08/21/2006

Record-Eagle/Sheri McWhirter
Roger Bergstedt, supervisor at the U.S. Geological Survey Hammond Bay Biological Station on Lake Huron, said the duct tape on the breakwall marks the high water level in 1986.

Climate change having impact?

Lake water levels shifting, basin may be tilting

By
Record-Eagle staff writer

ROGERS CITY — Dawn came as a change in shades of gray, as a steady rain spattered the otherwise calm surface of Lake Huron.

A commercial shipping vessel crept across the horizon and water warmer than the air lapped against a rocky shoreline. A gray morning turned partly cloudy a couple of hours later.

About 13 miles westward along the coast, a retired hydrologist from the National Oceanic and Atmospheric Administration prepared to discuss with a group of journalists climate change and shifting water levels in the Great Lakes.

"I'm with the majority of scientists who believe climate change is a manmade cause and effect," Frank Quinn said.

That's an opinion he can utter now that he's retired, he said. President George W. Bush controls what federal agencies can say about climate change, Quinn said.

"He has muzzled people at NOAA and at NASA. We have a real problem with the administration," Quinn said.

Quinn, a water sciences expert, explained the way lake ecosystems work, from factors affecting water levels, the way top and bottom level lake water does a "turnover," and also how the entire Great Lakes Basin may be tilting.

It is a complex system involving changes in water runoff, diversion, evaporation and both winter ice levels and storm activity. Then there are annual or multi-year changes in basic hydrological components, Quinn said.

"We're still rebounding from the glaciers ... Duluth is sinking" at a rate of 12 inches per century (*), Quinn said. "Land is rising is some places and sinking in others."

Quinn said climate change may affect water temperatures, evaporation rates and subsequent water levels. There are indications that climate change may alter lake "turnovers," he said.

"On Lake Michigan, anyway, we may not get that turnover," he said.

It is a process by which highly oxygenated water is moved to the bottom of the lake once it reaches 39 degrees, or 4 degrees Celsius. The cooled water molecules reach maximum density and sink, while warmer lower level waters rise.

"Without that, the lower levels of the lake could become totally deoxygenated and devoid of life," Quinn said.

Roger Bergstedt, supervisor at the U.S. Geological Survey Hammond Bay Biological Station on Lake Huron, said water levels certainly have changed over the years at the facility. A large area of boulder rip-rap was installed in the winter of 1985 and 1986 when high water levels threatened the station, he said.

Quinn said that was also the year of record high water levels in southern Lake Michigan, when homes were falling into the inland sea. The highest lake level recorded for both Lakes Huron and Michigan was in 1838, he said.