AS THE GREAT CANADIAN WINTER APPROACHES, SOME CLIMATOLOGISTS ARE PREDICTING THAT ITS END MAY BE IN SIGHT. SCIENTISTS SAY WINTERS ARE EXPECTED TO GET WARMER AND SUMMERS SCORCHING. KIRKEY.
NEW MAPS PROJECT IMPACT OF CLIMATE CHANGE IN CANADA
Is this the end of the Great Canadian winter? A new report says that even if greenhouse gas emissions are reduced, all of Canada is projected to get warmer by the end of the century, while the number of 30C plus days per year are predicted to “explode” under the current global warming trajectory.
The report by climatologists at the University of Winnipeg-based Prairie Climate Centre looks at how temperature and precipitation are likely to change under two hypothetical warming scenarios: a “low-carbon” one that assumes emissions will slow, and a high-carbon scenario that assumes the opposite — “that humanity will continue to emit more and more greenhouse gases into the atmosphere well into the future.”
“It is of course urgently necessary that we reduce greenhouse gas emissions to prevent the most dire climate-change consequences, but we must also accept the reality that at least some climate-change impacts are all but guaranteed,” writes climate-change researcher Ryan Smith.
How much warmer and wetter will our future climate be? According to a series of maps produced by the Prairie centre climatologists: Under a high-carbon scenario, in some months the Arctic is projected to warm by more than 12 degrees Celsius by the end of this century. Sea ice and snow reflect unwanted solar energy back into space. Without it, the open ocean would absorb sunlight, speeding the rate of global warming. The months of December and January are projected to warm faster than the month of June.
Warmer winters might sound marvellous, but they make it easier for agricultural and forest pests to survive winter. Cold winters are also vital for winter roads relied upon by “tens of thousands of Canadians,” including First Nations. Southern Canada is expected to get wetter through the spring, fall and winter — increasing the risks of the kind of flooding that soaked swaths of Ontario and Quebec this year — but much drier in summer, increasing drought and wildfire risks.
The modelling was based on two 30-year future periods — 2021 to 2050, and 2051 to 2080, using 12 different climate models. The researchers used an average of the models.
Overall, the globe is projected to warm by two to three degrees Celsius by 2051 to 2080, compared to 12 degrees or more for some places in the Canadian High Arctic, assuming the highcarbon future we’re trending towards, Smith said in an email.
Toronto’s summers are projected to warm by four degrees Celsius by 2051 to 2080 in a high-carbon scenario; in comparison, its winters are projected to warm five degrees Celsius. Churchill summers will warm by 3.5 degrees Celsius; its winters by nine degrees.
While Vancouver, Toronto and Montreal are warming at a slower rate (at least compared to the Canadian Arctic), the warming is still “dramatic and worrisome,” Smith said. “Even a few degrees of average temperature change can lead to a drastic climate change.”
For example, Toronto currently averages 12 days per year that reach or exceed 30C. By 2051-2080, under the high-carbon modelling, that number is projected to rise to 55.
“Sometimes the ‘average mean temperature change’ can be very misleading, especially when we talk of only a few degrees of change,” Smith said. “The reality is that small changes in the mean add up to big changes in the extremes.”
Why is winter changing, and projected to change more? There’s an energy deficit during winter, Smith explained. Longer nights and shorter days mean energy is being lost to space. Greenhouse gases stop this escaping heat.
“More simply: we cool off at night, and nights are longer in the winter, and greenhouse gases prevent the planet from cooling off,” Smith said.
The less snow the less reflective the surface. “As soon as you get the snow cover gone, boom, it warms up really quickly, because the sun gets absorbed by the ground,” said Danny Blair, a University of Winnipeg professor of geography and director of science at the Prairie Climate Centre. “Winter, in our future, is going to be very different from the past,” he said. Winters will get not just warmer, but wetter.
The researchers were also struck by the projected average drying and warming in the summer months across the Prairies and into Alberta and B.C., with 20-per-cent drops in precipitation in some regions. “That spells trouble,” said Blair. Drought and forest fires “are even more so going to be a problem in our future.”
Under the high-carbon, far future scenario, the number of hot days “is just going to explode. It’s scary,” Blair said.
Near the end of the century, summers in southern Ontario will have, on average, more than 80 days of 30C plus — the climate of Nebraska or northern Texas.
The Prairie Climate Centre is a collaboration of the University of Winnipeg and the International Institute for Sustainable Development.