure,” Kornhuber concluded in the statement. “We’re not built for them, and we might not be able to adapt fast enough.”
Though the United States is better equipped than other countries to handle spiking temperatures, heat nevertheless takes the lives of more people in the U.S. each year than any other extreme weather event. With COP29 having just come to a close, it remains to be seen how nations will act to mitigate the impact of climate change on the world’s most vulnerable communities.
