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Global Warming's Impact on Glaciers

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Global Warming's Impact on Glaciers

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Global Warming's Impact on Glaciers

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We're going to take a short break and switch gears and come back and talk about glaciers, all the melting glaciers around the world. If you want fast questions about that, we have a couple of experts with us, and one explorer's been to many of them, so stay with us; we'll be right back.

I'm Ira Flatow; this is TALK OF THE NATION, SCIENCE FRIDAY, from NPR News.

(Soundbite of music)

FLATOW: You're listening to TALK OF THE NATION'S SCIENCE FRIDAY. I'm Ira Flatow. Glaciologist Lonnie Thompson has two pictures of Mount Kilimanjaro. In fact, if you go to our website at Sciencefriday.com, you can see those pictures. The first one is taken in 1912 and it shows the snow-covered peak made famous by Hemmingway.

The second one is shot, many years later, in the year 2000, and it shows a really dramatically different mountain. The snow and the ice have receded and there's this rocky terrain with just scattered sheets of ice. Five years ago, Dr. Thompson estimated that at the current rate of retreat, the snows of Kilimanjaro would be gone by 2020. He is just back from his most recent trip to the mountain and he stands by this earlier prediction and says there is a noticeable decline in the ice ever since he's been there, even since the 2000 trip.

Mount Kilimanjaro is really the poster child for global warming. It is a stark reminder that glaciers all over the world from Antarctica to Alaska are retreating, melting, as the Earth warms. And this hour we're going to talk glaciers with Lonnie Thompson, who has gone on more than 50 expeditions.

And Mark Bowen, a writer and accomplished climber who went with Dr. Thompson to Kilimanjaro and to Sajama, which is in Bolivia. And he writes about the expeditions in his new book, Thin Ice, and if you'd like to talk glaciers, global warming with us, our number is 1-800-989-8255, 1-800-989-TALK. Let me introduce my quests.

Lonnie Thompson is a distinguished university professor and senior research scientist in the Burt Polar Research Center at the Ohio State University in Columbus and he joins us today from WOSU in Columbus.

Welcome back to the program.

Dr. LONNIE THOMPSON (Distinguished University Professor & Senior Research Scientist, Byrd Polar Research Center the Ohio State University: Thank you, Ira.

FLATOW: Good to have you back.

Mark Bowen is a physicist, a rock climber, a photographer and author of Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains. And he joins us today from WBUR in Boston.

Welcome to the program, Dr. Bowen.

Dr. MARK BOWEN (Author, "Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains"): Thanks, Ira, nice to meet you.

FLATOW: You're welcome.

Tell us, Lonnie, what your reaction was. Here you were there in 2000, you're back five years later, was it really a dramatic difference in just those five years, or just a slight difference?

Dr. THOMPSON: No, it's quite a dramatic difference. You can actually see it; see the change from the base of the mountain looking up from Oshe(ph).

FLATOW: Mm hmmm.

Dr. THOMPSON: Actually rocks, bare spots that didn't exist in 2000. And then from the aerial photographs that we had flown just a few weeks ago, it's very obvious when you compare the ones from 2000 to those from January; the difference is tremendous.

FLATOW: Is it going to beat your prediction of 2020 or do you think it will be right on?

Dr. THOMPSON: Well, it's certainly on track. My guess, in just doing a visual comparison between these aerial photographs is that some of the glaciers like Fiertwanger(ph), which is in a crater, is probably lost somewhere between 30 to 40 percent of its mass since 2000. That would argue that maybe there's an acceleration taking place. But we'll know better when we complete the new map and can compare it directly with the one from 2000.

FLATOW: Mm hmmm. Let's talk about your work as a scientist and drilling down into the ice to get ice cores. How far do you drill down, and what can you learn from pulling all that ice out?

Dr. THOMPSON: The depth we drill is determined by the site, the thickness of the ice. We've drilled, you know, for example, in Southeast Alaska on Mount Bona-Churchill to 460 meters depth.

And the length of record that's archived in these glaciers, these mountain glaciers in particular, really depends on the location; not so much on the thickness, but on the temperature of the ice at the ice/bedrock contact.

FLATOW: Mm hmmm.

Dr. THOMPSON: If it's frozen to the bed, time cannot be removed, so on some of these glaciers out of Tibet and down in the Andes we can get quite long records spanning over 100,000 years of climate history from these areas. And in the ice itself, the places we drill are the highest mountains on Earth. And the reason we do that is it's where it's the coldest, you have less disruption of the archive. And in these areas every year you get snowfall and that snowfall is preserved. And by taking a drilling system and going into these sites, we can recover that archive.

