Four of the five Great Lakes have shrunk big time, alarming some scientists. People who live near lakes Michigan, Huron, Erie, Superior and Ontario are worried, too.
The lakes touch Michigan, Illinois, Indiana, Ohio, Pennsylvania, Wisconsin, Minnesota, New York and two Canadian provinces, Ontario and Quebec. So why should people in other places care?
"The Great Lakes is the major freshwater resource in the United States," said Frank Quinn, a lake scientist with the National Oceanic and Atmospheric Administration.
From August 1998 to August '99, lakes Huron and Michigan dropped 17 inches, Quinn said. Lake Erie plunged 19 inches. Lake Ontario dropped 7 inches. Superior, the biggest lake, dropped 10 inches between March 1998 and March '99, but rose again after heavy rains last summer.
Quinn called the drops "phenomenal." He said they were abnormal and caused by global climate changes.
Todd Thompson, a geologist at Indiana University, thinks the drops may be normal -- part of the lakes' 5,000-year geologic history of ups and downs. But they might be abnormal, he said.
The most recent lake drops started with El Nino, the warm-water weather system of 1997-98. It warmed up Lake Superior, causing less snow, which quickly melted and evaporated instead of running off into the lake. The last six months of '98 were pretty dry . No rain, no new lake water. Water levels dropped, widening beaches and exposing long-buried rocks.
What's next? Most computer models predict another large drop in lake levels because of global warming by 2030 -- as much as 3 feet in Michigan and Huron and 2 feet in Erie.
"But one model shows levels would stay about the same as now -- with global warming," Quinn said.