The Northwest Territories’ devastating 2014 wildfire season is central to a new scientific paper which in part suggests efforts to control climate change could be undermined by growing ‘megafires’.

Hundreds of fires burned in the NWT that summer, leading the territorial government to spend more than $55 million – more than eight times its budget – trying to bring some of them under control.

In the two following summers, researchers went into more than 200 randomly located burn areas to learn more about what burned, why it burned, and how wildfires changed depending on local conditions.

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Scientists involved in the project say studying the vast complex of fires in this detail will improve our understanding of how wildfires contribute to climate change – and help governments do a better job of factoring wildfires into emissions estimates.

“The work we have done here uncovers which parts of the of the boreal landscape are most vulnerable to large carbon emissions,” said Dr Brendan Rogers, who contributed to the paper.

“[That] helps us scale field observations to the large areas ultimately needed for climate-smart fire management and national accounting.”

The paper, from a team of 10 researchers led by scientists at Northern Arizona University, was published in the journal Global Change Biology last month. The work was funded by the NASA Arctic-Boreal Vulnerability Experiment.

‘Positive feedback’

Of note, the study’s estimate of 2014’s total burn area in the NWT is somewhat smaller than earlier published estimates. Previously the burn area was reported to be as large as 3.5 million hectares; this study’s own estimate is around 2.85 million hectares. Researchers say this could be due to previous estimates inadvertently including many small lakes and small patches of unburned forest amid larger burn areas.

However, the overall message is clear.

“Globally, the boreal forest stores approximately 40 percent of terrestrial carbon and has historically been considered a carbon sink,” the paper reads.

“However, recent climate warming and drying has led to an intensification of large wildfires, particularly in the boreal forests of northwestern North America.

“Increased combustion associated with this changing fire regime could shift this region of the boreal forest from a carbon sink to a carbon source, which would act as a positive feedback to climate warming.”

In other words, if wildfires in areas like the NWT continue to grow in size, the boreal forest may start to accelerate climate change rather than help temper it.

‘Out the window’

Dr Rogers – who works at the Woods Hole Research Centre, a climate change think tank based in Massachusetts – thinks the impact of wildfires on climate change isn’t yet fully accounted for in models.

“You cannot think about using land to mitigate climate change without accounting for wildfires, and right now fires are not integrated into any climate mitigation plans,” he told the centre’s own website.

“Intensifying fire regimes in northern forests from climate warming represent a serious threat to climate mitigation goals,” he added.

“Our ultimate aim is to figure out if and how land management can keep an appreciable amount of these massive carbon stores in the forests, and out of the atmosphere.

“Nonetheless, management can only do so much; without a steep reduction in fossil fuel emissions, climate-fuelled wildfires will ultimately overwhelm forest management, and many of our land-based mitigation measures will go out the window.”