And in many cases where there's a very marked wet and dry season, which is true for much of the tropics, you can actually see the annual layers in the cores...

FLATOW: Mm hmmm.

Dr. THOMPSON: ...when you're drilling them. And it gives us a very high resolution record of the climate of the past. And when we bring these cores back, they're about a meter in length and about 11 centimeters, four inches in diameters. And we measure a number of different parameters. We look at isotopes, stable isotopes of oxygen and hydrogen which makes up water molecules as a proxy for the temperature of the past, being an indication of temperature. You can look at those annual layer thicknesses and you get a history of precipitation. And there are not too many archives on earth that allow us to reconstruct the past variations in precipitation.

FLATOW: Mm hmmm.

Dr. THOMPSON: In the ice, anything that's in the atmosphere, everything from volcanic activities, from the ephra(ph), the sulfate from those eruptions to the pollen that comes from vegetation around these ice fields is preserved; and hence, a history can be produced of climate and environmental variations...

FLATOW: Mm hmmm.

Dr. THOMPSON: ...in each of these different sites.

FLATOW: Mark Bowen, in fact that's one of the first things you learned on your expeditions with Lonnie Thompson in the Andes was that it's like reading tree rings.

Dr. BOWEN: Right.

FLATOW: Go ahead.

Dr. BOWEN: I first met Lonnie in 1997 when I was assigned on very short notice to fly off to Bolivia from Boston; I had about five days to get ready for it. And it was while I was, I didn't know anything about climatology or global warming or anything like that, I had a background in science and I'd climbed a few mountains, and it was as I was climbing the mountain that a colleague of Lonnie's name Todd Sours(ph) told me all, a little bit about this stuff, gave me a bit of an introduction...

FLATOW: Mm hmmm.

Dr. BOWEN: ...and he explained that it was a lot like tree rings, just of, as you might core into a tree horizontally, they just go down vertically. And if a few pictures Lonnie has taken...

(Soundbite of laughter)

Dr. BOWEN: ...just show dramatically...

FLATOW: Yeah.

Dr. BOWEN: ...how it's like tree rings.

FLATOW: That's interesting because I would think that as a photographer, you approach a site when you see it through a photographers eyes, the composition, whatever, of anything that you're looking at. Are you struck as much as Lonnie about the retreat of these glaciers?

Dr. BOWEN: Oh absolutely.

FLATOW: And the changes to them?

Dr. BOWEN: Yeah, and as a climber I hear stories, just anecdotal stories from my friends coming from all over the world. In fact, when I first approached a friend of mine named Lindsay Griffin, who lives in Britain and maybe the foremost authority on just what's going on in the mountains around the world, he writes a column for High magazine, or used to. I said, you know, the changes are amazing. I'm hearing all these stories about the mountains. He says, well, that's not news to me. I've known it for 10, 15, 20 years.

FLATOW: Mm hmmm. Do you see more water rushing out from the bottom of some of these glaciers?

Dr. BOWEN: Well, at certain times of the year...

FLATOW: Mm hmmm.

Dr. BOWEN: ...yeah. I mean Lonnie could probably answer that question better than I.

Dr. THOMPSON: Well, you can go to some of these like the Calkia(ph) Ice Cap where we have studied since 1974. And it used to be we'd go down there in the dry season, which is the cold part of the year, and there would be no water coming out from that glacier. In the last 10 years that we've gone down there, there's practically a river coming out by the campsites. And it flows year- round. So you can see dramatic increase in the water coming from many of these glaciers.

FLATOW: I understand that you invented actually, a new way of retrieving high- altitude ice cores. What is that?

Dr. THOMPSON: Well, when we started, we were a bit naïve. We thought we could just bring a drill from Antarctica and a power system and be able to get that up to these high elevation sites. And we first attempted that on this Calkia Ice Cap down in the Andes of Peru, only to find that it was impossible to move such heavy equipment up to those elevations.

So, we had to come up with a new way to recover ice and that meant designing a lightweight portable drill system and also designing new power sources. And we've used photovoltaic cells to provide power for drilling, particularly in the tropics.

And, when you think about it, in these areas you have over half of the earth's atmosphere below you. So these panels actually produce 20 to 30 percent above manufactured specs for power output.

FLATOW: Mm hmmm.

Dr. THOMPSON: I mean it provides an environmentally correct way to recover ice. There's no noise, it's a silent drilling and there's no pollution to the site, so...

