Counting Canada’s hidden tundra fires

In wildfire season, sometimes you can’t see the tundra for the trees.

Most Northwest Territories communities facing any kind of wildfire threat are the ones in the boreal forest. For obvious reasons, the forest gets all the attention. That’s where the fuel and danger is.

As a result, nobody has really been counting the tundra fires that occasionally appear north of the treeline.

But those fires may be evolving, and that may have consequences that warrant our attention.

Tundra fires burn across stretches of barren grassland. Nunavut had a brush with a tundra fire last year when one was seen near Bathurst Inlet, but they are mostly quite small and far from any community.

As a result, recording them is tricky. If a fire rolls across the tundra and nobody sees it, who’s to say it ever happened?

Matthew Hethcoat and his colleagues are trying to answer that.

Hethcoat and colleagues at Natural Resources Canada’s Northern Forestry Centre began by studying satellite images from 1986 to 2022.

They trained software to know the difference between burned and unburned pixels of those images, then asked the software to find potential fires that nobody noticed over those decades. After that, humans reviewed the software’s suggestions to make sure there were no false positives.

The result? Before this work, there were around 60 recorded tundra fires north of Canada’s treeline between 1986 and 2022. The team found 209 new ones that hadn’t previously been noticed.

In the grand scheme of things, over more than 30 years, that’s not many – about six a year that had gone unrecorded.

“There were no blockbuster fires, nothing crazy that we had somehow missed over these decades,” said Hethcoat, “but a bunch of smaller fires that didn’t show up the way we’ve traditionally been looking to find them.”

‘Understanding what normal looks like’

NWT wildfire specialist Matthew Coyle says the research is important, even if it didn’t find mystery megafires burning in the wilderness.

Coyle’s job as a geomatics analyst is to make sense of aerial photography and satellite imagery, and figure out how to use that kind of information to make the territory better at managing fires and protecting communities.

He wasn’t involved in the research, but says it has made a “significant improvement” to what the NWT knows about tundra fires, a type of fire that have consequences as the climate changes.

“There’s very much a possibility that tundra fires will be a concern in the future, just given the sheer amount of carbon and methane that’s stored in peat land,” he continued.

“If we start finding we’re burning tundra at a rate that is far exceeding what it has in the past, that may have some pretty serious implications in terms of speeding up climate change.”

It’ll be hard to even know that’s happening, Coyle said, if we don’t know how tundra fires are behaving now and how often we’re getting them.

“We really don’t have good statistics on it. To be able to make informed decisions, we really need to know more about them. This research is establishing that baseline of data,” he said.

“To be able to properly gauge how things are changing, we need to first understand what normal looks like.”

Hethcoat and his colleagues are sure there are more tundra fires to be found that their technique didn’t pick up. Their first attempt, published in the journal Remote Sensing this month, is just the start, he said.

“We want to start to have a real, careful accounting of the fires that exist in Canada, so we can start to understand any potential changes that might be happening,” said Hethcoat.

“We’re at this tipping point where the amount of data – and the resolution and quality of the data – are going to give us a lot of information about our planet that maybe we didn’t understand before.

“As much as there is a lot to be concerned about the future, or scared or unsure, we have access to information and tools in a way that we just haven’t had before. It’s a really exciting time to be able to address some of the problems and the questions that are pressing in society.”