Climate change was the driving force behind destructive 2017 B.C. wildfire season, study says

The record-breaking B.C. wildfires of 2017 may have burned as much as 11 times more land than they would have without the influence of human-caused climate change, according to new research.

The study, from scientists at the Pacific Climate Impacts Consortium at the University of Victoria and Environment and Climate Change Canada, suggests that climate change was the driving factor for the unusually hot conditions that led to the fires. The probability of abnormally high temperatures being caused by global warming was estimated at more than 95 per cent.

The lead author of the paper, published in the journal Earth's Future last month, is Megan Kirchmeier-Young, an atmospheric scientist with the federal government.

"We have demonstrated that human-induced climate change has significantly increased the likelihood of extreme high temperatures, of extreme wildfire risk of large areas burned, similar to what we saw in the 2017 wildfire season in B.C.," Kirchmeier-Young told CBC.

More than 1.2 million hectares of B.C. burned in 2017, and 65,000 people were forced out of their homes by wildfire. By almost every metric, it was the worst season on record — that is, until the summer of 2018, when more than 1.35 million hectares went up in flames.

Though researchers have long said that climate change is responsible for a trend toward longer and more destructive wildfire seasons, it's been more difficult to directly connect a single disastrous summer to global warming.

To make that link, the researchers used a technique called event attribution analysis.It's a method that compares how likely a certain natural disaster might be on a planet affected by human-caused climate change than it would be in a more untouched world.

Because most global warming has been seen since the 1970s, Kirchmeier-Young and her colleagues compared conditions from 1961-1970 to those from today and took into account the human activities that drive climate change, including greenhouse gas emissions and changes in land use.

Increased wildfire activity likely in the future

They found that the extreme fire risks of 2017 were made two to four times more likely because of anthropogenic climate change and the area burned was increased by a factor of seven to 11 times.

That doesn't bode well for the future.

"If we see the temperature trends continue, then increased temperatures in the future result in increased wildfire," Kirchmeier-Young said.

The researchers did not find evidence of how anthropogenic factors influenced rainfall — on top of being unusually hot, the summer of 2017 was also abnormally dry.  

They also point out that there are still uncertainties about how non-climatic factors contributed to the record-breaking fires. Poor forest management practices including a lack of controlled burning, for example, have also been blamed for some of the damage caused by wildfires in recent years.