Dr. BOWEN: It's an incredibly elegant setup. That was what struck me when I first met Lonnie on the top of this mountain. Just a magnificent place to begin with. I call it an island in the sky.

And Lonnie and his team, by the time, had been doing this, they had their big success on Quelccaya in 1983. I met him in 1987, so that's, you know, 14 years later or something. By that time, they had just worked it out to the purity of a dance. And they knew before the even left Ohio exactly what they were going to do with the ice when they brought it back. They had figured all the details out how not to touch it with anything except rubber gloves.

And here they were working in this magnificent spot where you could see for 300 or 400 miles up and down the spine of the Andes. And it was absolutely silent because of this solar power. So it was just a magnificent setting.

FLATOW: Now, you as a climber have a real appreciation for how these scientists--the effort it must take to go up and down these mountains with the equipment and just to go up into this what you call the Death Zone and work up and down a mountain. You know, it's not something a laboratory bench scientist does on the ground.

Dr. BOWEN: That's right. Lonnie, I think we've calculated almost certainly that he's spent more time above 18,000 feet than any human in history, including, you know, Reinhold Messner and Doug Scott and all the great climbers.

And when I met him on Sohama(ph), I kind of raced up there. I was pretty careful because it literally is deadly to go up too quickly. In fact, a woman died of edema on this very mountain only a month or two after Lonnie left.

But Lonnie and his crew lived up there for 28 days in a row drilling ice cores. It was pretty rough for me, I have to say. I toughed it out for about two days. And I don't know whether it was--I made up some excuse to be able go back down. I pretended that I kind of got, I had everything I needed to know. Maybe I did. But it was cold, too.

And I was just terribly impressed. The other--yes.

FLATOW: Go ahead.

Dr. BOWEN: The other thing about it that I just have to say, George Steinmetz, a fantastic photographer, actually was assigned to this article with me. And he took just fabulous pictures. He has a knack--I mean, I understand that George was really hurting from the altitude up there.

Lonnie and his gang had to actually attend to George for a while. We won't get into the details there. But he still took just superb pictures, one of which is in my book and it shows them sitting in this tiny little snow cave that they lived in for 28 days.

It just captures the essence of the whole thing. And in there I had this, it was a remarkable atmosphere. And I describe it as being kind of monastic. They were very quiet. They weren't the wild and crazy guys that I usually meet on my climbing trips.

And there's something that haunts me about this picture because Lonnie, in particular--I don't know, Lonnie, I'd love to check this out with you a little bit, but he was really at the height of his powers, his intuitive powers right then.

Here he was living under the ice for 28 days, drilling the ice, thinking about it in a very contemplative way. And he said things to me. I was totally naïve just taking down notes about what he was discovering on that mountain.

He was finding things out. He was seeing things that had never been seen in any ice core anywhere in the world before. And he was making these bold predictions about what he was going to find. It turned out to be absolutely true.

He then went off--he was home for only 10 days, left for the Himalayas where his crew lived for 35 days at a location 2,000 feet higher than Sohama, 23,500 feet, and broke the record for high altitude ice coring they had just set on Sohama. I mean, it was astounding.

During those two--during that period, about the following year or so, Lonnie also, he had a number of important realizations, including one that came from the Himalayas. So, I don't know, I think there's something contemplative about it.

And Lonnie mentions this a lot that...

FLATOW: Well, let me ask him about it.

Dr. BOWEN: ...he has some of his best ideas up there.

FLATOW: Let me remind first, everybody, that this is TALK OF THE NATION Science Friday from NPR News. I'm Ira Flatow, talking with Lonnie Thompson and Mark Bowen, author of Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains just published by Henry Holt.

Lonnie, why do you do what you do? Why do you subject your body to, you know, the rigors? What is driving you, I guess is the question I'm asking?

Dr. THOMPSON: Well, I think the--it is just the excitement of discovery, of new things. And we have, over the years, gone to places where other people haven't gone. And if you do that, it almost ensures that you're going to find something that no one has seen before.

I also have a lot of respect for the mountains. And I believe in today's world where we have so many interruptions in our thinking process--I know when I'm at the university, between, you know, the cell phone and the regular phone, the fax, the email, that the time to be able to really think about something gets disrupted.

When you're out in the field in one of these isolated places, I think often you can see things clearer or you can think clearer about things.

FLATOW: 1-800-989-8255. Let's go to Oakland, Connecticut. Tim, hi. Welcome to Science Friday.

TIM (Caller): Hi. Good afternoon.

