Warmer winter temperatures are shortening Canada's outdoor skating season and may eventually prevent ice from freezing on backyard rinks that helped shape its greatest hockey stars, a new study warned Monday.

This past winter warmer-than-usual seasonal temperatures forced a late opening and early closure of outdoor rinks across the country, affecting thousands of skaters and hockey players.

"I went to the rink only eight times this year, compared to about 20 times or twice a week in past years," huffed Guillaume Bilodeau, 30, shooting pucks into an empty net at an outdoor rink in Montreal's Petite Patrie neighborhood.

Because the ice was soft, cracked and missing in spots, he did not even lace up his skates.

"This year the season started at the beginning of January and for the past two or three weeks it's only been so-so," he said. "And now it's already on its last legs."

In the capital Ottawa, the 7.8 kilometer (4.8 mile) Rideau Canal Skateway through downtown was open only 28 days, marking one of its worst seasons in 42 years.

In Winnipeg, half of its river skateway remained closed all winter as part of the Assiniboine River did not freeze over.

And it will only get worse, according to researchers Nikolay Damyanov and Lawrence Mysak of McGill University and Damon Matthews of Concordia University in Montreal.

The trio published a study in the journal Environmental Research Letters that showed "a statistically significant decrease in the length of the skating season" in many parts of Canada over the past half century.

They calculated the annual start date and length of the outdoor skating season from historical weather data across Canada and recorded how these have changed since the 1950s in tune with global warming.

A high temperature of minus five Celsius (23 Fahrenheit) over three days, enough to lay the initial ice on a rink, signaled the beginning of an area's outdoor skating season.

Data from 142 meteorological stations showed the largest decreases in the skating season length in the Canadian Prairies and southwestern regions.

By extrapolating their data to predict future patterns, the researchers also envisaged a complete end to outdoor skating within the next few decades in westernmost British Columbia and Alberta provinces.

"There will be no days that are cold enough to flood a rink by mid-century over most of southern Canada," Matthews told AFP, adding cities such as Calgary, Montreal and Toronto would have to artificially freeze ice to offer outdoor skating.

The study notes that hockey legend Wayne Gretzky, like many Canadians, started skating as a child on a rink in his backyard.

"It is hard to imagine a Canada without outdoor hockey," said Matthews. "But I really worry that this will be a casualty of our continuing to ignore the climate problem and obstruct international efforts to decrease greenhouse gas emissions."