More and more Canadian municipalities will be faced with the decision whether to permanently close natural outdoor rinks because of warmer winter temperatures, says one environmental studies professor.

Robert McLeman's comment Thursday came after the City of Montreal announced the closure of the popular Beaver Lake rink.

"Climate change is a reality now and what we're seeing with Beaver Lake is just one of the smaller but significant impacts of this trend of warming temperatures (and) milder winters," the Wilfrid Laurier University professor said in an interview.

"It's moving most quickly in southern Ontario, Quebec and into the Maritimes and a little bit slower out West."

Skating on the historic Beaver Lake rink was a popular winter pastime for decades but the city is shuttering the facility because of climate change and constantly shifting winter temperatures that make it impossible to keep the surface safe.

"With global warming, we had a terrible year last year in terms of ice melting," said Luc Ferrandez, who oversees parks and greenspace on the city's executive committee.

"In fact, it was the worst year ever --we went from 100 days of opening per year to 37."

Many days when the rink was open, conditions weren't ideal and city vehicles that were used to maintain the ice would occasionally fall through.

"We can't afford that kind of risk on Mount Royal," Ferrandez said, adding snow is being left on the ice to keep people off.

The rink did not open this season.

McLeman is co-founder of RinkWatch, a research project Wilfrid Laurier launched five years ago to monitor long-term impacts of climate change by studying ice rink data from across North America.

His colleagues took some of the collected data and put it into a climate model to forecast future skating seasons.

"What we've seen is in Montreal, for example, in the second half of this century (after 2050), skating season will shrink by probably a third, maybe up to 40 per cent," McLeman said. "Out West, say Calgary for example, it would be about 20 to 25 per cent."

It leaves many municipalities with a hard choice: maintain outdoor rinks with shrinking seasons or spend big on expensive refrigerated rinks and indoor arenas.

An outdoor rink requires an average daily temperature of -5 C to be maintained.

"Even at -4 C, you won't be able to skate on it," McLeman said.

"Which is what creates that paradox: it's still cold and below freezing outside but it's not cold enough to have a rink and that's sort of the type of regime we're moving into with climate change."

Further complicating problems in Montreal was that in 2012, the city started a three-year project deepening Beaver Lake, an artificial basin, to about seven metres -- a process that has made it even harder to make a proper rink.

Ferrandez said lowering water levels as proposed by one community group would make it too steep for skaters and make it more difficult for maintenance equipment to reach the ice.

A smaller refrigerated ice rink near the chalet on Mount Royal remains open.

Mayor Valerie Plante said she was disappointed with the closure, but called the decision a security issue.

Ferrandez said it's a priority for the administration to find a new site on the mountain for a natural rink by next winter.

That, says McLeman, is good news for skating enthusiasts, as the experience is worlds apart from skating indoors.

"Absolutely not the same," he said. "For anyone who has skated outside on Beaver Lake or the Rideau Canal, there's no comparison."