An unprecedented and dangerous heat wave continues to scorch Western Canada and the Pacific Northwest in the U.S., with temperatures obliterating records that had been set just the day before.
The small community of Lytton B.C. set a new all-time Canadian heat record for the second day in a row on Monday. And in some cases temperatures have been close to 20 C above normal, shattering more than 70 temperature records in British Columbia and Alberta on Sunday alone.
“It’s something as a meteorologist I’ve just never seen before,” said Anthony Farnell, chief meteorologist for Global News. “I think undeniable that there is a linkage to climate change.”
The unseasonably hot weather has many asking whether the heat wave is a mere one-off or can be attributed to climate change. Climatologists are typically wary of trying to attribute any specific extreme weather event to climate change — although the evolving field of event attribution is beginning to change that.
“Weather-wise, the current heat wave in the west is due to a “heat dome,” Farnell explained.
“It’s a large area of high pressure that extends well up into the atmosphere. So in B.C., even at the top of the Rocky Mountains, the temperature is some 15 to 20 degrees above normal,” he said. “So when you have this dome, this high-pressure system, it’s a lot of sinking air underneath that just warms more as it comes down towards the coast.”
On top of this, the sun is shining day after day, and creating a bubble where the jet stream can do nothing but go around it, Farnell said. This stops the rain from coming in or cold fronts from cooling things down.
Although heat domes are nothing new, he explained that the frequency and duration in which they are happening could be attributed to climate change.
Globally, the world’s average annual temperature is one degree Celsius warmer than it was a century ago, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).
The 10 warmest years on record have all occurred since 2005, and seven of the 10 have occurred just since 2014, NOAA reported.
While a single isolated event might be normal, there’s little doubt that the world and Canada are together seeing more extreme weather events – patterns that can be attributed to climate change, climate scientists have previously said.
“We’re now in a climate where these kinds of extreme events are much more likely and much more severe,” Stanford University climate scientist Noah Diffenbaugh told Global News. “And the conditions right now …. in B.C. and Oregon and Washington and Northern California … are a great example.”
'A fingerprint of climate change'
One of the signs that Western Canada’s heat wave can be attributed to climate change is the high overnight temperatures, Simon Donner, a professor at the University of British Columbia’s geography department, told The Canadian Press.
Temperatures in B.C. are forecast to be higher overnight than they would normally be during the day for this time of year.
The average daytime high for this time of the year in B.C. is usually around 22 C, but the mercury is forecast to touch 34 this week, he said. More importantly, Donner said, the overnight low is projected to be 24 C, which is two degrees higher than the usual temperature during the daytime.
“That’s how unusual this is,” he said.
“It’s going to be warmer overnight than it usually is in the middle of the day.”
Donner said warming nighttime temperatures are “like a fingerprint of climate change.”
Another sign of climate change is the frequency and duration of the heat wave — a very dangerous combination, especially to vulnerable people.
For example, more than 25 people have died in the past 24 hours in Burnaby with the heat wave believed to be a contributing factor according to local RCMP.
“We are seeing this weather can be deadly for vulnerable members of our community, especially the elderly and those with underlying health issues. It is imperative we check on one another during this extreme heat,” Cpl. Mike Kalanj with Burnaby RCMP said.
Farnell said when this type of severe heat persists for more than a week, “it takes a toll on our bodies.”
He added that the weather in B.C. may not be “completely” linked to climate change, as there’s “obviously natural variability in there.”
“But it’s a sign that we’ve been looking out for. A lot of scientists have been saying these events are becoming more severe and more frequent. And it just happens to be over B.C. this time around.”
He said he wouldn’t be surprised if the region gets hit with another heat dome before the summer ends.
Diffenbaugh agreed, adding there is “a lot more evidence” suggesting that when these weather patterns occur, they create more severe heat with increasing frequency.
“It is very clear that California and much of Western North America are in a new climate, it’s a climate that continues to change,” he said. “Where we have more dry periods and more severe drought and more severe wildfire conditions.”
And these periods of heat severe heat are also punctuated with wet conditions, which provide more runoff and flood risk.
For example, on Sunday, an evacuation order was issued for parts of Pemberton Valley in B.C. amid rising floodwaters. It comes amid rapid snowmelt, hastened by blistering heat in the region.
Not just in western Canada
The extreme heat wave seen in B.C. is not just tied to that region. It’s still been very hot and humid in Ontario, Quebec and Atlantic Canada, Farnell said.
“And even though there’s not a direct relation to that heat dome, it’s still a hot period that we’re all having to deal with as Canadians,” he noted.
And it may just get warmer from coast to coast.
Between 1948 and 2016, the best estimate of mean annual temperature increase is 1.7 C for Canada as a whole and 2.3 C for northern Canada, according to Canada’s Changing Climate Report, released in 2019.
And temperatures will continue to rise, reaching more than 6 C by the late 21st century if carbon emissions aren’t lowered, the report warned.
“The effects of widespread warming are evident in many parts of Canada and are projected to intensify in the future,” the report stated. “In Canada, these effects include more extreme heat, less extreme cold, longer growing seasons, shorter snow and ice cover seasons, earlier spring peak streamflow, thinning glaciers, thawing permafrost, and rising sea level.”
The second landmark report, released just days ago, only affirmed the risks of rising temperatures in Canada and globally, warning how a warming planet will impact everything from infrastructure to tourism and geopolitics — and it’ll come at a hefty cost.
The Paris climate change agreement Canada signed in 2015, with the rest of the world, aims to keep global warming at 2 C compared to the pre-industrial level — but 1.5 C would be even better, scientists say.
“Even if the Paris agreement is successful, holding the global temperature below two degrees is still more global warming and climate change than we have already had,” Diffenbaugh said.
However, failing to hit these emission goals means it could be three degrees of global warming or even more, resulting in even more severe heat than we are seeing now, he said.
“Dealing with climate change means finding ways to supply the energy needs of the world while also eliminating the amount of global warming, like reducing emissions,” he added.
–With files from Global News’ Simon Little and The Canadian Press
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