FLATOW: Hi. Go ahead.

TIM: The question I had was when--are the glaciers solely reacting to climate warming? Or are they actually possibly slowing it down, like ice in a glass of water? And when they're all gone, might we see a rapid increase in temperature?

Prof. THOMPSON: I think that's a very important point to make. When we think about the glaciers and what's happening to them, a lot of heat in today's world is going into melting them, be they the mountain glaciers that we have been studying or the polar ice sheets or the arctic sea ice cover.

So, a lot of heat is being taken up in this process. So, if you think about the glaciers, you know, they're one of the balancing mechanisms that we have for the climate of the earth. And as they become smaller, they are less effective in that.

FLATOW: All right. We're going to have to take a quick break. We'll come back and talk more about glaciers with Lonnie Thompson and Mark Bowen. So, stay with us. We'll be right back after this short break.

I'm Ira Flatow. This is TALK OF THE NATION Science Friday from NPR News.

You're listening to TALK OF THE NATION Science Friday. I'm Ira Flatow. We're talking this hour about melting mountain glaciers with my guests Mark Bowen, physicist and author of Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains, Lonnie Thompson, distinguished university professor, senior research scientist in the Byrd Polar Research Center at Ohio State University in Columbus.

Our number, 1-800-989-8255. Dr. Thompson, is there a place you would like to go that you haven't been able to get to yet?

Dr. THOMPSON: Yes. In your introduction in this program this hour, when you're talking about New Guinea, there's a glacier on, Cartins(ph) glacier located there. It's the only glacier in the center of the warm pool on earth.

And we haven't pursued it because we know there's a lot of melting taking place there. But one of the things that we have thought about is, you know, whether you can interpret a record in today's world using today's techniques is one thing.

But if you were to recover that ice before it disappears, and it will very shortly, maybe 20 years from now we would have the techniques, the technology, the understanding, that we might be able to actually use that archive.

But there are a number of places around the world where I believe that very important records could be obtained from the low latitudes.

FLATOW: Well, why is it that you think that mountain glaciers hold the key to global warming?

Dr. THOMPSON: Well, first of all you have to look at the earth as a whole. If you look at where the surface area of the planet occurs, 50 percent is in the tropics between 30 North and 30 South. And that's where the heat that drives the climate system is absorbed. This is where water vapor is pumped into the earth's climate system.

And it's also the place where we have major climatological phenomena like El Minos and monsoons and monsoon variability that impact people. If you look at the number of people, you know, we've got about 6.5 billion people living on the planet, 70 percent of them live in the tropics.

So, this is a huge area that's really under-represented when we look at our histories, our paleoclimate histories of the past. And it's an area that we know in the last 100 years that climate variability coming out of the tropics impacts the whole earth.

So, it's an area that we need to understand both the natural climate variability and also the human cause for variability.

FLATOW: When you work with an ice core, and we talked about them having layers like tree rings, how far apart are those rings? And how easy is it to separate one ring from the other if you're working on it?

Dr. THOMPSON: Well, again, it depends on the site, the annual accumulation of snow. But for example, on this Quelccaya ice cap, the largest tropical ice cap on earth, there is three meters, 10 feet, of snow every year.

So that's the separation in the layers. So, you can almost look at the weekly changes in such a record. And that archive is annual. I mean, you can see those annual layers back over 1,500 years.

So, in an area like that you get a very high resolution record but usually not as long. Some of the other sites we drill, like in western China, accumulation may be of the order of only 20 centimeters a year.

And you don't get the resolution, the annual resolution, from those records. But what you get is a very long history. And our oldest record comes from the Glee(ph) ice cap in the western Kudo(ph) Mountains covers over 750,000 years.

So there can be really long archives if the accumulation is low and it's very cold.

FLATOW: Mark Bowen, is there a place you would like to go that you haven't gotten to yet?

Dr. BOWEN: Well, I just want to go back down to Peru, actually. I learned so much about Peru writing about Lonnie that I just became totally intrigued with all these cultural transitions that were described by archaeologists as a result of his climate records. It just showed the rise and fall of literally dozens of civilizations. And I just became fascinated with them.

The Quelccaya ice core, Lonnie says, you know, it doesn't go back all that far. But it was used by archaeologists because of its just quartz crystal timing accuracy. It created a small revolution in the understanding of pre-Inca civilizations down there.

