MONTREAL -- The prevalence of wildfires has become difficult to ignore these past few years.

In 2020 alone, devastating fires swept across California, Australia, the Amazon, Siberia and Indonesia, to name a few places. Just a few years earlier, major fires ripped through parts of Western Canada, destroying homes and costing millions in damage. British Columbia saw its worst fires on record in 2018, with 1.35 million hectares burned.

As summers grow drier and hotter, fires are spreading more quickly and frequently. According to one team of researchers from McGill University, this is especially true when it comes to a particular type of terrain: mountains.

Over the decades, forest fires have inched steadily uphill, making their way up mountains which, at one point, were too wet to burn. Mohammad Reza Alizadeh, a McGill PhD student, says mountain forests have become increasingly arid, making them the ideal kindling for raging wildfires.

"Because of the climate warming, we’re going to see hotter and drier weather in the future," he said.

Alizadeh is the lead author of a recent McGill study that analyzed records of major fires in the mountainous regions of the Western U.S. between 1984 and 2017. The study, published June 1, found that fires travelled in an upslope advancement of roughly 7.6 metres a year.

"It was supposed before that the fire goes up to [certain] treelines, let’s say, but after that it vanishes because of the presence of humidity," he said. "But now [we see] decreasing humidity."

According to the study, forest fires have been enabled in an additional 11 per cent of western forests because of these progressively arid conditions.


While high-elevation forest fires can have severe consequences for mountain wildlife and ecosystems, they can also have a significant impact on life down below.

"[High elevation forests] are really important in terms of natural and also human systems and resources," said Alizadeh.

As Alizadeh puts it, high mountains serve as "natural-order towers," providing substantial amounts of water to the people and wildlife downstream. Forest fires can impact the quality and quantity of these waters, and dramatically alter the amount of time it takes for them to reach the ground, with flooding being an increased risk.

These fires even have an impact on avalanches, says Alizadeh, as a mountain’s forest can serve as a protective barrier against them. Without this "anchor point," avalanches can travel faster and farther. 

Alizadeha says that unless we take the steps to reverse climate change, these problems will become more pronounced over time.

"This is an unprecedented rate [...] that we’ll see more and more in the future, unfortunately."