Peatlands are one of the staples of the boreal forest that sweeps across Canada. The 185 billion tonnes of mossy wetlands across the country can act as firebreaks, literally dampening the flames as they move across the landscape.
But when dried, the peatlands are a tinderbox — and a new study says the latter is becoming more and more common as the climate warms.
"Fire risk is going to become greater," says researcher Mike Waddington of McMaster University.
"It'll burn more often, the area burned will increase, but most importantly is the severity of that burning."
The researchers combined field observations with models of wildfires under different conditions to see how fire behaved in wet and dry peatlands.
Peat fires are especially smoky. Waddington's paper cites a study that found the 2010 peatland fire near Moscow was responsible for more than 3,000 deaths from poor air quality.
They can also burrow underground and re-emerge days or even months after appearing to have been put out.
Peatlands can be dried in a number of ways. When managed for forestry or for peat harvesting, they are often drained; however, they are also drying on their own as a result of climate change.
Peat is actually a precursor to low-grade coal, and can itself be burned as fuel. But fighting fires on peatland, paradoxically, can add fire risk over time. When left unburned over time, peat wetlands lose their fire resistance.
"If we suppress fire and don't let these ecosystems burn, you will lose this super-moss, this moss that's quite fire resistant," says Waddington.
"These peatlands generally burn and generally recover fine. The key is that if you get these megafires, when either the peatland is drained or you get severe drying under climate change, where they become bigger issues."
'Something we consistently deal with'
The Northwest Territories government's Fire Operations department does not have special policies for dealing with peatland fires, says Rick Olsen, N.W.T.'s fire operations manager.
"It is something we consistently have to deal with, but it is dealt with no differently than we would any other kind of wildfire," he says. "Every fire gets assessed in part with the fuels and vegetation that affect it."
Peatlands can also become densely overgrown with black spruce, an especially dangerous tree for wildfires. Waddington says black spruce played a role in the recent devastating fires in Slave Lake and Fort McMurray.
"Black spruce does something known as spotting," he says.
"It can shoot embers up to two kilometres...causing spot fires well before the fire reaches the town limits."
As the fire took hold in and around Fort McMurray and the city was evacuated, many residents drove south along Highway 63, which was bounded on both sides by nightmarish scenes of burning peatland.
The cruel irony of burning peatland is that as the climate warms, it dries more bogs. Those bogs hold more carbon than the Amazon rainforest, and when they burn, they release that carbon, further accelerating their own drying.
There's a fix
But Waddington says the process is reversible.
"The good news from the research we've shown is we know how to mitigate this fire risk: restoring these peatlands," he says.
The team re-ran computer models to see what effect adding moisture and moss to the peatlands had, and the results were encouraging.
"In the case where the peatlands have been managed for forestry, we can thin the trees, and we can re-wet the ecosystem… The key is to get these critical keystone moss species growing on the surface again."