Researcher Explains Greenland's Melting Ice
ROBERT SIEGEL, Host:
From NPR News this is ALL THINGS CONSIDERED. I'm Robert Siegel.
MICHELE NORRIS, Host:
And I'm Michele Norris. The ice in Greenland is melting faster than we thought. That's the finding of two scientists, one from the Jet Propulsion Lab and one from the University of Kansas. They have found glaciers in Greenland are melting and draining into the ocean at a much faster rate than previously believed. That's taking place as the temperature around Greenland is rising. Evidently, the more temperate Greenland climate is not news to the people in Greenland.
SIEGEL: Joining us to talk about this first is Pannir Kanagaratnam who is in Lawrence, Kansas where's at the University's Center for Remote Sensing of Ice Sheets. And he's one of the researchers who did this study. Professor Kanagaratnam, how fast did scientists think Greenland's ice sheet was melting before your study and how fast do you say it's melting?
PANNIR KANAGARATNAM: In 1996 they were saying there were 22 cubic miles flowing into the ocean. Our study found in 2005 it's 54 cubic miles. So it's almost more than doubled what the previous measurement showed.
SIEGEL: How do you go about measuring how many cubic miles of ice melt in a given year?
KANAGARATNAM: We take satellite measurements as well as ice thickness measurements. And the satellite measurements basically takes a photograph of the ice location over time. So we can track the futures and see how the ice is moving. And the thickness of the ice sheet gives the, basically the volume of the ice that's being discharged into the ocean.
SIEGEL: Over the past 10 years would we see a steady progression of a rise in the speed of melting? Or have there been fast years and slow years?
KANAGARATNAM: It's been steadily accelerated.
SIEGEL: Steadily accelerating during that time?
SIEGEL: How do you know what the cause of that acceleration is?
KANAGARATNAM: We are guessing at this point that it's the increased temperature. Well, we know that definitely the temperature's increased and the melted water is seeping into the bed of the ice and that's facilitating faster flow of the ice sheet into the oceans.
SIEGEL: But when you say that temperatures have been increasing, how much have they increased?
KANAGARATNAM: There was one particular location that we measured that's increased by three degrees Celsius over a 12-year period.
SIEGEL: Three degrees Celsius.
SIEGEL: That would be about five degrees Fahrenheit.
SIEGEL: Well, joining us now from Thule Air Base in Greenland is Jack Stevens, who works at a weather station there. And Mr. Stevens is the warming in Greenland over the past few years evident to you and other people there?
STEVENS: Well, anecdotally, yes there have been some increases that people notice. The one thing that we've noticed is that since the year 2000 we've experienced a sudden appearance of mosquitoes and flies in the summertime for a few weeks. And in the past this would never be observed, but then suddenly it became a problem because of the, the warming allowed them to generate more numbers.
In addition to that, we have reports from the surrounding areas, the Inuit hunters who live in the surrounding areas, they have problems that they didn't have before with open water in areas where they normally do their dog sledging, their hunting. And also we've noticed that the sea ice tends to break up one or two weeks earlier on average than former times. And in general the summers are between one and two degrees Celsius warmer than they were before.
SIEGEL: Now, as you say there's a lot of anecdotal evidence there. Pretty powerful anecdotal evidence I might say. But does it...
STEVENS: It's very noticeable. In fact, for us here at Thule Air Base, I guess the most noticeable is the appearance of the mosquitoes. Especially because before, I mean, you would walk out in the summertime and there would never be a problem with it, but now from two to four weeks in the summer you have to have bug spray or some other kind of protection or else you can have a problem.
SIEGEL: Well, Professor Kanagaratnam, what's you sense of what has happened in Greenland in terms of surface temperatures over the past decade?
KANAGARATNAM: I've been making ice thickness measurements since 1998, and in 1998 when we were taking measurements I do notice many water puddles to the north of 66 degrees. But this year when I went I noticed considerable amounts of water puddles appearing further north of Greenland, which shows that temperatures are rising there as well.
SIEGEL: One of the ideas that you're up against when you describe a more rapid melting and a rise in the oceans is, I think people sometimes have a sense of confidences that the earth is just too big, that the oceans are too large for changes, even measurable to make a big difference. But I guess you would say not.
KANAGARATNAM: That's right. Even within the short period of time when we have been studying this ice sheet movement, we've noticed lots of changes. So, it is quite a dynamic operation taking place on those ice sheets, and further monitoring of those ice sheets will give us a lot of clue of what's going to happen in the future.
SIEGEL: Well, Professor Pannir Kanagaratnam in Lawrence, Kansas and Jack Stevens at Thule Air Base in Greenland, thanks to both of you for talking with us today.
STEVENS: Thank you.
KANAGARATNAM: Thank you very much.