The real reason this winter was so warm
April showers are supposed to bring May flowers. This year, however, it seems that the flowers have come a bit early. An unseasonably warm winter has brought mild temperatures, but where did the snow go?
Sure, not having to clean a foot of snow off the car is probably a nice change of pace, but on average, Columbus experiences 28 inches of snow per year, according to the National Oceanic and Atmospheric Administration (NOAA) website. This past winter, however, the Columbus area received nowhere near that amount. It might be easy to blame global warming and forget about it, but there are other scientific factors that have made this one of the warmest winters on record.
According to the NOAA website, 95 percent of the United States had below average snowfall, which is the largest percentage in history.Rainfall, however, poured in. Columbus had the wettest year on record in 2011, but only a small amount came down as snow.
“It has to do with the jet stream,” Terry Lahm, associate provost and associate vice president for academic and student affairs, said. The jet stream is like a river of air that moves weather from west to east, Lahm said.
The jet stream is located in the upper atmosphere of the northern hemisphere, and acts as a barrier between high and low pressure areas.High and low pressure air control wind and weather around the globe, with high pressure bringing fair weather and clear skies and low pressure bringing clouds, precipitation and strong winds.
The jet stream can dip south, which brings colder weather and more snow, or it can move north, which brings more temperate weather. This past winter, the jet stream was more northern than usual, which allowed Columbus to keep temperatures higher than normal. In essence, all the cold air near the North Pole was kept to the north.
“[The jet stream] kind of represents a wall, if you will,” Lahm said. “It’s keeping that cold air away from us.”
“A strong jet stream that flows in a somewhat straight line from west to east, with few southward dips, prevents cold arctic air from drifting south,” Mark Fischetti reported in his Scientific American article “Jet lag: What’s Causing One of the Driest, Warmest Winters in History?”
The jet stream brings the colder air down and it mixes with the warmer air which causes all the snow, Lahm said. The cold air hasn’t come down, but the wamer, moist air is still here, which is why we still had all the rain.
The Arctic Oscillation, the at mospheric pressure pattern that controls the jet stream, has been keeping the jet stream in a straight line. “Meteorologists are not certain what causes the oscillations to vary so dramatically,” Fischetti reported.
So this is not all an effect of global warming?
“Weather is a short term oscillation in the atmosphere,” Lahm said. “When you talk about climate change, you talk about these long-term oscillations. In the end, you have to average all of that out, and see ‘do you come up with that overall, are we still getting warmer?’ And the answer is yes.”
“There’s nothing to say that next winter might be a very heavy snow winter, and yet, we still are experiencing global warming, even next year,” Lahm said.
The increase in greenhouse gases, such as Carbon Dioxide, Methane and CFCs, has contributed to global warming, Lahm said. The levels of greenhouse gases are the highest they have been in 625,000 years. “We see the average temperature still going up.”
“The global temperature has increased more than one degree Fahrenheit since 1900,” reported David Biello in his Scientific American article “The New Normal?: Average Global Temperatures Continue to Rise.”
Biello reported that NOAA predicts heat waves will become more frequent and intense as the 21st century continues.
