How global warming is reshaping winter life in Canada


H. Damon Matthews, Concordia University and Mitchell Dickau, Concordia University As we begin to emerge out of yet another mild winter, Canadians are once again being reminded of just how acutely global warming has changed Canada’s winter climate.

The impacts of this mild winter were felt across the country and touched all aspects of winter culture. From melting ice castles at Québec’s winter carnival, to a dismal lack of snow at many Western Canada ski resorts, seemingly no part of Canada was unaffected. But the change that will likely be felt most keenly by many Canadians is the loss of a reliable outdoor skating season.

For the second year running, Ottawa’s Rideau Canal Skateway was closed for what should be the peak of the skating season. In 2022-2023, the Skateway did not open at all for the first time ever. This winter, a portion of the Skateway opened briefly in January, but continuing mild temperatures forced a closure again after only four days of skating. In Montréal, fewer than 40 per cent of the city’s outdoor rinks were open in the middle of February.

There is no obvious upside to this story. Outdoor skating in Canada is fast becoming the latest casualty of our failure to confront the reality of the climate crisis.

On thin ice

More than a decade ago, our research group published our first analysis of how outdoor skating was being affected by warming winter temperatures in Canada. We showed that even as of 2005, there was already evidence of later start dates, and shorter skating seasons across most of the country.

A report on the management of the Rideau Canal Skateway in 2023, produced by the CBC.

These conclusions were echoed by subsequent publications from the RinkWatch project, which has reported consistent declines in skating season length and quality in many Canadian cities.

Meanwhile in Ottawa, skating days on the Rideau Canal Skateway have been trending downwards over the last 20 years. In this time, the typical skating season has decreased by almost 40 per cent, a trend that is clearly correlated with increasing winter temperatures over the same period.

Moving in the wrong direction

Climate mitigation progress continues to be far too slow.

Global CO2 emissions reached their highest level ever recorded in 2023, and average global temperatures have now reached 1.3 C above pre-industrial temperatures. If these trends continue, we are on track to reach 1.5 C — the lower threshold of the Paris Agreement temperature target — in less than seven years.

In our 2012 paper, we estimated that suitable rink flooding days could disappear across most of southern Canada by mid-century. In a more recent analysis of Montréal’s outdoor rinks, we estimated that the number of viable skating days in Montréal could decrease to zero by as early as 2070.

In hindsight, these and other similar projections may have been far too optimistic. In a study of Rideau canal skating days published in 2015, the authors projected declining but sustained skating conditions throughout this century, even in a high future emissions scenario. The reality of the past two seasons shows that skating conditions have deteriorated far more quickly than predicted.

Global temperatures in 2023 were the highest ever recorded, as were winter temperatures in December 2023 and January 2024. Since 1950, winter temperatures in Canada have increased by more than 3 C, which is about three times the rate of global warming over this same period.

Outdoor rinks require at least three consecutive very cold days to establish a foundation of ice, followed by enough cold days to maintain a good ice surface. Temperatures above freezing are poorly tolerated by outdoor rinks, and rain is often disastrous.

A few degrees of warming in January and February temperatures can be the difference between a rink that is skatable and one that is not. As winters continue to warm, the case for building and maintaining outdoor municipal rinks will become harder to justify.

A stark and still changing new reality

As years go by without any real progress on climate mitigation, it is becoming increasingly difficult to imagine a future in which outdoor rinks will be widely available without artificial refrigeration. Other winter activities will also be affected by changing snow conditions, but outdoor skating will likely be hit first in direct response to warming winter temperatures.

Wayne Gretzky famously learned to skate and play hockey in Branford, Ont. in the 1960s on an outdoor rink built by his father. Reliable winter skating conditions in southern Ontario are already mostly a thing of the past, and are becoming more and more scarce as global warming progresses. It is increasingly unlikely that current and future generations will be able to follow Gretzky’s path.

This reality is both a tragic injustice for many young Canadians and an existential threat to a core aspect of the Canadian winter identity.

