What does a 1.5 C increase in global temperatures mean for Canada?
A report from the World Meteorological Organiza‐ tion suggests there is a two-in-three chance global temperatures will tem‐ porarily exceed a 1.5 C in‐ crease above pre-industrial levels within the next five years.
That 1.5 C benchmark mat‐ ters because it's what the 2015 Paris Agreement and subsequent climate accords have set as a threshold to lim‐ it the most catastrophic im‐ pacts from climate change.
The WMO is "sounding the alarm" over the in‐ crease; every fraction of a de‐ gree that global temperatures rise, losses and damages are expected to mount.
But Canada, especially po‐ lar regions that are warming the fastest of all, has already blown past 1.5 degrees of warming over pre-industrial levels.
According to Environment and Climate Change Canada, the average annual tempera‐ ture in the country rose by 1.9 C from 1948 to 2021.
Experts say the signifi‐ cance in Canada of passing this global threshold may be difficult to determine, given the warming here already — but it isn't good.
Breaching 1.5 C
While the world may breach the 1.5 C limit within the next five years, the World Meteorological Organization notes the increase isn't a straight line — annual tem‐ peratures may cross and fall back under the 1.5 C thresh‐ old over the next several years.
This forecast is a signifi‐ cant departure from 2015, when the WMO says the chance of exceeding 1.5 de‐ grees warming globally had been close to zero.
Francis Zwiers, director of the Pacific Climate Impact Consortium at the University of Victoria, says it's likely the world will reach a point where temperatures are consistently above that threshold.
"It might take more than a few years, but eventually we're going to be in a state where every year will be above 1.5 degrees above preindustrial level," he said.
Djordje Romanic, assistant professor at McGill Universi‐ ty's Department of atmos‐ pheric and oceanic sciences, says it's important to keep longer-term trends in mind.
"Year to year there are very large oscillations," he said. "So in order to surpass that limit we have to look at climatological periods, which are 30 years at least." Canada's temperature The 1.5 C global threshold shouldn't be ignored just be‐ cause it's already been ex‐ ceeded in Canada, says Zwiers, especially since Cana‐ da's temperature is increasing roughly twice as fast as the global average.
"There's a lot of fluctua‐ tion from one year to the next, but we've been warming pretty rapidly," said Zwiers.
"You need to start thinking about, 'What are the impacts of three degrees above nor‐ mal on Canadians?'" Zwiers said, noting that some ex‐ pected outcomes may include more frequent and extensive heat events, increased losses of glaciers, and changes to wildlife habitats and habits.
Rising temperatures are al‐ so partly to blame for the ele‐ vated risk of wildfires across much of Canada, says Zwiers.
McGill's Romanic notes that trends in temperatures vary drastically across differ‐ ent regions. For instance, de‐ spite northwestern Canada's relatively small population and few total emissions, re‐ search suggests the region may be subject to the great‐ est variation in weather con‐ ditions.
Temperatures are rising at an even faster rate across Canada's North, where per‐ mafrost frozen for thousands of years is now thawing and critical transportation infra‐ structure is being put under threat — in Yukon, warmer winter temperatures are dis‐ rupting access between com‐ munities.
The Northwest Territories implemented a heat-warning program in 2017 to warn of extreme heat during the sum‐ mer — the province has al‐ ready warmed between 2 to 4 degrees since 1950.
"People that don't con‐ tribute much might suffer more than people that con‐ tribute more, because the at‐ mosphere doesn't care," he said.
So what now?
While crossing the global threshold of 1.5 C warming is likely in coming years, it's not a switch where climate goes from comfortable to crisis.
Experts point out that every degree, and fraction of a degree matters, in terms of turning up the dial on wildfire risk, heat waves and other ex‐ treme weather.
"To prevent further rises in global mean temperature, you really have to substantial‐ ly reduce greenhouse gas emissions and get to a point that we call 'net zero,'" Zwiers said.
Canada's goal is to reach net zero carbon emissions by 2050, which requires an over‐ haul of many sectors, includ‐ ing a 42 per cent cut in oil and gas sector emissions.
It's not an easy task, says Zwiers.
"I think what we can possi‐ bly achieve as a global society is stabilized global mean tem‐ perature at a new level, but we're going to have to, we're going to have to learn via adaptation to live with that new level, unfortunately."
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