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Ice levels on Great Lakes reach highest point in decades

By Ian Dillingham, Daily News Editor
Published February 19, 2014

As students return home for spring break, those who live in coastal regions surrounding the Great Lakes could witness some of the highest ice levels in decades.

As of Wednesday, ice coverage across the Great Lakes was hovering just above 85 percent, meaning only a small fraction of the surface areas of the lakes remain unfrozen, according to George A. Leshkevich, a researcher at the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory.

The Ann Arbor-based NOAA lab, one of seven similar national labs, conducts the majority of the administration’s Great Lakes research. The lab partners with the University’s Cooperative Institute for Limnology and Ecosystems Research, which is overseen by the School of Natural Resources and Environment. CILER was founded with the goal of “fostering University and NOAA partnerships in the Great Lakes region,” according to the CILER webpage.

NOAA uses satellite imagery, shipping reports and aircraft observations, in conjunction with computer models, to estimate the ice coverage throughout the winter months. Leshkevich said the southern lakes typically see ice levels peak around the middle to end of February, where the northern lakes see their peak around the beginning of March.

The high ice levels are likely due to the early onset of winter weather this season, combined with last month’s polar vortex, which caused below-average temperatures across many of the lakes. The ice levels contrast low to moderate levels in the last couple years.

“The warming effect that we’ve seen — both air temperature and water temperature — and then with polar vortex come down draws the heat out of the lake, change things radically, so we end up this year with a lot of ice cover,” Leshkevich said.

While the ice is particularly severe this season, Leshkevich said this demonstrates the increased variability of recent years. Historically, ice levels fluctuate from year to year, but when averaged out, ice levels over the last several decades have been on a very gradual decline.

“The ice cover has been variable throughout the years, even in the 70s and 80s,” he said. “Overall it will still be downward, but it seems like we're seeing greater fluctuation in recent years.”

Average ice cover at this point in the season is 35 percent, according to Leshkevich. The current levels are the highest since 1979, when the lakes were almost 95 percent covered.

While the ice may present obstacles for ships and beachgoers, Leshkevich and other scientists said it represents an important component of the Great Lakes’ ecosystems. Surface ice prevents winter evaporation, which helps maintain water levels, and some species of fish rely on the ice to protect nesting grounds from winter storms.

Several factors — mainly wind, rain and air temperature — could influence whether the ice continues to grow or begins melting. If cold weather persists, the ice could theoretically continue to grow and approach nearly 100 percent.

While the early winter season may have been the key player in the ice formation this year, Leshkevich said global climate change may be playing a role in the overarching change in fluctuations.

“A lot of climatologists attribute (the ice) to both natural variability and perhaps some to climate change, to global change,” he said. “At least that’s what I'm hearing from them.”