Severe wildfires the new normal due to climate change, B.C. fires contribute to floods: study

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With some of the world’s worst fire years happening in the last decade, Canadian scientists say severe wildfires are part of a “new reality” caused by climate change, and are at least partly behind floods like those that recently devastated British Columbia .

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Extreme conditions like lower humidity and higher temperatures are driving extreme wildfires and make them more likely to happen, researchers found in study published Thursday involving former University of Alberta fire expert Michael Flannigan. Scientists found eight of the world’s worst fire seasons happened in the past decade, and five of B.C.’s worst seasons in the past five years.

The study found increases in extreme weather can cause major fires including in Northern Canada and B.C. Flannigan says globally, weather patterns that make fires worse has become more common in the last 40 years, even more so in the last two decades.

“It’s not a big surprise, but with climate change, we expect warmer conditions to continue and this trend to continue, expand and get worse,” Flannigan said in a University of Alberta news release.

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For the study, researchers looked at extreme fire weather trends from 1979 to 2020, including the intensity, rate of spread, and changes in humidity.  Decreasing relative humidity drove more than three-quarters of rising fire intensity and spread, and increased temperatures were behind 40 per cent of the trends.

The results link global warming and changes in humidity to the likelihood extreme fires will happen more frequently, spread to new areas, and burn more intensely than in any previous time in world history.

More fires also mean Canadians will need to live with the consequences of them.

For instance, B.C.’s wildfires are likely a factor in intense flooding that recently washed out and destroyed major roadways, Flannigan said.

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“It is not all attributable to fires, but fires do play a role. When you remove the vegetation, the rain is not being intercepted by the trees, the roots aren’t picking up the moisture, there is nothing to give the soil stability — you’re much more likely to see land and mudslides in burnt areas,” he said. “This has been documented in California for years.”

Flannigan said communities need to prepare for the consequences of fire because even if global warming stopped today, the threat would continue for decades.

“We’re on this path of a new reality. It’s not normal because there’s nothing normal about what’s going on,” he said.

The study, “Observed increases in extreme fire weather driven by atmospheric humidity and temperature,” was published in Nature Climate Change this week.

lboothby@postmedia.com

@laurby

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