Cities aren’t perfectly efficient energy machines, you guys. They’re great, especially when transit and density make it possible for city dwellers to use less energy, but cities still release a lot of waste heat out of tailpipes and chimneys. And all that waste heat has to go somewhere.

shutterstock_125443697

According to a new study published in Nature Climate Change, that waste heat is disrupting the jet stream and warming up other parts of the world, thawing winters across northern Asia, eastern China, the Northeast U.S., and southern Canada. From Reuters:

That is different from what has long been known as the urban-heat island effect, where city buildings, roads and sidewalks hold on to the day’s warmth and make the urban area hotter than the surrounding countryside.

Instead, the researchers wrote, the excess heat given off by burning fossil fuels appears to change air circulation patterns and then hitch a ride on air and ocean currents, including the jet stream. …

[S]tudy author Aixue Hu of the National Center for Atmospheric Research in Colorado said in a statement that the excess heat generated by this burning in cities could change atmospheric patterns to raise or lower temperatures far afield.

Researchers say this is a “partial story” of where waste heat goes, but all that wandering heat adds up to, they say, a global temperature increase of about 0.02 degrees. I still love you, cities, but it wouldn’t hurt us to put on a sweater and take the bus, right?