Editor's Note: Today we continue our Friday content partnership with Green Options, with Maria Surma Manka sharing some disconcerting news on rapid changes in the U.S. Great Lakes region. This post was originally published on September 26, 2007.
Photo courtesy of the US EPA
Great Lakes National Program office |
For starters, the lake’s rapidly warming water temperature has baffled scientists. Although they knew it has been slowly heating up, "it went bananas" beginning 30 years ago: about 75 percent of the 6-degree increase in water temperature has happened since 1980.
Scientists at the Large Lakes Observatory in Duluth, MN thought they had made a mistake: How could the lake be warming up twice as fast as the climate around it?
Much like the effect scientists are seeing in the Arctic, the lack of ice coverage has caused the lake to warm up faster than expected. The ice normally reflects sunlight back into space and keeps the water cooler underneath. But as warmer temperatures creep in and the average annual ice cover shrinks, the darker open water absorbs the heat and cranks up the lake temperature even faster. The vicious cycle continues, as warmer water temperatures mean less ice, which means more open water…
The spring turnover is also happening much earlier than normal. The turnover happens when the icy surface water warms up and mixes with the rest of the lake, creating a layer of warm water on top. This has been happening 10-14 days earlier than it was 25 years ago.
Last summer, Lake Superior’s temperature broke a record when it was measured at 75 degrees. Typically, it barely got above 60.
So what does this mean for the rest of us? In the states surrounding Lake Superior and the other Great Lakes, rapidly increasing temperatures mean more invasive plant and animal species from the warmer climes. Lake Michigan has already seen sea lampreys almost wipe out its lake trout. Changes to wildlife would also hurt tourism, causing a major economic blow.
It also means big disruptions to the region’s commerce. Lake Superior is at its lowest water level in 81 years, and while scientists say global warming may not be the sole cause of that decline, it is a factor. Cargo ships — some that carry wind turbine parts over from Europe, ironically — must haul lighter loads so they don’t get stranded in port. That means less efficient shipping and transportation of goods around the world.
While landscapes and habitat have changed over the centuries, the swiftness of this latest change has unsettled scientists. Meanwhile, the rest of us need to prepare to adapt to the inevitable changes have begun and take meaningful action to ensure that it doesn’t get worse.
