BC Wildfire Service

How climate change is making B.C.’s wildfire season hotter, longer, drier

Scientists fear ‘vicious, vicious cycle’

Wildfires are wreaking havoc in British Columbia. Last year’s fire season was unprecedented: 1.2 million hectares burned in B.C., ten times the ten-year average.

As of Monday morning, there were more than 3,400 firefighters responding to about 600 wildfires in the province and more than 20,000 people impacted by evacuation alerts and orders. There are currently 46 fires of note in B.C., which the B.C. Wildfire Centre describes as fires “which are highly visible or which pose a potential threat to public safety.” More than 140 new fires in B.C. started on Sunday August 12th alone.

In 2017, fighting B.C. fires cost nearly $560 million and some 65,000 people were forced to evacuate.

The province issued a state of emergency in early July, then extended it — and extended it again and again — until it became the longest in B.C.’s history.

On average, 7,000 wildfires are sparked across Canada every year, burning through 2.5 million hectares — about half the size of Nova Scotia.

According to Mike Flannigan, a professor in the Department of Renewable Resources at the University of Alberta, this number has doubled since 1970.

“My colleagues and I attribute this to human-caused climate change,” he said. “I can’t be more clear on that. Human-caused climate change.”

There are a number of ways climate change increases the frequency and intensity of wildfires — including more severe droughts, declining snowpack, increasing incidence of thunderstorms and extreme heat exacerbated by rapid warming in the Arctic.

But wildfires themselves may also contribute to global climate change, meaning a dangerous trend is poised to only get worse.

“It’s a positive feedback loop,” Bob Gray, a wildfire ecologist based in Chilliwack, told The Narwhal. “Fires emit more greenhouse gases into the atmosphere, which in turn increases global warming. It’s a vicious, vicious cycle.”

‘The warmer it gets, the more fire we see’

Heat is widely regarded as one of the biggest contributors to a voracious wildfire season — and the headlines so far this summer have been all about heat, be it in Sweden, Algeria, California, Montréal or Japan.

Temperatures are on the rise around the world. Global data compiled by the U.S. National Oceanic and Atmospheric Administration indicates that the last 30 days have seen 3,210 new record daily temperatures.

Earlier this year, the World Meteorological Organization released its 25th annual Statement on the State of the Global Climate, noting that “the years 2015, 2016 and 2017 were clearly warmer than any year prior to 2015.”

In B.C., numerous heat records were broken across the province in July.

All this heat spells trouble for forests. “The warmer it gets, the more fire we see,” said Flannigan. “And this is true all over.”

The Government of British Columbia predicts that climate change will lead to a temperature increase of between 1.3 and 2.7 degrees by 2050, leading to droughts that are more frequent and more severe.

Droughts create tinderbox conditions

Droughts dry out the forest, meaning the forest floor is increasingly lined with dry, dead wood that is as combustible as a tinderbox. This dry material is known as fuel.

Fuel is one of the three ingredients needed for any wildfire, along with ignition (usually lightning or people) and weather.

When conditions are hot and dry, a strike of lightning or a carelessly discarded cigarette can be incendiary, and fire can rip through forests — quickly becoming a dangerous crown fire that burns from treetop to treetop.

Lightning strikes across Thunder Lake, Alberta. Photo: Tyler Balser

According to Flannigan, we can attribute some of the hot, dry conditions to the weakening of the jet stream — the air current that drives weather conditions in the northern hemisphere.

“In the northern hemisphere, the jet stream gets its energy from the temperature difference between Arctic areas and equatorial regions,” said Flannigan.

Climate change has resulted in air temperatures in the Arctic that are warming twice as fast as the rest of the globe, according to the 2017 Arctic Report Card.

“That temperature difference is getting smaller, so that means our jet stream is getting stagnant and it stalls,” Flannigan said. A weaker jet stream means hot and dry areas stay that way. The result has obvious implications for wildfires.

Higher temperatures = more lightning

But increased heat does more than just dry out fuels.

A 2014 study published in the journal Science predicted that for every one-degree increase in global temperature, there will be a corresponding 12-per cent increase in lightning strikes.

There are already tens of thousands of lightning strikes per day in B.C. — across the country, there were an average of 895,000 lightning strikes recorded every July between 1999 and 2013 — and more than half of wildfires in B.C. are ignited in this way.

