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PRI's Environmental News Magazine

Great Lakes Ice

Air Date: Week of November 24, 2000

Scientists who take measurements of the thickness of ice on the Great Lakes say there’s been less and less ice cover in recent year, and global warming may be the reason. The Great Lakes Radio Consortium’s Lester Graham reports.

Transcript

TOOMEY: Let's turn now to North America. Folks in the Great Lakes region are noticing less ice over those waters and wonder about a link to global warming. Lester Graham of the Great Lakes Radio Consortium prepared this report.

GRAHAM: Researchers who study the Great Lakes environment are putting together a puzzle. They're piecing together the history of ice on the Great Lakes. When they're finished, they'll have specific data for the last 30 years and a rough sketch of ice patterns for the past 150 years. But there's something important they've already noticed: the last few years have seen a lot less ice on the lakes. Raymond Assel is with the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Lab.

ASSEL: If we continue to have these relatively mild ice seasons, say for the next five years or so, then that would certainly indicate that we are under a new ice cover regime in the Great Lakes region. But, it's much the problem that we have with trying to detect global warming. You know, once you can tell positively that you have it, you've already been in it for a while.

GRAHAM: Assel is not saying global warming is causing less ice on the Great Lakes. But he says it fits the scenario some scientists are predicting and those predictions are leading to some planning for the future. One economist at the University of Illinois at Chicago has already studied how global warming might effect one of the Great Lakes' most important industries.

(Harbor Sounds)

GRAHAM: Scrap, steel, stone and grain are among the hundreds of products shipped in and out of the Great Lakes and global warming would likely mean a longer shipping season because there would be less ice to block the channels and harbors. That's the good news. Here's the downside. Since ice covers open water it prevents evaporation. With less ice, there's more evaporation. Warmer weather would also mean reduced snowmelt and,ultimately, lower water levels in the lakes. That's a scenario University of Illinois at Chicago economist Richard Kosobud and his colleagues have been seeing for the last few years.

KOSOBUD: And these big ships, which are bringing out the things we produce here and bringing in raw materials, are just squeezing a number of these locks. And if the Great Lakes levels decline, then these locks will have to be rebuilt or the ships will have to be redesigned, and some port facilities will have to be redesigned and that could be expensive.

GRAHAM: Kosobud calculates the economic impacts could be great. Something, he says, planners and builders should keep in mind.

KOSOBUD: In a sense, we don't want to spend a lot of money now preventing something where we're kind of uncertain as to the exact decrease in lake levels, but they certainly ought to be built in on the margin. Planners, I think, ought to keep in mind that there are going to be - if global warming is serious - there are going to be significant changes in water temperatures, in lake elevation and ice cover, and these ought to be built into the plans.

GRAHAM: At the Waukegan Marina, just north of Chicago, water marks in the gray piers show just how far Lake Michigan's level has dropped. Mary Walker is manager of the harbor.

WALKER: Well, it's been a headache already and probably the biggest problem that we're suffering in Waukegan is that we have fixed piers. "Fixed piers" means that they don't float up and down as the water rises and falls. So, when you have highs and lows then sometimes fixed piers are a problem.

GRAHAM: Walker says she's also hired someone to dredge the channels to make sure the boats can get in and out of the harbor. But some sailboat owners have already moved their boats to deeper harbors.

WALKER: My biggest worry is that water levels will drop to the point that the harbor isn't usable. I'm sure that we're not going to see that I mean that would be quite a few more feet and I certainly hope that is and I'm hoping this is just cylicle but it certainly is a cause of concern.

GRAHAM: Scientists don't know yet how much the climate will change but almost all of them now agree warming of the planet is underway. Dan Lashof, Senior Scientist with the environmental group National Resources Defense Council says it's a pretty safe bet that the reduction in ice and lower water levels are part of the trend.

LASHOF: I think it makes sense to anticipate that climate will continue to change over the next several decades and to begin to plan for that and to build an expectation of changing climate into long-lived infrastructure investments. Of course, at the same time we should be doing everything we can do to reduce the pollution that causes global warming.

GRAHAM: In the meantime, the scientists at the Great Lakes Environmental Research Lab are compiling Great Lakes ice maps from several sources and comparing them from year to year. They hope to soon be able to tell whether the current ice pattern is just temporary climate variability or part of an ongoing warm-up of the planet's surface. For Living on Earth, I'm Lester Graham.

 

 

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