And learning about them made me intrigued to do that. I would say also, you know, I have been to Carson's Pyramid, where Lonnie wants to go. I would love to get back there. Lonnie might be the only person from the West who could possibly get there because it's one of the most unstable political situations, and sad political situations on earth. And it's right near this huge American gold mine, which is, you can literally, when you sleep in Carson's base camp you can hear them grinding away at the stones underneath your ears. So he'd better get there fast. The whole mountain might fall down.

FLATOW: 1-800-989-8255. Michael in Plymouth, Wisconsin. Hi, Michael.

MICHAEL (Caller): Yes. Hi, Ira. I've got to tell you, every time I listen to your show I learn so much. Here's my, my question is this. How do you, what's the mechanics of extracting these ice cores? It seems like, you know, I envision a drill going down and kind of destroying it. But I wonder how you get these, you know, long cores out with, you know, in some perfect, you know, some great condition that you can look them? Especially, you know, in these hard to get to areas?

FLATOW: Yes, it's not a drill bit you're going to get it Sears, is it?

MICHAEL: No.

BOWEN: That's for sure. You want me to do that one, Lonnie?

FLATOW: Lonnie, why don't you tell us how you do that?

THOMPSON: Well, I need to point out that I've been very fortunate. We have a wonderful team of people, and that team includes engineers, and we actually design our drills. And we use two different types of drills. One is an electromechanical drill, which physically cuts the core, it cuts the ice, and it retrieves cores of a length of about 1.6 meters.

FLATOW: So is it like a pipe with teeth on it? I guess that's what we're trying to envision, what it looks like.

Dr. THOMPSON: It's a lot like an ice screw. It's a hollow, it's got threads on the outside, and it's hollow on the inside.

FLATOW: Right.

Dr. THOMPSON: And it has a way of holding itself steady in the hole. They're called anti-torque skates. Anyway, it's kind of hard to describe. But he drops it down, he pulls them out one meter at a time. He's just making a little hole in the ice.

MICHAEL: Okay.

Dr. THOMPSON: It's not anything that destroys much. There's some shavings from the coring process that end up on the outside of the screw, but he's just pulling up little core segments, one meter at a time. And he just, over the course of months, works his way to the bottom of a glacier.

MICHAEL: Okay.

FLATOW: All right, thanks for calling. I was wondering also, so I'm glad you asked that question.

MICHAEL: Thank you.

FLATOW: Thank you. And so then you have to get it down the mountain, right?

Dr. THOMPSON: That's the other challenge, particularly in the tropics, is how do you keep it frozen to get it back to the lab? And we've worked different ways to do that, depending on what country we're working in.

But for example, if you're working in Tibet, you have to remember, we move six tons of equipment into the drill site, and when we're finished we bring out ten tons, four tons of ice, frozen ice. And while the ice is being drilled, we have a cave, we dig a cave into the glacier where the cores come out of the drill, they're put into a plastic sleeve and then they're put into a cardboard tube. And they're stored in this cave up until we're finished.

Then we use sleds, they're man-hauled from the drill site to the edge of the glacier. If you're in Tibet, you have to move it from the edge of the glacier down to where the trucks are, down in the valley. And we use yaks to do that. And to give you an example, a yak, you can get two insulated core boxes, you can get six meters of core in each of those boxes, so twelve meters per yak. And we recover five to six hundred meters of core, to give you an idea of the herd that's required to move it down to those trucks.

And then there's a dash across Tibet to the nearest freezer, which happens to be in Lassa, where we can store it until we can arrange the air cargo to move it from Lassa to Beijing, where we clear customs. And then we air cargo it to Chicago, and in then it's trucked in a freezer truck down to the storage facility here at Ohio State University. So sometimes these cores can be in transit for a month from the time they leave the drill site.

Mr. BOWEN: And I should point out that once an airline that shall go unnamed lost some of Lonnie's cores, but he managed to find them. And I would say that, well, Lonnie's colleague, Mary Davis, thinks that actually getting the ice cores off of Galathea was probably the hardest thing they've ever done in their lives.

FLATOW: Wow.

Mr. BOWEN: I mean, the story of how they did that, it ranks with, you know, Shackleton and Scott for what they went through, getting that stuff off there.

FLATOW: That's some story. Yeah

Mr. BOWEN: Driving it across this desert. You know, anyway.

FLATOW: That's interesting. Lonnie, what message do you most want people to take away from your research?

Dr. THOMPSON: I think that what we have strove to do over the years is to build this database, this global database from these ice cores that document natural change and the change in the 20th century, and the documentation of the loss of these glaciers, these archives.

