What does a 1.5 C increase in global temperatures mean for Canada?

A report from the World Meteorological Organization suggests there is a two-in-three chance global temperatures will temporarily exceed a 1.5 C increase above pre-industrial levels within the next five years.

That 1.5 C benchmark matters because it’s what the 2015 Paris Agreement and subsequent climate accords have set as a threshold to limit the most catastrophic impacts from climate change.

The WMO is “sounding the alarm” over the increase; every fraction of a degree that global temperatures rise, losses and damages are expected to mount.

But Canada, especially polar 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 temperature in the country rose by 1.9 C from 1948 to 2021.

Experts say the significance 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 temperatures may cross and fall back under the 1.5 C threshold over the next several years.

This forecast is a significant departure from 2015, when the WMO says the chance of exceeding 1.5 degrees 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 pre-industrial level,” he said.

Djordje Romanic, assistant professor at McGill University’s Department of atmospheric 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 because it’s already been exceeded in Canada, says Zwiers, especially since Canada’s temperature is increasing roughly twice as fast as the global average.

“There’s a lot of fluctuation 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 normal on Canadians?'” Zwiers said, noting that some expected outcomes may include more frequent and extensive heat events, increased losses of glaciers, and changes to wildlife habitats and habits.

Rising temperatures are also partly to blame for the elevated risk of wildfires across much of Canada, says Zwiers.

McGill’s Romanic notes that trends in temperatures vary drastically across different regions. For instance, despite northwestern Canada’s relatively small population and few total emissions, research suggests the region may be subject to the greatest variation in weather conditions.

Temperatures are rising at an even faster rate across Canada’s North, where permafrost frozen for thousands of years is now thawing and critical transportation infrastructure is being put under threat — in Yukon, warmer winter temperatures are disrupting access between communities.

The Northwest Territories implemented a heat-warning program in 2017 to warn of extreme heat during the summer — the province has already warmed between 2 to 4 degrees since 1950.

“People that don’t contribute much might suffer more than people that contribute more, because the atmosphere 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 extreme weather.

“To prevent further rises in global mean temperature, you really have to substantially 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 overhaul of many sectors, including a 42 per cent cut in oil and gas sector emissions.

It’s not an easy task, says Zwiers.

“I think what we can possibly achieve as a global society is stabilized global mean temperature 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.”