Richard A Lovett
It’s well known that wildfires devastate forests, incinerate wildlife, release appalling clouds of smoke, and threaten homes and communities. But some of these wildfires, particularly those in the Arctic and sub-Arctic, may be playing an increasing role in spurring climate change, simply because they release massive quantities of carbon dioxide into the atmosphere.
In many parts of the globe, burned lands regenerate quickly, pulling nearly as much carbon dioxide out of the atmosphere in their regrowth as was released by the flames. But far-northern wildlands, known as boreal forests, burn intensely, release tremendous amounts of carbon dioxide, and take decades to perhaps a century to regenerate. So says Brendan Rogers, an earth systems scientist at Woodwell Climate Research Centre, in Massachusetts, US.
These fires are also becoming increasingly severe, Rogers says. “The burned area has roughly doubled in Alaska and Canada in the last 50 years, and in climate models we see that it is mostly likely going to continue and potentially accelerate,” he says.
In a study published last week issue in Science Advances, Rogers and a team of economists and other ecosystem researchers took a deep dive into the problem. They found that at projected rates of conflagration in the next 30 years, boreal forests in Alaska and Canada alone are likely to pump enough carbon dioxide into the atmosphere to add up to about 3% of the global total scientists think the atmosphere can handle if we are to stave off the worst impacts of climate change.
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Three per cent isn’t a lot compared to fossil fuel emissions, but it is a significant and previously unrecognised amount that needs to be accounted for. And that figure is actually likely to be an underestimate, partly because it was limited to boreal forests in Alaska and Canada and didn’t include those in Eurasia, but also because wildfires don’t just emit carbon dioxide – they also emit methane, nitrous oxide, and gases that effect the ozone layer. “We didn’t account for that,” Rogers says.
The news isn’t all bleak, however. These emissions, Rogers says, can actually be reduced on a price-per-tonne-of-carbon-dioxide basis. Assessed on that measure, the reductions could be comparable to or better than what can be achieved by many other methods of carbon offsets or abatements, including most forms of alternative energy.
The solution is better fire management.
Currently, Rogers says, fire management in these forests is focused on protecting people, property and infrastructure. It’s not focused on reducing greenhouse gas emissions. But from data collected in Alaska, his team found that fire-management efforts in these forests not only save buildings and reduce smoke, but reduce carbon dioxide emissions at a rate of $US12.63 per tonne. Ramping up fire-management efforts in Alaska and elsewhere might therefore be a cost-effective way to do a lot to reduce the projected climate impact of boreal fires.
Above and beyond these considerations, boreal fires are dangerous and inherently destructive to ecosystems, tourism, and indigenous communities. Better managing them might be a win-win, both locally, and globally. “These wildfires are affecting a lot more people than just on the local level,” says Carly Phillips, an ecosystem ecologist currently at the University of Victoria, Canada. “The climate doesn’t care where it burns.”
In some parts of the world, intensified fire suppression would be counterproductive, promoting the build-up of flammable brush and small trees that, when eventually ignited, can turn small fires into monsters.
But not so for boreal forests, Rogers says, because they were never prone to small fires. When they ignite, everything burns – meaning that suppressing today’s fire won’t make tomorrow’s worse.
Meanwhile, Phillips notes that there is a stunning amount of carbon stored in these forests and the soils they protect: about two-thirds of the total in all of the world’s forests, combined.
“From a climate change perspective,” she says, “that can really raise the stakes. Without taking that into account, we are jeopardising our ability to meet our climate targets.”