How warmer winters are making 'potentially unstable and unsafe' skating conditions on icy lakes

Lacing up skates to hit the ice on any one of Canada's lakes may be a common winter pastime for some, but a new study suggests it may be increasingly "potentially unstable and unsafe" to play a game of pick-up hockey on the frozen water.

On Thursday, York University shared the results of a new study that revealed the warmer winter weather has impacted the quality of the lake ice. When rivers and lakes freeze over, two types of ice layers form: black ice, which is clearer and denser due to fewer air pockets and larger ice crystals, and white ice, which is opaque like snow and filled with more air bubbles.

Due to the impacts of climate change, and when winter temperatures go above 0 C, and it rains during these traditionally colder months, the study found that total ice thickness has been getting thinner over time and less black ice is being formed – making it unstable to carry someone atop the lake.

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"The issue becomes that white ice is about half the strength of black ice, and so it becomes less safe for human use," York University professor Sapna Sharma told CP24 on Thursday morning.

According to the study's lead author, Joshua Culpepper, the combination of the thinner layers of black ice and the thicker layers of white ice make for "treacherous" conditions for skaters, snowmobilers, ice fishers and ice truckers alike.

"We know that in general, lake ice is forming later in the season and breaking up earlier, which implies an overall shorter duration of ice cover, but our study looked at what the ice is doing. How is it changing? You might get periods of time when people are on the ice and they think it's safe, but it really isn't. It's not sufficiently thick enough given the changes in the quality," Culpepper said in the study.

Ice thickness does not indicate safety

In mid-February and early March, the study's researchers had to halt ice measurements on Lake Simcoe and Point Lake since the ice cover was dangerously thin.

The study's authors say thickness alone is no longer a good indicator of how safe the conditions are before hitting the lake because if there is more white ice, there may not be enough support to carry a person's weight.

"Because of climate change, the ice core is less likely to be black ice, so we advise 20 centimetres if your ice core is made of white ice conditions should be your minimum before you go out on a lake or a river," Sapna said, adding it's best to go in a group and keep an eye out for warning signs regarding the ice's safety.

The study's authors note the "lack of consideration" for ice quality has caused deaths, noting findings from a 2020 study that determined northern Canada, particularly in the territories, saw the highest number of drownings per capita – despite being the coldest region of the country.

Last December, two teenagers in Ottawa – a 15-year-old girl and a 17-year-old boy – died after they fell through the ice on the Rideau River. The city had seen warmer-than-usual temperatures that month, with five straight days of above-freezing temperatures. Then, days later, in Sault Ste. Marie, a 58-year-old man died while skating, breaking through the ice in front of a home on Trout Lake.

These weakening ice conditions could also negatively impact more remote communities expecting critical deliveries of food and medicine, the study notes, as transport trucks need 100 centimetres of black ice.

"What we're predicting is a 95 to a 99 per cent loss in winter ice road transportation infrastructure without meaningful adaptations for ice safety," the study authors wrote in a news release issued on Thursday.

What struck to be the most surprising to Culpepper, however, is the lack of data analyzing lake ice quality.

"We were diving into what data was available, but trying to find exactly what we could work with in terms of data that's available in the Northern Hemisphere was pretty challenging," Culpepper said, adding that regularly conducted ice quality measurements are needed.

With files from CTV News Ottawa's Josh Pringle and William Eltherington