- Mark McDowell
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Great Lakes Are on Thin Ice
The Great Lakes winter ice cover has dropped dramatically over the past 40 years, according to a new report. On average, peak ice has fallen by 71 percent; Lake Michigan’s ice cover has shrunk even more than that.
Researchers at the National Oceanic and Atmospheric Administration (NOAA) compared satellite photos dating to 1973. Jia Wang, a NOAA ice climatologist, said the changes are stark. In a year like 1979, ice covered about 94 percent of the lakes in the coldest months of that winter. “This winter the maximum ice cover is about five percent,” Wang said. “It’s the lowest ever since the satellite era.” The drop in ice cover is largely a result of rising temperatures due to climate change. There are also other factors at play this year in particular, such as El Nino weather patterns. According to Wang, such a loss of winter ice can cause several problems for the Great Lakes ecosystem. For example, it can accelerate wintertime evaporation from the lakes, which could reduce water levels. The trend could also stimulate more and earlier algae blooms, which damage water quality and habitat. Additionally, it leaves the shoreline more exposed to waves, exacerbating erosion.
The changes in the Great Lakes could make them a dead zone. According to the University of Michigan’s Don Scavia, “By end of the century, Illinois will feel like Texas. And Michigan will feel like Arkansas.” Scavia, who leads the university’s Environmental Sustainability Institute, laid out a disconcerting list of changes already taking place in the Great Lakes region as the result of climate change. According to Scavia the changes include the last frost in spring occurs earlier and earlier, while the first frost in fall is later and later. This is extending the growing season, as well as changing what plants and crops can grow in the region. Storms are more intense, and major weather events happen more frequently.
The most alarming potential scenario is the possibility that the Great Lakes to become a dead zone, a body of water that lacks oxygen and no fish or plants can survive. This happened to Lake Erie in the 1960s, resulting from algal blooms caused by industrial pollution, human waste and farm run-off. Lake Erie’s devastation led to the passage of the federal Clean Water Act in 1972. Oxygen levels in the lake improved in the 1980s, but worsened again in the 1990s. Recent studies have shown that algae in Lake Erie is returning.
Although lakefront residents may enjoy the more temperate beachfront this year, ice is crucial in maintaining coastal wetlands and water depth. The wetlands act as an incubator for wildlife in the Great Lakes basin. Wetlands — the marshy shorelines that harbor numerous plants and animals — require the constant variation of the seasons and Great Lakes water levels. The lack of substantial ice coverage results in greater evaporation, which leaves water levels across the Great Lakes lower over the long term.
“Having low water levels next year doesn’t make me nervous. Having low levels over the last 10 years makes me worry,” said Donald Uzarski, director of Central Michigan University’s Institute for Great Lakes Research. “We’ll see what happens with respect to the water levels. When the water level’s lower, the coastal wetlands stretch out towards the water’s edge,” out into exposed shoreline areas that are usually under water.
Rather surprisingly, extreme summer and winter temperatures are actually considered good for wetlands. These conditions can feed the growth of wetlands, which are “very dynamic and very responsive to water levels,” according to Kurt Kowalski of the United States Geological Survey. Climatologists studying lake ice have noticed a steadier pattern of temperatures within the last 10 years. “The frequency of mild winters has been on the increase. We’re certainly in a trend for milder winters now,” said Ray Assel, a retired climatologist, recently of the Great Lakes Environmental Research Laboratory.
According to the Canadian Ice Service, ice cover on the Great Lakes for the week of March 5, 2011 was approximately 36 percent and close to the historical average of 38 percent. By contrast, ice cover for the week of March 5, 2012 has been exceptionally low and is only about 12 percent.
Writing on the earthsky.org website, Deanna Conners says that “In fact, ice cover has been so low this year on Lake Erie that officials began removing the ice boom that prevents large chunks of ice from flowing out into the Niagara River on February 28, 2012. This is the earliest date for removal since the boom was first installed in the mid 1960s. The ice boom acts to prevent ice damage to hydropower intake equipment. Early boom removal is our harbinger of an early spring in western New York. Dare I say that I think the groundhog was wrong this year?”
Another sign of the times comes from the Daily Great Lakes Seaway Shipping News, which notes that “Shipments of iron ore on the Great Lakes totaled 3,587,016 net tons in January, an increase of 24 percent over a year ago, and 57 percent ahead of the month’s five-year average”. In typical winters when the Great Lakes have a more widespread ice cover, the billion dollar shipping activity comes to a virtual halt. Click on this link to view a map of the extent of Great Lakes ice during the cold and snowy winter of 1979, the last time the Great Lakes were more than 95 percent frozen over.