Though it sounds like a factoid ripped straight from Ripley’s Believe It Or Not, experts confirmed that Jacksonville, Florida really was colder than Anchorage, Alaska on Tuesday. With strange weather fronts and severe storms blowing across the country, the biggest city in the frigid “Last Frontier” state hit 49 degrees. Meanwhile, parts of the so-called “Sunshine State” only eked out a high around 41 degrees. As the Associated Press succinctly put it, the weather is currently “upside down”.
The flip, it seems, is the result of a relatively common weather phenomenon, which many call a “polar vortex.” The poles of the Earth are chilled by a counter-clockwise current of cool air. But sometimes, that icy air swirls out of the pole. With the help of the jet stream, that wind flowing west to east along the northern rim of the planet, this storm has made its way southeast, coating Canada, the Northeast, and even Florida in snow.
At the same time, says Mark Serreze of the National Snow and Ice Data Center, a ridge over the extreme western United States actually protected parts of southern Alaska from the cold. Ridges like these are elongated regions of relatively high atmospheric pressure. The stable pressure conditions formed by the strong ridge don’t allow for the vortex to sweep into Alaska the way it has in eastern states. It’s this combination of an expanding vortex and a westerly ridge that had frozen iguanas literally falling from trees down south (while caribous, one likes to imagine, were sunbathing up north).
On December 28, President Donald Trump tweeted that expectations for the coldest New Year’s Eve on record showed he was right to withdraw from the Paris Climate Treaty, a coalition of nations seeking to combat climate change. While this might have felt true in New York’s Trump Tower or the White House in D.C. (both in the path of the polar vortex), Serreze says people in Alaska were scratching their heads, wondering where their typically chilly winter weather had gone and asking if climate change was the reason they could break out their t-shirts. This mistake is fairly common—studies indicate that people’s opinion of climate change varies according to the weather outside their window—but it’s a logical misstep worth avoiding.
Trump’s statement and others like it mistakenly conflate weather with climate. Both weather and climate describe the behavior of the atmosphere. But while weather reports emphasize short-term changes that last days, weeks, or months, climate scientists look at shifts spanning decades. “The reason we could have a phenomenon exist like this is because it’s winter,” Serreze says of the current cold snap. Though it may be frigid right now, he says, the average global temperature continues to rise, thanks in large part to humans burning carbon-containing fossil fuels. The same day Anchorage and Jacksonville temporarily swapped weather, the Associated Press reports, the globe was 0.9 degrees warmer than usual—and the Arctic (where this whole vortex thing started) was 6 degrees warmer than usual.
The next time you look out your window, remember the rest of the world is doing the same thing—but probably seeing something very, very different.