“An increase in lightning ignitions in our hot dry summers is a serious situation,” said Lori Daniels, an associate professor in the Faculty of Forestry at the University of British Columbia. “And now we’re seeing that playing out.”

There are other factors at play as well, according to Daniels, including more nuanced changes in weather: higher average night-time temperatures, earlier springs and intermittent rain in the winter which reduces snowpack — all of which Daniels said we’ve seen in B.C. already this year.

“The bottom line is warmer temperatures mean that the fuels will be drier,” Flannigan said, “so it’s easier for fires to start, spread and to burn more intensely.”

Wildfires may further fuel climate change

As climate change increases the likelihood that wildfires will burn more often and over a bigger area, another concern looms large: researchers are finding that the wildfires themselves may be contributing to global warming.

Earlier this year, the government of B.C. released an independent report detailing what it dubbed “the new normal” of catastrophic natural disasters — namely floods and fires — which have been exacerbated by climate change. But the report also noted a disturbing trend in the greenhouse gas emissions of the wildfires themselves.

The researchers found that in B.C. in 2017 “wildfires emitted approximately 190 million tonnes of carbon into the environment, six times the total from all other sources.”

This number was almost triple B.C.’s annual carbon footprint.

Werner Kurz, a senior research scientist at Natural Resources Canada, estimates that wildfires in B.C. emit an average of 150 to 170 tonnes of greenhouse gases per hectare, though the number varies by forest type and burn intensity. (For comparison, a 2016 study found that the average house in Vancouver emitted 7.2 tonnes annually.)

“The key is it’s a very large number,” Kurz said. “The gases that are emitted by fires — carbon dioxide, methane, nitrous oxide — all are greenhouse gases with various potencies that contribute to global warming.”

It’s not just the emissions from the fire itself that can impact climate change. An intense wildfire also kills trees that would have removed carbon dioxide from the atmosphere.

“Years after the fire, the removal of carbon dioxide from the atmosphere will be slower than it would have been normally,” said Kurz.

Not only do wildfires emit greenhouse gases, they also reduce the ability of trees to absorb carbon from the atmosphere in the first place.

Kurz suggested that rehabilitating forests by planting trees can help reverse the emissions that fires have caused. “Grown trees are active carbon sinks,” he said. “Every cubic metre of wood that you can grow on the ground is a tonne of carbon dioxide that has been removed from the atmosphere.”

July 2017 the Canadian Armed Forces were deployed to aid in the fight against B.C.’s wildfires, viewed here over Kamloops. Photo: MCpl Gabrielle DesRochers, Canadian Forces Combat Camera

How do we adapt?

Adaptation to a new climate-fuelled fire season will be complex.

Fire ecologists across the country advocate for prescribed burns, whereby fires are ignited intentionally — when conditions are favourable — to burn off the excess fuel in the forest, and to create the natural barriers that burned areas create on a landscape.

Also important is not putting out each and every spark.

“It’s actually good to let some wildfires burn,” Daniels said. “In the short term, that’s a cost. There’s no doubt about that: it puts carbon into the atmosphere.”

But letting fires burn may diminish the possibility of catastrophic out-of-control fires in the future, by reducing the amount of fuel built up in the forest.

Wildfire has long been known to be a natural process that can have regenerative effects for forest ecosystems, and what’s referred to as a “natural fire cycle” is necessary in many landscapes.

But North Americans have long prioritized protecting timber, industry and homes over including important low-intensity wildfires on the landscape, and a century of forestry-management practises that favoured putting out wildfires as soon as they started (known as fire suppression) has also contributed to increasingly devastating megafires.

“With hindsight we know that was the wrong thing to do,” Gray said. But, he said, added to the concern is the fact that the whole cycle is fuelled by climate change.

“If we just had poor forest management practices, we could undo that. But the fact that we’ve got climate change on top of it, that’s just made it that much worse.”

Flannigan traces the issue back to human activity. “The root of the problem is we’ve got to stop burning fossil fuels,” he said.

“Even if we stop producing greenhouse gases today, we will continue to warm for the next 50 to 100 years, because of the lag in our climate system. We are going to continue to warm, so the time to act is now.”

Sharon is an Alberta-based writer and reporter. Her essays, interviews and long-form nonfiction have been published by The Walrus, Harper’s,…

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