When you see your lake ice over two weeks earlier than in recent years (as we did here on Birch Lake), and when you recall a winter where ice anglers had to get extensions on their augers to drill through to water, it’s hard to imagine climate change having much effect on local ice conditions.
And yet climate scientists now say lake ice may be one of the most significant casualties of a warming planet. According to a report published early 2019, it’s not just glaciers and polar ice caps that are at risk.
Imagine ice fishing, ice skating, snowmobiling and other pursuits starting later and ending earlier each winter. Or consider more freeze-thaw cycles making the ice less stable so driving a car or truck onto it is simply too hazardous.
The latest lake ice study, completed with involvement from scientists at the University of Wisconsin-Madison Center for Limnology, forecasts that a decline in lake ice will have well impacts beyond such inconveniences. It says lakes here in the northern reaches are highly sensitive to warmer temperatures, and lake ice is among the resources most at risk from a changing climate.
The researchers estimated how many lakes in the Northern Hemisphere are in danger of shorter iced-in seasons or loss of ice altogether. They report that changes in lake ice are related to factors like air temperature, depth of the water, elevation, and shoreline characteristics. They say some 15,000 lakes that once froze over every winter no longer do so consistently.
So far that refers to lakes farther south than we are; it doesn’t include lakes in Vilas and Oneida counties or in Wisconsin’s and Minnesota’s northern reaches. But as climate continues to change, the duration and extent of ice cover will be affected over a larger area.
The impact on lake ice depends on which scenarios are used in making the predictions, according to John Magnuson, a professor emeritus and director emeritus at the Center for Limnology, one of an international group of scientists who published the study in Nature Climate Change, an academic journal.
For example, if the average worldwide air temperature goes up by 2 degrees C, (3.6 degrees F), more than 35,000 lakes would see only intermittent ice by the end of this century. That would affect nearly 400 million people who live an hour or less from the water.
In the worst case, where temperatures rise by 8 degrees C (14 degrees F) more than 230,000 lakes and 650 million people in 50 countries would be affected. The zone in which lakes freeze over would move beyond this country’s northern border and into northern Canada.
This would have consequences beyond loss of winter recreation. For example, lakes not frozen would see greater evaporative water loss in winter; they would also warm up faster in spring, reducing levels of oxygen in the water. More harmful algae blooms and harm to fish and wildlife would likely ensue.
It’s a sobering scenario, one to be concerned about as we debate policies aimed at combatting climate change.
Ted Rulseh resides on Birch Lake in Harshaw and is an advocate for lake protection and improvement. His Lakeland Times and Northwoods River News columns are the basis for a book, “A Lakeside Companion,” published by The University of Wisconsin Press. Ted may be reached at [email protected].