Unfightable fires, wildfires that make their own weather and other terrifying trends scientists have observed

30 October 2023

Published by: https://www.thestar.com

GLOBAL – Over the last decade, the devastation caused by wildfires in Canada has been unprecedented, and 2023 is looking to be another record-breaking year.

In B.C., more area has been burned by wildfires in the last seven years than in the previous 58 years, and the province has recorded all of its worst four years on record since 2017, said Mike Flannigan, professor of wildland fire at Thompson Rivers University in Kamloops, B.C.

As the country comes to grips with what scientists say is a new normal, here are five things they’ve learned or observed in recent years that in some cases surprised even them.

There are wildfires in places there weren’t before

The scale of destruction caused by wildfires is happening sooner than scientists projected and in areas where it’s far less common. One recent example of this is the wildfire that swept through Maui, Hawaii last month, which left 97 people dead.

While that area has seen wildfires before, they didn’t have the fire management experience or labour force to fight a fire of that scale.

“That scale of fire really caught people off guard. But I think the point taken is that we are starting to see fire in places where we don’t normally see fire, or don’t see fire at all,” Flannigan said.

“And the 2019-2020 fires in Australia, were burning into tropical forests, which to anyone’s knowledge never burned before,” he added. “Because things have changed so dramatically.”

In B.C., Flannigan said they’re seeing more fires on Vancouver Island, which is home to temperate rainforests, as well as on the coast, which is atypical.

Robert Scheller, a professor in the department of forestry and environmental resources at North Carolina State University, said he wasn’t expecting to see what’s happening in California until the 2050s.

“Climate change is changing the baseline. I think what we’re seeing is more and more fires happening in what I call fire naïve communities,” Scheller said.

“As climate changes keep accelerating and these things start happening in more and more populated areas, my forecast is we’re going to be seeing many more unpleasant events,” he added. “In the immediate future and over the next decades. This isn’t going to slow down in my lifetime.”

In some cases, the science can’t keep up, he added. He said there is scientific uncertainty because the climate and the associated fire risk is changing faster than the research can catalogue it.

Studies examining the causes and impact of a single extreme weather event can take years. Now it seems like rare events that were anticipated once every 10 or 50 years are happening annually in different parts of the world, at a pace which makes it difficult for scientists to fully understand them, Scheller said.

“The gap between what we know and what we need to know has widened, a lot,” he said. “It feels like it’s somewhat accelerated a lot faster than we thought it was going to. And so that leaves us behind the eight ball, where we’re kind of struggling to keep up with the data.”

Some fires are insuppressible

There is a common perception that when a big wildfire is out of control, governments need to throw everything they have at it to get it under control. But we’ve now reached a point where all the manpower and technology we have can’t hold a candle to the sheer scale and intensity of some fires.

The intensity of wildfires is measured in kilowatts per metre of fire line. At above 4,000 kilowatts, it’s too hot and dangerous to have people in front of the fire. At 10,000 kilowatts, even aerial attack with the most expensive and high capacity airplanes becomes ineffective, Flannigan said.

These days, there are fires that reach 100,000 kilowatts per metre.

Flannigan said trying to put out these fires with aerial attack is ineffective because the water evaporates before it even hits the ground.

“It’s basically wasting your money. Almost every agency does it. And the optics are fine, but it doesn’t mean anything … it’s like spitting on a campfire,” he said.

In some cases, the walls of smoke are so thick personnel can’t get close enough to the fire to even attempt extinguishing it.

The potential destruction these fires can cause is compounded by the fact that we don’t have the manpower or technology to respond to them.

“What is concerning is, if this does come to reality, and maybe it’s coming much quicker than we anticipated, it means that fire management’s ability to extinguish fires is gonna become really challenging,” Flannigan said.

Floods and fires are linked

Fires leading to floods may not seem intuitive, but scientists say the frequency, intensity and duration of wildfires are making catastrophic floods more likely in certain areas of Canada.

It comes down to a phenomenon known as hydrophobic soil, or water repellent soil. It can have different causes, but in this instance it’s caused by the ash from fires carrying burned plant materials such as tree sap and debris. The organic material builds up the surface of the soil and creates a waxy coating that prevents the soil from absorbing water.

“It’s almost like concrete,” Flannigan said. “Instead of the tree canopies intercepting the rain and the roots and organic material on the forest floor sucking up the moisture, it just flows down the hill.”

The decreased soil absorption leads to increased overland and stream flow and increased runoff clogs stream channels which all contributes to greater likelihood of flooding.

This happened during the atmospheric river event in B.C. in November 2021, where torrential rain caused mudslides and flooding along Highway 5, leading to sections of the highway collapsing. The event ultimately caused about $1 billion in damages and left at least five people dead.

These hydrophobic soils can persist for years, making recently burned areas much more susceptible to flooding.

Fires can create their own weather

The types of megafires we’re seeing in parts of Canada can create their own weather systems, which are known as fire-generated thunderstorms or pyroCb (pyrocumulonimbus) clouds. Essentially, the energy from the fire creates convection which forms into clouds that can bring water and hail, but also more lightning strikes.

“In the fire and the combustion process, there’s heat, but there’s also moisture being released. It’s almost like you’re going through the water cycle, air rises, cools, condenses, forms clouds and that eventually develops into a thunderstorm,” Flannigan said.

The lightning that is created from these weather systems is a particularly vicious cycle, as it can generate more fires. That happened in Fort McMurray in 2016, where a fire-generated thunderstorm started four new fires. More recently, the Sparks Lake fire in B.C. in 2021 created approximately 7,000 lighting strokes and 40 new fires.

Flannigan wrote a paper about fire-generated thunderstorms in 1986, but said back then “it was really quite rare.”

In 2021, there were more than 100 fire-generated thunderstorms globally, about half of which were in Canada, Flannigan said. That was the previous record year for pyroCbs; it’s already surpassed by 2023. Canada has seen about 120 to 130 fire-generated thunderstorms this year alone, Flannigan estimated.

Megafires aren’t being driven by arson

Large wildfires, especially when they’re burning close to cities, are often blamed on people deliberately starting them. The frequency of extreme fire events has led to conspiracy theories about “eco-terrorists” igniting fires to drive fear about climate change.

In Canada, about 50 per cent of wildfires are started by lightning and 50 per cent are caused by human activity, Flannigan said. But only about two to three per cent of those human-caused fires were sparked by arson.

“They’re really blown out of proportion. About 50 per cent in Canada are started by lightning, but they’re responsible for 80 to 90 per cent of the area burned. So human caused fires are going down,” thanks to measures such as fire education and fire bans, Flannigan said.

This means that most of the destruction caused by fires in remote parts of Canada isn’t caused by humans, but by more lightning, higher than average temperatures and dryness, which most scientists agree are being driven by climate change.

Another misconception is how fires reach areas that are highly populated, Flannigan said. Fires that are started within cities are usually extinguished quickly.

“Fire harms a community through a rain of burning embers, generally not through the fire front,” Flannigan said. “And these embers can travel long distances, as we’ve seen recently in Kelowna, where it jumped the lake.”

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