Since early December, Madison's weather outlook has been pretty bleak: a daily dose of brutal cold.
Local conservatives have found a silver lining. What better way to combat the scientific consensus that global warming is indeed occurring than to point out the window?
“THANKS TO #GlobalWarming, Madison experiences 11th COLDEST winter on record,” reads a sarcastic March 3 tweet from conservative radio host Vicki McKenna.
Steve Vavrus, a senior scientist with the UW Center for Climatic Research, concedes that it’s been a bear of a winter – around Wisconsin, anyway.
“Certainly if you live around here it’s the severity of the winter that’s on your mind,” he says. “But we really are the outliers. This has been a very warm winter, globally speaking.”
In fact, Vavrus is looking at the possibility that some of our local winter woes may be happening because of global warming.
Vavrus isn’t mired in the political back-and-forth over climate change. He mainly looks at the effects of a phenomenon that nearly every other credible scientist agrees is fact.
He agreed to spend a few minutes talking about his observations of this winter.
Capital Times: So in terms of cold, how much of an outlier is Wisconsin?
Steve Vavrus: If you interviewed folks in Alaska they’d be saying how incredibly warm this winter’s been. Or folks in Europe, how mild it’s been there. The most telling statistic I think in terms of global climate change is that December was the third warmest, globally, on record. January was the fourth warmest, globally, on record. We don’t have the numbers yet for February, but December and January at least were two of the warmest months on record, globally. So the fact that we here in Wisconsin have been shivering for three months shows what an outlier we’ve been in the big picture
Is the notorious polar vortex that’s been nipping at us for three months the result of global warming?
This is an idea that I’ve been working on, actually, with my colleague Jennifer Frances at Rutgers. We published a paper a couple of years ago that suggested that the faster warming of the arctic relative to the rest of the world could have some impacts, affecting atmospheric circulation and affecting the jet stream. And one of the ways that it might do so is by slowing the jet stream winds and producing more of a meandering circulation which would be favorable for more north-south transport of air. That would include transporting of cold arctic air to our area. So in that sense this winter is consistent with our idea, but we haven’t done enough analysis to know if the warming arctic this current winter is directly a factor.
I know some people who, if they have to go through this again, are going south. Is this the new normal?
Next winter we might be in the warm part and somebody else might be in the cold. This has happened in recent winters. Last winter Europe was really, really cold. And a couple of winters ago we were really, really warm. So there’s certainly a lot of year-to-year variability. But if the arctic is affecting the jet stream in ways that we think it probably is, then I would suspect that there’s going to be a tendency for more variability from winter to winter.
The Great Lakes have been frozen over way more than normal. How does that play in?
A couple of ways. One is that if you replace this relatively warm surface with cold ice cover then it’s much easier for the surface of the lake to get really, really cold. When it’s open water it can’t get below the freezing point. But once you get a sheet of ice on top then it can drop to just about the ambient air temperature. So that’s one way that areas near the lake can be colder when there’s a lot more ice cover than usual. And the other way is that by covering the warm, moist lake surface with ice, we’ve choked off the source of lake effect snowfall. And so normally when we get these cold air outbreaks, you’d expect places downstream of the Great Lakes to get dumped on with heavy snowfall, but if the lakes are frozen, that doesn’t happen.
Is this jet stream abnormality going to persist? That is, are we going to keep getting nailed with colder-than-usual air through the spring and summer?
There’s no reason to think, in my opinion, that a cold winter like we’ve had will necessarily translate into a cold spring. Certainly the beginning of March looks cold. We already are feeling it. But these atmospheric patterns can shift suddenly and dramatically. So nobody really knows what April, for instance, will look like. The one caveat is we have a lot of snow to melt off right now, so even if we start to get some warmer air moving into our area, a lot of the energy is going to be used to melt the snow cover first before it really rises to temperature. But once we lose the snow pack, which could certainly happen this month, then I think all bets are off. I don’t think that there’s too much persistence from one season to another.
Naysayers sometimes concede that global warming is occurring, but they deny that human activity plays a part.
We think it’s very likely that the majority of the warming trend is caused by humans. But it’s impossible for us to know what the global temperature would be, or what the temperature in Wisconsin would be, if it weren’t for the human-induced emissions. We can look at various things — look at past temperature records, look at climate models and so forth — and say that it’s very unlikely that this warming trend is completely natural. All we know is the fact that we’ve had something like 347 consecutive months above normal in global temperature going back to 1985.
Do you ever confront climate change deniers when you’re presenting your data?
There are a few outliers in my field, but they are very, very few. When I give scientific talks nobody questions the concept of global warming, greenhouse effect and so on. When I talk to the public it occasionally comes up. Occasionally if there’s an article published that has me quoted, if you look at the bottom — at the comments of readers — there are a few people who are obviously resistant to the idea of human-induced climate change.
There’s a lot of talk about tackling global warming, but greenhouse emissions continue to rise, correct?
Globally that’s true. There’s been some improvement in this country recently, in large part because of our shift toward natural gas rather than coal. But globally emissions continue to rise.
Right, because while we’ve been talking there’s probably been two coal-fired plants that have come online in China.
Yeah, that’s a big issue. We have made some progress in the U.S., but we’re still such a huge contributor per capita. China has emerged recently and India has increased, too. These are global problems that have to be tackled on a global scale.