If humans continue to release greenhouse gases into the atmosphere at current rates, we should be prepared to say goodbye to ice-covered winters on the Great Lakes.
That’s the conclusion of a new study from researchers at Toronto’s York University, who used historical data from lakes throughout the Northern Hemisphere to track the steady loss of Earth’s ice and predict how ice loss will progress if we act now to curb the effects of climate change — and if we don’t.
Bridge Michigan interviewed Sapna Sharma, an associate professor in York’s biology department and the study’s lead author, about what Michigan and the rest of the Northern Hemisphere can expect as climate change warms our winters.
The conversation has been edited for clarity and brevity.
Which lakes are most at-risk of losing their ice?
In the Great Lakes region, the deepest lakes are the most sensitive to ice loss. Shallow lakes will generally still freeze, with some exceptions in a really warm winter. But these large, deep lakes like Lake Superior, Lake Michigan and Lake Champlain are already experiencing ice-free years. That will get worse in the coming decades.
How did you arrive at that conclusion?
We used historical ice data to develop statistical models for the future for 1.35 million lakes.
One of my favorite places to study is Lake Suwa in Japan, where 15 generations of Shinto priests have maintained an ice record since 1443. That lake failed to freeze just three times in the first 250 years of its record. And since 1950, it has failed to freeze one out of every four years. Since 1990, it's only freezing twice a decade. And we projected that it may lose ice cover permanently by 2040.
In the Great Lakes region, we projected that some locations may lose ice cover by 2055 under high greenhouse gas emission scenarios, and 2085 if we reduce our emissions to a moderate level.
So the message here is, we’re losing our ice but there’s something we can do about it?
Yes. The silver lining there is that even a little bit of climate action has a big influence in regulating winter air temperatures and, in turn, ice coverage.
If carbon dioxide emissions started declining today (and we limit global air temperature increases below 2 degrees Celsius this century), only about 180 lakes out of those we studied would lose ice permanently this century. If we’re slower to act, we can still limit it to 430 lakes. But if we keep emitting greenhouse gases unchecked, we’ll permanently lose ice on thousands of lakes.
Which Great Lakes water bodies are in danger of losing their ice cover?
We looked specifically at harbors that have data going back to the 18th century. So for Lake Superior, we looked at Bayfield Bay in Wisconsin. And then for Lake Michigan, we looked at Grand Traverse Bay. And in both of those bays, we’re already seeing signals of a warming climate.
Bayfield Bay froze every year until the 1990s. But in the last 20 years, it has failed to freeze over several times. Grand Traverse Bay had very few ice-free winters before the 1960s, and it has experienced them regularly since then. So the data is telling us that not only is there warning on the horizon, there's warming in our past and present.
Can we assume other places in the Great Lakes will become permanently ice free?
Yes. Deep Great Lakes bays will see ice reductions, but places that are shallower or more protected will freeze more easily.
What are the human impacts of these changes?
For one, more people will drown. In a separate study, my team documented over 4,000 winter drownings across 10 northern countries, and we found that there were more winter drownings in warmer winters.
We also did a study looking at recreational activity, like ice fishing tournaments in Minnesota, skating races in Sweden, and ice roads (seasonal roads forged across frozen lakes and rivers) in Canada. We found that there were more cancellations of these events in warmer winters, and the ice roads opened much later.
One of these tournaments can bring in $800,000 of revenue to a small town in a week. So that’s a huge potential economic and cultural loss. And that’s not to mention the ecological effects of climate change, which other scientists have documented extensively.
So what is the lesson here for Michigan residents who cherish their cold, icy winters?
We need to start adapting to change. If you went ice fishing every Christmas or March break, that might not be possible anymore. We’re going to have to be flexible.
We also need to understand the importance of mitigating greenhouse gas emissions. It’s no secret that if the temperature is too warm, the water is not going to freeze. The only way to slow these temperature increases is to mitigate our greenhouse gas emissions.
The Great Lakes News Collaborative includes Bridge Michigan; Circle of Blue; Great Lakes Now at Detroit Public Television; and Michigan Radio, Michigan’s NPR News Leader; who work together to bring audiences news and information about the impact of climate change, pollution, and aging infrastructure on the Great Lakes and drinking water. This independent journalism is supported by the Charles Stewart Mott Foundation.