Preserving what remains of Canada’s winter skating culture will require that we rapidly step up our efforts to drive down CO2 emissions and stabilize global temperatures. Otherwise, Joni Mitchell’s “river I could skate away on” will become an increasingly wishful dream that soon will exist only in the lyrics of old songs.The Conversation

H. Damon Matthews, Professor and Climate Scientist, Department of Geography, Planning and Environment, Concordia University and Mitchell Dickau, PhD Candidate, Geography, Planning, and Environment Department, Concordia University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Polar bears may struggle to produce milk for their cubs as climate change melts sea ice

During their time onshore, polar bear mothers may risk their survival by continuing to nurse when food is not available. (Shutterstock) Louise Archer, University of Toronto

When sea ice melts, polar bears must move onto land for several months without access to food. This fasting period is challenging for all bears, but particularly for polar bear mothers who are nursing cubs.

Our research, published in Marine Ecology Progress Series, found that polar bear lactation is negatively affected by increased time spent on land when sea ice melts.

Impaired lactation has likely played a role in the recent decline of several polar bear populations. This research also indicates how polar bear families might be impacted in the future by continued sea-ice loss caused by climate warming.

Challenges of rearing cubs

While sea ice might appear as a vast and perhaps vacant ecosystem, the frozen Arctic waters provide an essential platform for polar bears to hunt energy-rich seals — the bread and butter of their diet.

Sea ice is a dynamic environment that can vary through time and in different regions of the Arctic. Polar bears in Canada’s western Hudson Bay area experience seasonal sea ice, which melts in the warmer summer months, forcing the polar bears to move onto land until cooler winter temperatures cause the sea ice to refreeze.

On shore, polar bears often remain in a fasting state, using their body stores of fat for fuel. (Shutterstock)

While on shore, hunting opportunities are rare and polar bears generally spend their time in a fasting state. Polar bears rely on their immense body fat stores to fuel them during these leaner months, with some individuals measuring almost 50 per cent body fat when they come onshore in early summer.

While on land, polar bears can lose around a kilogram of body mass per day, so making it to the end of the ice-free season requires them to carefully manage their energy. For most polar bears, this means reducing activity levels and conserving energy until the sea ice returns and seal hunting can resume.

Females with cubs must also factor in the additional burden of lactation. Polar bears produce high-energy milk, which — at up to 35 per cent fat — is like whipping cream. This high-fat milk allows cubs to grow quickly, increasing from just 600 grams at birth to well over 100 kilograms by the time they are around two-and-a-half years old and leave their mothers to become independent.

During the onshore fasting period, polar bear mothers face a difficult trade-off: Stop lactating and risk the health of her growing cubs or continue nursing and risk her own survival as her energy reserves are depleted.

Polar bear cubs remain with their mothers for up to two-and-a-half years. (Shutterstock)

Moderating lactation

Although lactation is important to both mothers and cubs, studies on polar bear lactation are relatively rare.

To better understand how females manage their lactation investment, our research team revisited a data set of polar bear milk samples collected in the late 1980s and early 1990s from polar bears on land during the ice-free period.

We estimated how long each polar bear mom had been fasting based on annual sea-ice breakup dates and found that the energy content of their milk declined the more days spent onshore. Some bears had stopped producing milk entirely. Both milk energy content and lactation probability were negatively related to the mother’s body condition, meaning females in poor body condition had to prioritize their own energetic needs over their cubs.

The bears who reduced their investment in lactation benefited by using up less of their body reserves, meaning they could fast for longer. Yet the cubs who received lower energy milk grew more slowly than offspring of females that maintained their lactation effort. In the long term, this may reduce cub survival and, ultimately, negatively affect population dynamics.

Climate change and population declines

After around three months on land, the probability of a female with cubs lactating was 53 per cent. This dropped to 35 per cent for a female with yearlings (older cubs from the previous year).

The data in our study were collected around three decades ago. Since then, climate warming has meant that the ice-free season in western Hudson Bay has been extending by around seven days per decade. Polar bears are now regularly forced to spend more than four months on land.

As the ice-free season has increased and polar bears must go for longer without food, their average body condition has declined. The ability of female polar bears to nurse their cubs has probably also become increasingly impaired.

This may have contributed to the 50 per cent decline in the population size of the western Hudson Bay population over the last four decades, and is likely to contribute to further declines if climate warming and sea-ice declines continue as projected without mitigation.

This research adds another piece to our understanding of polar bear resilience to climate change. Without action to halt climate warming and sea-ice loss, survival of cubs will be at risk across the Arctic.The Conversation

Louise Archer, Postdoctoral Fellow, Biological Sciences, University of Toronto

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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