Depending how you see it it, January and February were either pretty great—or pretty crappy. For the first time in 146 years, Chicago saw no snow on the ground in those two months.
Sure, it gave a jump start to patio season, but murmurs across the city about global warming dampened all those Instagrams from the beach. We wanted to know: is the mild weather a sign of impending climate doom?
Both Ryan Sriver, assistant professor of atmospheric sciences at the University of Illinois Urbana-Champaign, and Daniel Horton, assistant professor of earth and planetary sciences at Northwestern University, say the answer is no.
Don’t get too comfortable, though.
Just two months of abnormal weather can’t prove anything on their own, the climate experts say. However, the Earth is setting more record-high temperatures than record-low temperatures lately, and that is a sign of global warming.
According to Horton, weather variability is natural in Chicago due to its location in the mid-latitudes, “the middle segment of the Earth where the weather is controlled by an oscillating jet stream,” which are slim strips of wind. This means that naturally, Chicago will have more irregularity in weather, as compared to the area near the equator, where temperatures are steady and predictable.
Temperature differences can change the location of the jet stream, Sriver says. So, when higher latitude regions (read: the Arctic Circle) warm up faster due to environmental and human factors, the jet stream will move. Because the jet stream is going farther north right now, this means warmer temperatures in Chicago, according to Sriver.
This isn’t always the case, Sriver says. Two years ago, the jet stream went farther south, and in turn, we got the polar vortex.
In fact, Chicago has seen an overall upward trend in temperatures, Horton says. Put simply, if you were to plot the temperatures during winter on a graph, the trend line should be horizontal—but instead, the line has an upward slope.
Other signs of global warming: “When we do have precipitation, then there’s a higher likelihood that it will be rain versus snow, and spring conditions show up earlier in the winter season,” Horton says.
But for this specific weather anomaly, Horton thinks Chicago’s lack of snow is by chance: “We have had snow in the U.S. and there were places just south of and north of Chicago who got a ton of snow. In that respect, we’ve gotten lucky.”