Great Lakes Ice: Missing in Action
from Wildlife PromiseAfter the fourth warmest winter on record, the extent of ice covering the Great Lakes is at a near record low. The extremely low levels are consistent with a study showing significant declines in ice levels from 1973-2010. This trend is yet another indicator of global warming causing odd-ball winter weather in our backyards.
Skiing on Lake Michigan
When I was 10, we rented a house along the shores of Lake Michigan for a winter weekend. Growing up in Chicago, I had spent many hours playing on the beach in the summertime. But, this was my first visit to the lake during winter. And it was magical, like something out of an actual winter wonderland. We spent hours cross-country skiing through forests frosted with icicles.
Most amazing of all was the lake. In contrast to the summer waves lapping the shore, there was ice extending probably hundreds of yards out into the lake. The ice was more than thick enough for us to ski right out on the lake! I still remember how thrilling this felt!
After a winter like 2011-2012, these sorts of memories feel distant, almost archaic. With this year’s warm winter weather, the lakes have had very little ice. Satellite images indicate that only 5 percent of the lakes froze over, much less than the around 50 percent ice cover that was typical when I was a child.
Great Lakes Are Losing Ice
It’s not just this year. The annual mean lake ice area observed on Lake Michigan has declined by 77 percent from 1973 to 2010, according to a recent paper published by Jia Wang and other researchers at NOAA’s Great Lakes Environmental Research Laboratory and the University of Michigan. In fact, all of the lakes have seen a long term decline in ice cover, with an average loss of 71 percent.
The authors point to increasing winter air temperatures as an explanation. Over the same time period, winter temperatures increased by 2.7 – 4.0 degrees Fahrenheit on average in the Great Lakes region. Water temperatures are increasing even more. With less ice cover to reflect the Sun’s rays back to space, the lakes can absorb more heat each year.
Of course, the decline in ice cover isn’t a steady downward march. The year-to-year variability caused by natural cycles is still an important factor in how much ice will form in any particular year. This new paper also sheds light on the roles of the El Nino-Southern Oscillation and the Arctic Oscillation in controlling the short-term variability.
More than Ice at Stake
The loss of winter-time ice in the Great Lakes has ripple effects for wildlife and outdoor activities alike. NWF staffer Melinda Koslow summarizes some potential impacts of lost ice: dangerous algal blooms, the loss of protection for fish eggs and near-shore wetland habitats, and increased evaporation leading to lower lake water levels. Meanwhile ice fishing activities have been curtailed across the Midwest and in other northern states this year.
The last few months serve as a window into what winter will usually look like in a warmer world. Let’s also use this winter as a wake-up call to start taking actions to preserve the outdoor winter traditions that we each treasure.
Email officials at the U.S. Environmental Protection Agency to let them know you support limits on carbon pollution from coal-fired power plants.