I mean it's, we already know, for example, on the Kilimanjaro, had we waited until 2006, rather than 2000, to drill those cores, we would have lost the only timeline that we had of a recent event, which happened to be the Ivy test, the Chlorine-36 from the thermonuclear bomb test back in 1951, '52, that left a mark on the surface of that glacier. That was 1.8 meters below the surface in 2000. We have lost, on that ice field now, over two and a half meters since 2000, and hence we have lost that timeline that would have gave us a starting point for that climate record.

So this change is real, it's global and we hope that these facts will in some way be able to work their way into national policy and action, that we will have to deal with the issue of a warming world and the impacts of that warming world on water re-supplies and the ability to produce food in different parts of this planet.

BOWEN: And sea level

Dr. THOMPSON: Yeah, and sea level. Yes.

FLATOW: Mark Bowen, do I hear echoes of James Hansen, the NASA climatologist, in your book?

Mr. BOWEN: I would say outside of Lonnie's team, he's probably the most prominent scientist in the book, because in the course of telling the story of Lonnie's career, it was first of all necessary to talk about what's going on in climatology. And then of course the biggest thing happening in climatology right now is global warming. And Jim Hansen has been basically ahead of the pack, making accurate and conservative predictions for 30 years now.

I did a little looking today, and I see that it was in 1981 that he first predicted something that he said just, you know, in December, which got him in a lot of trouble, but he's not really changing his tune. And I think both Lonnie and I agree that, in fact, Dr. Hansen is more conservative. I think Lonnie has a more dire view of what's going on right now then Jim Hansen does.

FLATOW: We're talking about global warming and melting glaciers this hour, in TALK OF THE NATION SCIENCE FRIDAY, from NPR News.

Lonnie, do you think Jim is being conservative? Jim Hansen is not yelling loud enough?

Dr. THOMPSON: I think he's conservative. You know, in his December talk, I mean he talked about the tipping point in the climate system, and his best estimate is that we maybe have ten years before we cross this tipping point. And I'm not sure that we're not closer.

Mr. BOWEN: Yeah, Lonnie, would you mind talking a little bit about this evidence from the plants on Kalkiya(ph) that you found, you uncovered in 2004? That's kind of relevant to this, I think.

Dr. THOMPSON: One of the things that is very telling is, as these glaciers retreat, they're releasing things that they have captured in the past. And along the margins of the Kalkiya Ice Cap there are plants, wetland plants, there's no woody tissue. But these plants are perfectly preserved and they're coming out from the retreating margin of that ice cap.

And these plants date, we've collected in 25 different sites around this glacier, and these plants date between five and six thousand years in age, Carbon-14 dating. And the only way that you could preserve these very fragile plants is to have them covered with ice for that length of time. And that tells us that for that ice cap, it has not been smaller than today for over 6,000 years.

And so that kind of gives us, starts to give us a perspective on the current climate change that we're seeing.

Mr. BOWEN: Yeah, we've seen evidence, even in North America in Alaska, of artifacts are now coming out of the permafrost.

FLATOW: Exactly.

Mr. BOWEN: What about the other plants, Lonnie? Has your thinking changed on those? The ones you discovered in 2004?

Dr. THOMPSON: No, they haven't. We found one site where we have a collection of these plants that are Carbon-14 dead. Dated in two different labs, they are over, to be Carbon-14 dead they have to be over 50,000 years in age. But what we're looking for is to see this in other valleys along this ice cap to confirm that there's not something unusual about that collection site.

FLATOW: And just briefly, Lonnie, where are you headed next?

Dr. THOMPSON: We're headed to Nanu Nami(ph), in the far southwestern Himalayas. This is a project with our Chinese colleagues. It's about a five day journey west of Lassa. It's right about the town of Barong. Barong is, the city is over 1,500 years old. It was on the old North-South Silk Road across Tibet. Eighty- five percent of its water comes from the glaciers of Nanu Nami, all of which are retreating. And so, there is a direct human impact with the loss of these water supplies from these mountain regions.

FLATOW: Well, good luck to you on your travels, and thank you for taking time to join us today.

Dr. THOMPSON: Thank you, Ira.

FLATOW: Lonnie Thompson is Distinguished University Professor and Senior Research Scientist in the Byrd Polar Research Center at Ohio State University, in Columbus.

Also, Mark, thank you for taking time to be with us today.

Mr. BOWEN: Thank you, Ira.

FLATOW: Mark Bowen is author of Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains. It's out by Henry Holt. A really interesting book, great photos, if you want to see what we're talking about, about melting glaciers.

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