Dr. Mark Serreze, director of the National Snow and Ice Data Center (NSIDC), a federally-supported research unit at the University of Colorado, told CNSNews.com that the hypothesis is that the decline in Arctic sea ice in recent years has created more open water in the Arctic in summertime, and that this open water absorbs more heat during the summer than the former icepack did, then releases that heat during the winter months, warming the Arctic itself, while pushing cold Arctic air down over the eastern United States and Europe.
“Here’s what happens and here’s what a lot of people get really screwed up on, and it’s straightforward,” Serreze told CNSNews.com. “All right, so it’s getting warmer, and what is happening is that we’re not growing as much ice in winter as we used to be, but we’re melting a heck of a lot more in the summer than we used to. “So, now what happens is that if we look at the end of summer, end of the melt season in the Arctic—September, say, specifically September--what you find is that there’s much, much more open water than there used to be,” said Serreze. “But what has happened is because that open water is very dark it’s been absorbing a lot of solar heat through the summer."
“So now you’ve got this ocean with all this heat in it that it didn’t used to have. Autumn comes, the sun sets in the Arctic, that heat gets released back to the atmosphere,” he said. “And so what’s happening is the atmosphere gets warmed, because the ocean is losing its heat back to the atmosphere. That’s why you get this big warming in the Arctic in the autumn and through the winter, because it’s releasing that heat back. “So you say it’s related to the ice melt. Yes, it is,” said Serreze. “But actually there’s a seasonal lag to it. It’s actually, the ice is melting in summer, exposing all this dark open ocean, picking up all this heat, and, then, autumn comes, the sun sets, that heat’s got to go back to the atmosphere, and that’s what it does. And that greatly warms up the Arctic relative to where it used to be--in other words, relative to, say, where we were 30 years ago. And what’s happening is that that is starting to change the sort of basic temperature gradients in the atmosphere that I talked about before.
“And so if you do that, the thinking is that could actually let this cold air in the Arctic kind of start to spill south,” said Serreze. “Now you say, ‘Well, hasn’t the air been warmed?’ Yes, it has, but it’s still cold air, though. “But that’s the thinking,” Serreze explained. “The thinking is that, to put it in another way, we’ve put now a heat source in the Arctic that there didn’t used to be. And if we do that, the thinking is the atmosphere—the circulation of the atmosphere—responds to that. It feels that heating and responds to that. And one possible outcome of that is you get this sort of pattern that you’re seeing here for the last couple winters, that you’ve had cold and snowy over the eastern U.S., especially over Europe, but at the same time this extremely warm Arctic." “I mean that’s basically it in a nutshell,” said Serreze.
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