Monitoring a Massive Antarctica Ice Collapse
ALISON STEWART, host:
Just imagine what it sounded like when the Wilkins Ice Shelf cracked. Was it a creak? A crack? A moan? As 5,282 square miles began to shear off, leaving a 200-foot wide fissure? It's still hanging on to the rest of Antarctica, but just barely, according to our next guest, who 15 years ago predicted this could happen. David Vaughn is the principle investigator for British Antarctic Survey Core Program. He specializes in glacial retreat, and he's on the line from Cambridge, England. Thank you, sir, for being with us.
Mr. DAVID VAUGHN (Investigator, British Antarctic Survey Core Program): I'm very happy to be here.
STEWART: First, I want to get some basics. First, explain to me what an ice shelf is, and specifically the kind we're talking about, this Wilkins Ice Shelf.
Mr. VAUGHN: Yeah, an ice shelf is something that's a piece of ice that's floating in the water, and in some cases, the ice shelves are just sort of where glaciers have flowed down towards the sea and then managed to go afloat without breaking up. In other areas, and this is more Wilkins Ice Shelf, the snow accumulates on the ice shelf itself, so there isn't - this one isn't fed by big glaciers coming off the continent. But the ice is fresh-water ice. It's derived from snowfall and it is quite a permanent feature. We expect not to see these things change very often.
STEWART: So, when did scientists first realize that something was amiss?
Mr. VAUGHN: About February the 28th, we saw some signs of change, or rather Ted Scambos from the National Snow and Ice Data Center in Colorado there in the U.S., noted some change and he alerted us to it - many scientists across the world, and we started - we realized that we had an aircraft still in the Antarctic. The winter's just starting in the Antarctic at the moment, but we managed to get an aircraft to fly over, and we got some video footage of things actually happening.
STEWART: Now, when you looked at that video footage, what did you see? What did you say?
Mr. VAUGHN: Well, we kind of saw what we expected to see. We have - the satellite images give you this sort of overhead, downward-looking view. Things are that much more impressive when they're in full color and you see them from the side, when the aircraft flying down a chasm between two large icebergs, between two fractures in the ice. So, things are that much more graphic, it really brings it home to you, the scale of what's really happening down there.
STEWART: It really very much is like a canyon now that has been created.
Mr. VAUGHN: One of the main features is a canyon, but actually, one of the more interesting features for the scientists is the rubble of sort of house-sized icebergs, which we consider to be fairly small icebergs, being produced. Essentially, a big iceberg carved off Wilkins Ice Shelf, and the stress that remained in the ice sheet, ice shelf, broke it up and produced this enormous armada of small icebergs, and that's the interesting point for us.
STEWART: Why is that the interesting point?
Mr. VAUGHN: Because it tells us about how ice responds to climate change. It tells us a little bit about the sensitivity of these ice shelves to climate warming. We know that the climate in this area has been warming now for around 50 years at a very rapid rate, and with that was the basis of the prediction back in 1993 that this part of Wilkins Ice Shelf would be vulnerable to climate change.
We got that much right, but what we didn't get right was the speed at which it would happen, the sensitivity of the system to change, and I think that's the lesson that we have to learn from the events that have gone on in the last few weeks.
STEWART: You brought up a couple of interesting points and I want to break them out. The first is this idea of what exactly to pin this on, we'll say. Global warming, on climate change, whether or not this is big news. I've been all over the blogosphere this morning and there's been intense debate back and forth about whether are we blaming this on global warming? Is there global warming? Should we be using the term "climate change"? One had a very non-scientific poll, very non-scientific, but the majority of people on this pool said, hey, this is just part of the natural cycle of nature.
Mr. VAUGHN: We don't know how long Wilkins Ice Shelf has been there. I certainly know that it's been relatively unchanging for most of the 20th century. Look back at the old expedition reports, back to the beginning of the 20th century, and it hasn't changed much over that hundred years. So, on that time scale, this is an unusual event. But if we look at some of the other ice shelves around the Antarctic Peninsula, we know that those ice shelves, before they retreated in the late '90s, early 2000s, they'd been there for 10,000 years.
So I think it's fair to say that this is not part of some natural cycle that comes and goes every couple of centuries. What we're seeing is a very unusual event. Now, the climate change on the Antarctic Peninsula is much more rapid than global warming, and it's quite different to what's going on on the rest of the Antarctic ice sheet, where climate change is actually very slow - we don't see very strong evidence of climate change. But on the Antarctic Peninsula, the climate really, clearly is warming.
All of the stations we have that collect temperature data tell us that it's warming at a very rapid rate. The big question, the difficult question is saying, well, is this area of highly magnified climate warming is - does it have its root cause in the global warming, the increase in temperature due of emissions of greenhouse gases? And that's actually a very hard question. But as they say, you know, this hasn't - the temperatures on the Antarctic Peninsula haven't gotten to this height in the last 10,000 years, and I think that's a very good piece of indication that this is really is an unusual event.
STEWART: Before I let you go, you mentioned briefly that you had predicted this 15 years earlier. What led you to your prediction?
Mr. VAUGHN: Well, we - really this is only one in a long line of ice shelf retreats that we've been monitoring. Wilkins is the biggest ice shelf to have been hit so far, but we have ten others that have been showing signs of retreating in the past. I think it was really a very simple minded extrapolation that led me to make that prediction. It wasn't rocket science, if you like. But it clearly wasn't good enough because the time scale we predicted at that time weren't really good enough. It happened twice as fast as we expected.
STEWART: David Vaughn is the principle investigator for the British Antarctic Survey Corps Program. Thanks for being with us, sir.
Mr. VAUGHN: You're very welcome.
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