Experts explain link between wildfires and climate change

This year's wildfire season in Canada has been wild.

So far, more than 2,600 fires have consumed about 5.9 million hectares of forest across the country, according to the Canadian Interagency Forest Fire Centre. This represents more than three times the amount of area that burned in the entirety of last year’s wildfire season — and there are still months of fires expected ahead.

The impacts have been wide-ranging — from tens of thousands of people being forced to flee their homes, to poor air quality in several communities, which affects the health and wellbeing of humans and wildlife.

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WHAT IS CAUSING THE FIRES?

The recipe for wildfires calls for three main ingredients, said Mike Flannigan, British Columbia Research Chair in predictive services, emergency management and fire science at Thompson Rivers University.

Those ingredients are vegetation that is flammable — also referred to as “fuel” — such as trees, leaves and shrubs, the source of fire ignition, which tends to be humans or lightning, as well as hot, dry and windy weather conditions that cause fires to spread, he said.

Roughly half of forest fires are caused by lightning and the other half are caused by humans, although Flannigan said the number of human caused fires has been dropping over time, in part due to education around fire prevention and recent fire activity.

However, while there has been a decrease in human-caused fires in recent years, the area burned by forest fires in Canada has doubled since the early 1970s.

“And this is because lightning fires have more than compensated for any decreases from fires (caused by humans) and have led to this doubling of area to burn,” Flannigan explained.

HOW DOES CLIMATE CHANGE AFFECT THE FREQUENCY, INTENSITY OF WILDFIRES?

Experts say the reason wildfires are so pronounced this year is because of our changing climate, which is creating the conditions for fires to break out more easily, more frequently and more intensely.

Flannigan said the amount of greenhouse gasses in our atmosphere, including carbon dioxide and methane, has increased due to human activity and it’s warming the planet at an alarming rate — human-induced warming reached approximately 1 C above pre-industrial levels in 2017, according to the Intergovernmental Panel on Climate Change.

With warmer temperatures comes longer fire seasons, he said, pointing to Alberta as an example, which started seeing wildfires as early as February this year, months earlier than usual.

As well, with warmer conditions, Flannigan said the ability of the atmosphere to suck moisture out of the flammable vegetation like dry grass and trees increases, and unless there is more precipitation to compensate for this, there will be drier vegetation, which will lead to higher intensity fires.

“The big scary part is we're warming, we're seeing longer fire seasons, we're seeing more conditions for lightning and we're seeing higher intensity fires that are challenging to impossible to extinguish through using firefighters or aerial attack, so it means more escapes, which means more problems,” he added.

Smoke from wildfires burning across both Ontario and Quebec blanket the skyline in Kingston, Ont., Tuesday, June 6, 2023. THE CANADIAN PRESS/Lars Hagberg

Ryan Ness, director of adaptation research at the Canadian Climate Institute, echoed those remarks.

“In addition to a warmer overall climate, which creates a greater risk for things to dry out and to ignite in the case of wildfires, we're also seeing drier weather and we're seeing more weather that creates lightning as a result of more energy in the atmosphere, which drives more wildfires as well,” he said.

Climate change enables pests like mountain pine beetles as well, which kill “huge swaths” of forests, to survive in parts of western Canada where they previously were not able to because “there’s not a deep enough winter freeze to kill them off,” Ness said.

“So that certain indirect effect of climate change is adding even more fuel to the fire, as it were, and these (effects) are all combining to create a bigger, longer, earlier wildfire season across the country with more fuel to burn,” he added.

WHAT DOES THE FUTURE HOLD FOR CANADA?

Canada is currently experiencing its worst wildfire season of the 21st century and matters are expected to get worse — the federal government has said the amount of forests burned by wildfire is projected to double by 2050.

If the country sees this projected increase in frequency and intensity of fires, Flannigan said “the forest will disappear in areas,” but the risk of fires won’t end there as the forest will be replaced by grasslands and shrubs, which will also burn each year.

“So this is the new reality. I don't like the term ‘normal’ because that sounds like a steady state — we're on trajectory,” he said.

“Every year is going to be a bad fire year. 2023 is obviously a bad fire year. 2024 might see cooler weather, but on average, in the future, we're gonna see more bad fire years and we're seeing more bad fire years now than we've seen in the past.”

Ness agreed.

“(Humans and lightning) continue to be the causes, but the difference now is that when those fires start, they get much bigger and out of control than they used to because of the impact of climate change, because of the drought, because of the disease in the forest, because of the drying out that's creating the conditions for unbelievably intense wildfires,” he said.

WHAT CAN BE DONE TO PREVENT OR MINIMIZE THE RISK OF WILDFIRES?

In order to prevent the presence and spread of wildfires, both Ness and Flannigan said a multi-pronged approach is required.

“We have to adapt, we have to deal with this new reality of wildfires and other climate extremes and make sure that we're resilient to it,” Ness said.

Flannigan said this approach could involve introducing fire bans and forest closures well before fires are expected to break out, making the FireSmart program mandatory for homeowners and communities to follow as opposed to voluntary, enhancing early warning and fire danger rating systems, as well as speeding up the allocation of firefighting resources when wildfires break out.

To address the root causes of climate change, he said humans need to stop using “coal, oil and gas as soon as possible” and shift to renewable energy sources in order to reduce greenhouse gas emissions. 

“Urgent action is needed now,” Flannigan said.