Weathering Change: Glaciers Melt, Water Rises

25 February 2013
Published in Environment
Written by  Kim Schuske
Weathering Change: Glaciers Melt, Water Rises Edubucher, Creative Commons

Changing weather patterns, melting glaciers, longer more severe droughts, and rising storm surges are in our future according to scientists. Today we start a series, Weathering Change, looking at how some people are thinking about this new reality.


Lonnie Thompson is a scientist who drills ice cores from some of the highest mountain top glaciers in the world. He was profiled as one of the world’s top explorers in National Geographic’s January 125th Anniversary issue. I talked to him about how higher temperatures are affecting tropical glaciers, found in high mountains near the equator. He describes the dramatic changes he has seen over his 38 year-career.

KIM SCHUSKE: What have you seen in your work that tells you how fast this is moving?

LONNIE THOMPSON: I think probably the advantage that I have is the fact that I have been able to conduct 57 expeditions in 16 different countries.

And I think when you see change taking place, it really makes it real. I think if more people lived where they could actually see a glacier, and then make those observations, then there would be a lot less debate about if it’s happening or not.

KIM SCHUSKE: What have you seen?

LONNIE THOMPSON: Well if we look at Peru, the Quelccaya Ice Cap where there was the first tropical glacier that I visited back in 1974. That ice cap has lost 25% of its area since I was a graduate student. I mean, it’s the largest tropical ice cap on earth.

In more recent years, things are coming out from the retreating margin. Plants are in growth positions that haven’t seen the light of day for over 5,000 years. They tell us that this glacier hasn’t been smaller for at least 5,000 years. That kind of puts it into a perspective.

KIM SCHUSKE: It’s just happening all across the globe? That the ice is melting?

LONNIE THOMPSON: You look up in the Brooks Range in Alaska, 100% of glaciers in that range are retreating in today’s world. In Southeast Alaska, 98% of the glaciers are retreating in that zone.

If you’re in the Himalayas, there are over 46,000 glaciers there. Not too many of them have been studied, but our Chinese colleagues are monitoring 680 of those glaciers. 95% of those glaciers are retreating in today’s world. If you go to the Alps, where we have our longest documented histories, 99% of the glaciers are retreating. If you go in the tropics, where we’ve been spending a lot of time working on the glaciers, 100% of the glaciers are retreating in that zone.

So, it’s the scale of this ice loss that we’re really concerned about.

KIM SCHUSKE: What are the consequences of this loss?

LONNIE THOMPSON: Well the consequences are that glaciers are just water on land, frozen water. And when they melt the water makes its way through the rivers into the worlds oceans and they contribute to sea level rise.

If we were to remove all the ice that’s now on land, sea level would rise 70 meters [230 feet] just from the melting of the ice. Then there would be a thermal expansion of that water, simply because it’s warmer, so that you’re looking at a world where the geography would be totally different than the world we live in.

KIM SCHUSKE: But it’s not likely that all of the ice is going to melt anytime soon?

LONNIE THOMPSON: Yeah, well that’s our hope, yes.

KIM SCHUSKE: How much ice would cause major damage if it melted?

LONNIE THOMPSON: Our projections are that temperatures of our planet on average will be 3 degrees Celsius [5.4 degrees Fahrenheit] warmer at the surface by 2100, at the current track that we’re on.

And if you look at the history of our planet you look at the last time we were 3 degrees warmer, 2 to 3 degrees warmer, you have to go back to the Pleistocene, about three million years ago.

And then if you ask what was sea level three million years ago? We’re looking at numbers between 25 meters and 35 meters [82-155 feet] higher than today.

KIM SCHUSKE: Can you just give an example? If 8% of the ice melted, what would that do to the coasts of the U.S.?

LONNIE THOMPSON: Well if you’re looking at losing 8%, you’re looking at a sea level rise somewhere between 5-6 meters [16-19 feet], so you would lose half the state of Florida. You would lose a large part of Louisiana, you would lose a number of cities at sea level, large parts of them like New York City, Miami would be totally gone.

And of course what makes it so different today than in the past - Because glaciers have grown and retreated through the history of our planet. There have been times when we had no ice on land and sea level was much higher. - But we’ve never had 7 billion people that have built all this infrastructure at sea level.

It’s that risk that makes our time, and the changes that are occurring in today’s world, so important.

Lonnie Thompson is Distinguished Professor in the School of Earth Sciences and a Research Scientist in the Byrd Polar Research Center at Ohio State University. Last year he underwent a heart transplant, but still plans to go to Tibet next where, according to National Geographic, he hopes to find the oldest ice on earth. The interview took place in 2011.

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