Warmer winters mean more ice-free lakes in the Northern Hemisphere, research shows

These ice-free years not only threaten the livelihoods of people who depend on them, but they can also have profound ecological consequences.

“Ecologically, ice acts as a reset button,” said Sapna Sharma, study co-author and associate professor in the biology department of York University in Toronto.

“In years you have no ice cover, the water temperatures are warmer in the summer. There is a higher chance of algae blooms, some of which are poisonous. And it can really affect spawning times and affect fish populations under the ice.”

There is also concern in the Arctic, where warming is happening three times faster than anywhere else in the world. And with more warming, there is more permafrost thawing, which can affect water quality in northern communities.

“One of the implications is for the hydrology of the region,” said Claude Duguay, a professor at the University of Waterloo and a university research chair in Cryosphere and Hydrosphere from Space, who was not involved in the study.

“When you have catastrophic drainage from these lakes, they naturally disappear. And they won’t necessarily reform as we reach higher temperatures. The impact for communities could be on food security. So you’re thinking about traps, hunting, fishing, as well as availability. of water for the communities. “

Of the millions of lakes in the world, the study suggests that more than 5,000 of them could be ice-free by the end of the century.

Dramatic changes

The authors found that ice-free years were more common in the second half of their study period. While there were only 31 ice-free events before 1978, there were 108 after that year.

One of the oldest records of lake ice is that of Lake Suwa near Nagano, Japan, which dates back to 1443, kept by Shinto priests. The study found that it doesn’t freeze annually, but now freezes an average of twice a decade.

“It could be the last time the lake ever freezes again in the next 10 years,” Sharma said.

These changes in the lakes, the authors say, are likely to persist for decades as the planet warms due to the continued release of greenhouse gases into the atmosphere.

The lakes most at risk are the ones that are deep because it is more difficult for them to form ice, particularly the Great Lakes, Sharma said.

And it’s not just about the quality of the water; it’s also about quantity, she noted. Ice helps reduce evaporation rate, so without that essential ice cover, evaporation rates can increase and decrease the amount of fresh water available.

Alex Mills, a professor at York University who studies ice phenology and was not involved in the study, has seen the change himself, especially on Lake Simcoe in Ontario.

“The general trend is pretty clear and it’s been since about 1850, the lake is now freezing about two weeks later than it used to, and it’s thawing about a week earlier than it used to,” he said. ‘And if you add those together, there is less ice on the lake here for about three weeks a year than before. So that’s quite a dramatic change. ‘

Mills said Barrie, a town that sits on the shores of Lake Simcoe, hosted an annual carnival in Kempenfelt Bay every winter until the 1970s. Then someone fell through “and that was it,” he said. “We’ve never had a carnival on the lake since then.”

While more lakes are likely to see more ice-free winters, Sharma said she believes with more research and solutions, there is still hope.

“I went to the [United Nations climate change conference] gatherings, and there are just so many young people who care about climate change, who dedicate their work to doing something about it. And people have very creative solutions, ”she said.

“I think in the next 20 or 30 years if we can get that support to know [the] the climate is changing and it’s affecting us now and we need to do something about it now – if we get people on board for that, I think we can change things. “