Global-warming deniers are happy that there’s a cold snap in the midwest this week because they think it disproves global warming. Does it?
Snow and ice are disappearing from the Arctic region at unprecedented rates, leaving behind relatively warmer open water, which is much less reflective to incoming sunlight than ice. That, among other factors, is causing the northern polar region of our planet to warm at a faster rate than the rest of the northern hemisphere. (And, just to state the obvious, global warming describes a global trend toward warmer temperatures, which doesn’t preclude occasional cold-weather extremes.)
Since the difference in temperature between the Arctic and the mid-latitudes helps drive the jet stream (which, in turn, drives most US weather patterns), if that temperature difference decreases, it stands to reason that the jet stream’s winds will slow down. Why does this matter?
Well, atmospheric theory predicts that a slower jet stream will produce wavier and more sluggish weather patterns, in turn leading to more frequent extreme weather. And, turns out, that’s exactly what we’ve been seeing in recent years. Superstorm Sandy’s uncharacteristic left hook into the New Jersey coast in 2012 was one such example of an extremely anomalous jet stream blocking pattern.
When these exceptionally wavy jet stream patterns occur mid-winter, it’s a recipe for cold air to get sucked southwards. This week, that’s happening in spectacular fashion.