 Radio Script 2002 __________________ Alaska's Melting Glaciers INTRO: Evidence of a warmer climate seems to be everywhere these days. Warmer temperatures, changing vegetation, and melting permafrost are some of the signs of a changing climate. Now scientists say Alaska's glaciers are melting at an alarming rate. Doug Schneider has more, in this week's Arctic Science Journeys Radio. STORY: Glaciologists from the University of Alaska Fairbanks Geophysical Institute measured the thickness of more than 70 glaciers across Alaska, from alpine glaciers in the high Arctic to the vast ice sheets of Southeast Alaska. In findings published recently in the journal Science, lead researcher Keith Echelmeyer says the state's glaciers have gotten significantly thinner. ECHELMEYER: "We're finding that they're all thinning quite a bit, and how and why or how it's related to geography or different climate zones we haven't figured out yet." Using maps made in the 1950s by the United States Geological Survey as a starting point, Echelmeyer and colleagues in 1990 surveyed dozens of glaciers. Echelmeyer, a pilot, measured the elevation of dozens of glaciers using a small plane equipped with a laser altimetry system. By comparing the elevations on the 1950s maps to the altimetry measurements, Echelmeyer determined that more than 85 percent of the glaciers had lost vast portions of their volume between 1950 and 1990. But while the laser system is accurate to within a foot, Echelmeyer says the USGS maps probably weren't as accurate. ECHELMEYER: "The topographic maps themselves are not so accurate. And so much of the error in our calculations comes from the maps. They're good maps, but they're not good to within a foot." To get more precise measurements, Echelmeyer and his colleagues continued their altimeter surveys of the glaciers over the next decade. During this period, many of the state's most recognizable glaciers thinned at twice the rate seen in the 1950s. ECHELMEYER: "The rate of change is bigger now than it was before. Mendenhall Glacier is a normal glacier and its thinning quite a bit. Many of the glaciers by Seward we've looked at. And of those, almost all are thinning quite rapidly. You see Exit Glacier, where people walk up right from Seward. That one has thinned quite a bit and is getting shorter. I think we've studied many of the glaciers people see a lot and most seem to be thinning, too." Overall, the glaciers researchers studied lost more than 2,000 cubic kilometers of ice volume since the 1950s, according to co-researcher Anthony Arendt. That's enough ice to fit inside a box about 10 miles high. ARENDT: "The rate for the period of the mid-1950s to mid-1990s is about 52 cubic kilometers per year. So if you multiply that by about 40, you get about 2,000 cubic kilometers over a 40-year period. So that's a lot of ice to lose." Where all that meltwater from these glaciers goes is another concern for scientists. Arendt says Alaska's glaciers are responsible for at least nine percent of the global sea-level rise during the past century. ARENDT: "One of the big issues in this study is trying to figure out what is the contribution of all the glaciers in Alaska to global sea level rise? It turns out that the estimates in the past from other studies were quite a bit lower than what we're estimating in this study. Past studies only had data from about three or four glaciers in Alaska. Our estimates show about a .14-millimeter-per-year rise in sea levels due to the melting of glaciers in Alaska during a 40-year period from the 1950s. And in the last decade or so we're seeing about .27 millimeters per year, so that rate has gone up quite a bit." Keith Echelmeyer is reluctant to attribute Alaska's melting glaciers to man-made global warming. But he says that with all the other circumstantial evidence of climate change, it's a theory that's hard to dismiss. ECHELMEYER: "I think if you look at all the changes like carbon dioxide in the atmosphere, these have all occurred very rapidly in the last 50 to 100 years. So I think they are all related, but we can't prove it with our work. We haven't shown that this is directly related to something man is doing." Researchers next plan to look for patterns in how these glaciers are melting. They'll try to discover whether rates of thinning vary from one geographic location to another, and they'll try to determine the role of climate warming on the thinning glaciers. OUTRO: This is Arctic Science Journeys Radio, a production of the University of Alaska Fairbanks School of Fisheries and Ocean Sciences’ Sea Grant Program. I'm Doug Schneider. Audio version and related Web sites (sidebar at top right) Thanks to the following individuals for help preparing this script: Keith Echelmeyer, glaciologist Anthony Arendt Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks. The shortcut to our ASJ news home page is www.asjnews.org.
2002
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