Carbon dioxide emissions are causing temperatures to rise and that’s making Greenland glaciers melt at rates faster than previously expected. Living on Earth host Steve Curwood talks with Richard Alley, professor of geosciences at Penn State University, about how melting ice sheets may affect sea levels and global coastlines.
CURWOOD: It's Living on Earth. I'm Steve Curwood, at the United Nations Climate Change Conference in Montreal.
CURWOOD: Much of the buzz in the hallways at this meeting is about recent scientific studies on the effects of global warming, especially in the Arctic regions. The permafrost of the far North is thawing. In just a few decades, 30 percent of polar sea ice has turned liquid and the two mile thick ice cap that’s covered Greenland for thousands of years is melting away at its edges.
All this melting may be slowing down the Gulf Stream that sends warm water and mild weather from the tropics up the East Coast of North America and then east to Europe. And if the Gulf Stream slows down much further, the Northeastern United States and western Europe could get much colder - a paradoxical response to a warming world.
But there’s a far more profound threat on the horizon: If all of Greenland’s ice sheet should melt, sea levels around the world would rise about 23 feet, and entire portions of populated areas from South Florida to Bangladesh would disappear under water.
Recent observations by a team led by Richard Alley at Penn State University show that Greenland’s ice caps are, in fact, already melting faster than expected. His findings are published in the October issue of the journal Science. So let me ask you, Richard, just how fast is all this ice melting?
ALLEY: Greenland looks like it is shrinking a little bit, and contributed global to sea level it’s somewhere vaguely in the neighborhood of a quarter of a millimeter a year. So that’s about an inch per century. So right now it’s not huge for sea level.
Right there on the coast, you know, that’s a lot of melt going on, and if you go and look at the little glaciers that sit in the mountains along the coast next to the big ice sheet, they are all pulling back very rapidly and you can see the changes happening. So far, though, for the global ocean it’s not a really big thing yet.
CURWOOD: So, what is the concern here? If it’s really, what, an inch or something over a century, that’s certainly not a very big number to be worried about. Why are so many folks concerned about Greenland ice at this point?
ALLEY: The warming that’s happened so far is very small compared to the warming we expect if we go ahead and burn all the fossil fuels. So, so far the warming is something like a degree Fahrenheit, and that’s taken most of a century to happen. And that’s smaller than the difference between last winter and this winter and next winter, just from the bouncing noise of climate. You really sort of have to be paying attention to see that the climate is changing.
Our expectation, if we go ahead over the next centuries and get really serious about digging up all the coal in West Virginia and Pennsylvania and China and burning that, then you start looking at changes of ten degrees, 15 degrees, possibly even more depending on some things we don’t quite know. And then the change starts getting big enough that you look at that big ice cube on Greenland and you get nervous.
CURWOOD: So, just how fast would that big ice cube on Greenland, as you have put it, how fast would it melt under the present trend of using fossil fuels?
ALLEY: If we go ahead and we burn it all, it’s possible it could melt in many centuries, but less than a millennium. This is not a prediction; we’re not sure. There’s some things that we need to work out yet.
CURWOOD: At this point, the official international scientific assessment, the Intergovernmental Panel on Climate Change, I guess the last full assessment was issued in 2001, talks about someplace on the scale of a half a meter or so of sea level rise over the next hundred years. From your research about Greenland, how would you adjust that prediction, if at all?
ALLEY: I have the good fortune to be helping work on one of the chapters in the next assessment. The previous assessment, the 2001 assessment, suggested that the sea level rise coming in this century, over the next 100 years, would come almost entirely from melting of mountain glaciers; and it would come from expansion of the ocean water itself as it gets warmer, and that a little bit of melting from Greenland would be balanced by more snowfall in Antarctica, because Antarctica’s so cold that it wouldn’t be melting but warmer air will carry more moisture up onto the ice sheet.
So the previous assessment said we’ve got 100 years before the ice sheets start to contribute. And there’s still a little more uncertainty than we want, but it sort of looks like the ice sheets are already contributing. And so it looks like the ice sheets may be 100 years ahead of schedule at this point. If that proves to be true as we come over the next months and years, it’s certainly a matter of great concern to me.
CURWOOD: Let’s talk about the human impact here. If all this is going on, if this is a result of humans adding carbon dioxide to the atmosphere, how quickly can we reverse that?
ALLEY: Clearly, we humans can do almost anything we want to if we really, seriously want to. But most of the people that are going to listen to this are going to get in a car during the day and go somewhere, and they’re not going to walk home. And some of them are going to get on a plane and fly somewhere, and they’re not going to walk home. And so, changing that likely would take some time. There are credible estimates, smart people thinking about this very deeply and carefully, that think that a few decades of serious research would be enough to tell us how to fix this problem without screwing up the economy and without making anybody walk home from their plane trip.
CURWOOD: Do we have a few decades to figure this out?
ALLEY: I think that we have decades to fix this. But I’m really worried if we wait centuries that we will end up with a really different world; a world that doesn’t have a Greenland ice sheet, a world that doesn’t have New Orleans or the southern part of Florida or a whole bunch of other things. And so if we actually get the wherewithal to use alternate fuels to recapture CO2 from the air or from power plants, it’s quite reasonable that we can get there with a fix by being smart.
CURWOOD: Richard Alley is a professor of geosciences at Penn State University. When do you head back to the ice, sir?
ALLEY: I hope to be in a freezer next summer working on some of the ice coming home from Antarctica, but when I’ll actually get there, we’ll see.
CURWOOD: Thank you so much.
ALLEY: It’s a pleasure talking to you. Thank you.
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