Climate change made B.C. heat wave more likely, researchers say

An unparalleled heat wave that paralyzed British Columbia last week was made 150 times more likely due to human-caused climate change, an international team of researchers said Wednesday.

A heat dome engulfing the Pacific Northwest from Oregon to B.C. spiked temperatures over 40 C in many communities. The town of Lytton set an all-time Canada-wide temperature record at 49.6 C. A day later, a wildfire ripped through the village, killing at least two people.

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Gonzales weather station in Victoria recorded an all-time-record high of 39.8 during the heat wave.

“The event was extremely rare. Our initial estimate is it was a one in a 1,000-year event in the present climate,” said Faron Anslow, a Victoria-based climate scientist from the Pacific Climate Impacts ­Consortium who collaborated on the study with 25 other ­scientists through the World Weather Attribution.

The team analyzed a vast quantity of historical temperature data going back to the 1800s. Then they ran climate models through over 4,000 simulations, tracing the likelihood of such an extreme event under different emission scenarios.

In the end, the study found the heat wave would have been “virtually impossible without human-caused climate change.”

Humans have already pumped enough carbon into the atmosphere to warm the planet by 1.2 C since the Industrial Revolution, according to the World Meteorological Agency. What happens in the coming decades depends on how fast the world’s economy moves away from fossil fuels and retains carbon-sucking ecosystems.

Under worst-case emission scenarios, the study found climate warming would lead to similar events every five to 10 years by the 2040s, when the world is expected to have ­undergone 2 C of human-induced warming. But even under a less extreme scenario, Anslow said the results were “pretty similar.”

“By the middle part of the century, we’re going to start to see these type of events,” he said. “We didn’t think we’d be here right now.”

So far, the B.C. Coroners Service has reported 579 more deaths across the province when compared to the five-year average over the same period.

Then there were the billion sea creatures thought to have baked to death along B.C.’s coast, and the yet-to-be-tallied crop failures that have left fruit shrivelled on trees and vines.

It’s that devastating climate fallout Anslow and his colleagues are warning about. “Is there something that the models don’t capture well? Or is there something fundamentally different with climate when it reaches a certain temperature? We don’t have those answers yet.”

By all indications, the heat wave was an exceedingly rare weather event, he said.

“There’s nothing about having an event like this that makes it more likely tomorrow,” he said. “The odds still are one in a 1,000 for any given year, until we know otherwise But certainly, as we get out into the 2040s, we’ll very likely be seeing these ­happening again.”

Co-author Kristi Ebi of the University of Washington said heat waves will be a major public health issue as climate change continues. The toll includes health problems and deaths directly related to heat as well as other conditions such as heart problems or respiratory diseases that are worsened by it.

“Almost all of the deaths are preventable,” she said. “People don’t need to die in heat waves.

“The possibilities for prevention are critically important to address.”

The study brought together 27 scientists from eight countries. Although it has not yet been published, the authors say it will be submitted for peer review and publication in the near future. Scientists used to be reluctant to link climate change with any specific weather event, that has begun to change.

— With The Canadian Press

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