Floating over the southeast U.S. is a thing called a “warming hole" — and it's not what it sounds like.
Despite the rest of the planet increasing in average temperature because of global warming, according to a Dartmouth study released Tuesday, there is an anomaly called the “U.S. warming hole” where temperatures are actually getting cooler.
The study believes that in the late 1950s, the jet stream over the U.S. became “wavier,” thus causing the polar vortex to cool down the Southeast U.S. While average global temperatures have increased about 1 degree Fahrenheit since 1958, that number has decreased by 1.2 degrees Fahrenheit in the “warming hole” during that same period.
During winter and spring, the warming hole floats over the southeast part of the country, resulting in cooler temperatures as “the polar vortex allows arctic air to plunge into the region,” according to the study. During the summer, the warming hole moves north to the Midwest, causing lower temperatures there.
“The recent extreme cold snaps in the Southeast, which seem counterintuitive to global warming, may be related to the U.S. warming hole," Trevor F. Partridge, a graduate student in earth sciences at Dartmouth and the study's lead author, said.
January’s winter storms Hunter and Inga — which passed across southeast states like Kentucky, Tennessee, and northern Alabama — are perhaps the most recent and telling examples of the “winter warming hole.”