Anybody fancy a swim? This winter has been exceptionally warm, which has a lot of people worried – is global warming happening faster than we thought?
While we’re all for people switching to more energy efficient HVAC equipment, we don’t think there’s any cause for alarm – the wacky temperatures are being caused by totally natural, if not unusual, weather patterns. Here’s what’s going on:
So why is it so warm?
According to Scientific American, the primary cause of this warm winter is an atmospheric pressure pattern called the Arctic Oscillation, a pressure pattern that circles the high Northern Hemisphere. The lower edge of the Arctic Oscillation is called the North Atlantic Oscillation (NAO). Together, the two pressure patterns influence the path and strength of the jet stream, which is an air current that flows west to east across the northern latitudes of the US, Europe and Asia and basically stops cold Arctic air from drifting far south. This year, that jet stream has been much straighter and much more north than usual, meaning that cold air wasn’t able to get down to us. As a result, warm southern air was able to prevail over the entire US, preventing cold fronts from coming down from the north and clashing with warm fronts that would create the large snow and rainstorms. The jet stream has been stuck straight and north for pretty much the entire winter, creating the warmest conditions since weather tracking began in 1865!
The funny thing is, last winter was the exact opposite! Remember all that snow we had? Last year, that NAO had some of the LOWEST pressures ever observed, which allowed the jet stream to move south and stay there. According to Jeffrey Masters, a meteorologist who runs the Weather Underground, “the December Arctic Oscillation index has fluctuated wildly over the past six years, with the two most extreme positive and two most extreme negative values on record.”
So why is this happening now? Meteorologists aren’t sure. Some think it’s a result of the loss of Arctic sea ice caused by global warming. Others are less concerned, blaming the weird weather patterns on sunspot activity, which was very low in December 2010 and very high in December 2011.
Should you be worried?
So should you be concerned about the warm weather? Probably not. Remember – we’ve still got a couple more weeks of winter to go, and scientists expect the temperatures to drop pretty soon (it’s not too late to have furnace repair in Maryland!).
In the meantime, you can head up to Cordova or Valdez, Alaska if you want snow – the two towns are buried under almost 20 ft of snow, with more on the way!