Massive Ice Chunk Drifts Toward Canada
Last week, an iceberg four times the size of Manhattan broke off Greenland's Petermann Glacier. The ice island is now drifting south through the Nares Strait between Greenland and Canada. Experts aren't sure whether it will make it all the way to the Atlantic and what damage it might cause on its way. Michele Norris talks with Jason Box, associate professor at The Ohio State University.
MICHELE NORRIS, host:
Researchers are tracking a massive chunk of ice four times the size of Manhattan. It has broken away from Greenland's Petermann Glacier. The giant island of ice is now drifting south toward Canada. This is the biggest arctic glacier break since scientists began monitoring them 50 years ago.
One of the scientists keeping watch is Jason Box, a professor of geography at the Ohio State University. He is a frequent visitor to the Greenland ice sheet. I asked him what it sounds like when such a big chunk of ice breaks off.
Professor JASON BOX (Geography, Ohio Sate University): Well, a lot of times, it's too windy to hear it. But if you're lucky, the wind's down, and it sounds like a rumbling. Some have likened it to the rushing of water. But what I've heard - it sounds more like a cannon going off.
NORRIS: Why does this happen? Why do these big chunks break off?
Mr. BOX: Well, it's been conventional thought that air temperatures were very important, and they probably are. But we're learning recently that small changes in ocean temperatures are much more important because water contains so much more heat. A small change just increases the melt rates underneath the glacier, and it can melt 100 times faster below the water surface than in the air.
NORRIS: Is there anything that they can do to break it up?
Mr. BOX: Well, I'm aware of some studies. In the past, the military have tried to, you know, torpedo icebergs. But it has very little effect. And tugboats have been unable to move these fragments around, either - because they have a really deep keel. And ocean currents will just drag the tugboats around.
NORRIS: Would they ever run ashore? I mean, could they fuse to land?
Mr. BOX: Yeah, that's conceivable. However, the keels on these things, you know, nine-tenths of the thickness is below water. So they will just run aground before they would impact the shoreline.
NORRIS: Is there a connection between these glacial breaks and the rising temperatures around the globe?
Mr. BOX: Yeah, I think there is a connection, and it's because we observe dramatic increase in the sea surface temperatures at the same time that the sea ice, the frozen seawater around this area has declined significantly during the summer.
And then when we average the 30 widest glaciers in Greenland, they collectively show a very consistent retreat pattern. There are physical processes, like the meltwater ponding on the surface of the glacier that can actually cut down through the ice because water is heavier than ice.
And then it just takes some wind to blow these fragments apart, and I believe that we understand well enough to link this with global warming.
NORRIS: Now, this was not altogether unexpected. People had been predicting that a fairly large island of ice would break off from the Petermann Glacier. Are there other large chunks that could break off from the glacier?
Mr. BOX: Yeah, there's another Manhattan-sized chunk that seems liable to break next because it has this even wider crack, that we call the Big Kahuna. I've got some photos of it. It's an enormous crack. And you know, that could happen this year.
NORRIS: Why do I get the sense that you wake up in the morning, and run to your computer to take a look at this?
Mr. BOX: That's actually true. I'm fairly motivated.
NORRIS: I had a feeling.
(Soundbite of laughter)
Mr. BOX: Well, it is very exciting to observe these enormous changes, and it's relatively easy these days - with computers and the Internet. I can pull up a three-hour-old image of the area, and that's what we've been doing this summer, waiting for this to happen. And it's just, you know, kind of thrilling in an ominous way when something like this happens. But we could see it coming; we were just waiting for it.
NORRIS: Professor Box, thanks for your time.
Mr. BOX: Thank you.
NORRIS: That was Jason Box, an associate professor at the Ohio State University.
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