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PRI's Environmental News Magazine

Melting Snow Caps

Air Date: Week of

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CURWOOD: This is Living on Earth. I'm Steve Curwood. The snows of Kilimanjaro are receding so fast that famous visitor Ernest Hemingway might not recognize the icy African peak he wrote about just a few decades ago. As the effects of global climate change begin to be recognized all over the planet, tropical mountain glaciers are melting at unprecedented rates. Lonnie Thompson is a geology professor at Ohio State University. He's been mapping and monitoring the Mount Kilimanjaro ice field, as well as ice caps in Peru and Tibet. He joins us now. Welcome, Professor Thompson.

THOMPSON: Thank you.

CURWOOD: Now, you've been taking measurements at Kilimanjaro for the past two decades. What specifically are you seeing?

THOMPSON: One of the things we did was to map it, to have aerial photographs flown. And an interesting part of Kilimanjaro is, it has this long history. And there are actually five maps, now, for the mountain. So we were able to compare the map we made from 2000 with that series of maps. And if you look at the first map, made in 1912, there was 12.1 square kilometers of ice on the mountain. And in our most recent map there's only 2.2 square kilometers of ice remaining. That's a loss of 82 percent of the area of ice on the mountain since that first map was made.

CURWOOD: How fast has it disappeared in recent times?

THOMPSON: In 1989 there was 3.3 square kilometers of ice. So we've lost essentially 33 percent of the ice since that last map was made in 1989.

CURWOOD: Now, you're also studying a particular glacier in the Peruvian Andes. How do you pronounce the name of that place?

THOMPSON: It's Quelccaya. It's a Quechuan Indian name.

CURWOOD: What's the situation there?

THOMPSON: In the first measurement period, which was 1963 to '78, this ice cap was retreating at 4.9 meters per year. Now, it has accelerated in its rate of retreat as we've come forward in time. And in the most recent period, 1998 to August of 2000, it has increased to 155 meters per year. That's an increase of about 32 times over the initial measurement period.

CURWOOD: What are the indications to you that what you're seeing aren't just part of the natural state of glaciers that would ordinarily wax and wane over time?

THOMPSON: This is a very important point; that's exactly correct. Glaciers do advance and recede. For a glacier like Quelccaya you find out that the retreat since the last cold period, the Little Ice Age, that that retreat has only been of the order of one to three meters per year. The most recent period, 155 meters per year is much larger than any of the previous rates of retreat that we can get a handle on.

CURWOOD: At the rate that the ice is melting on Mount Kilimanjaro, when will it be completely without any snow or ice?

THOMPSON: For Kilimanjaro, the ice will disappear by 2015. If you do the same calculations on this Quelccaya ice cap in Peru, its estimated demise, if the current rates of retreat continue, will occur some time between 2010 and 2020. So about the same period of time.

CURWOOD: Do these glaciers shrink because the air is warmer or there's less snow, or why, do you think?

THOMPSON: If we look at the twentieth century, snowfall has actually been average to above average. And yet the glacier is retreating. So the driver here has to be temperature.

CURWOOD: What are the environmental effects of these glacier melts?

THOMPSON: Well, the impacts are already being felt in these countries. For example, Kilimanjaro, when we were there in January, we were in the governor's office, and two sisters came in from a local hospital. The hospital had been working for 100 years and they had run out of water. The water comes from streams coming off of Kilimanjaro, and the stream had dried up. Glaciers are kind of like a natural dam. They store water, especially in the wet season, and then in the dry season they melt and allow water discharge into streams. So locally, they're already seeing the impact. If you go to South America, Peru has the most tropical glaciers in the world. What we observe happening on Quelccaya is actually happening to all the glaciers in the Andes in Peru. And as a consequence of this, there has been a drop in hydroelectric power production, and consequently there has been a loss of power in some of the municipalities like Lima, Peru. And to make up for this, of course, they are building fuel-burning power plants. And of course, this is likely to contribute to the problem.

CURWOOD: You know, you could almost say that history is melting away here.

THOMPSON: We believe 20 years from now, if you want to see an ice core sample from Kilimanjaro, you'll have to come to the freezers at Ohio State University, where we have an archive stored at minus 40 degrees C. But it is unfortunate that you would have to come to a freezer to see these beautiful ice fields.

CURWOOD: Lonnie Thompson is a professor in the department of geological science at Ohio State University. Professor, thanks for joining us today.

THOMPSON: Been my pleasure.

(Music up and under: Patrick O'Hearn, "Unusual Climate")



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