Don't Blame Global Warming for Midwest's Mild Winter

SOUTHFIELD, Mich. (WJBK) - It's been a mild winter across the Midwest to say the least. Temperatures in the 50s and the limited snow storms have had people emailing FOX 2 and asking, "why?"

For answers, we turned to Tom Wagner, Cryosphere Program Manager with NASA, to give us an explanation.

Q: Here's what people want to know. Is this global warming?

TW: Probably not. This is probably within the natural variability. If you look at the amount of snowfall we've had this year, it seems like it's a lot less than there's ever been. But in 2006, we actually had less at this point. That doesn't mean that the planet's not warming up. We're certainly losing ice from all the polar regions and all the icy spots around the globe.

Q: But there have been places in the U.S. that have been getting an above average winter as far as snowfall goes, so what do you attribute this variability to?

TW: Now we have enough satellite observations and we've also got the computer models that we can sit down and understand how this all fits together. And the big deal is this -- this year, we have a La Nina year and we have a strongly positive Arctic Oscillation. La Niña means dry air over North America and the Arctic Oscillation means that we have all that cold air staying up north. The upshot of all this is that we wind up with all those snow storms going to places like Alaska, whereas here in the lower 48, we wind up with not a lot of snow.

Q: We've talked a lot about La Niña and El Niño here on FOX 2, but the Arctic Oscillation is a bit different. Give us a primer on what that is.

TW: It's the difference in pressure between the Arctic, the top of the planet, and the mid-lattitudes. When you get high pressure systems up there, you wind up pushing cold air down over North America. This is actually what happened in 2010 and gave us "snowmageddon." We had this strong high pressure system over the Arctic, pushed all this cold air down over the east coast. On top of that, we had an El Niño year which gave us this warm, wet air. You put those two together and you get a lot of snow.

Q: So is winter going to come back and slap us in the face during February and March? Or can we expect this pretty much the whole way through?

TW: Good question. You know, when you have a positive Arctic Oscillation, you can wind up with some real variations in the position of the jet stream and the position of that arctic air. So it's anyone's guess at this point.