A wildfire burns in northern Manitoba near near Flin Flon, as seen from a helicopter surveying the situation, May 14.David Lipnowski/The Canadian Press
An international report published Wednesday found that Canada’s 2023 wildfire season burned six times more area than usual and released nine times the usual amount of carbon, ranking it as one of the worst across the globe.
These wildfires, which raged from Nova Scotia to Vancouver Island, emitted almost a decade’s worth of carbon dioxide, compared to the average for the area, said the inaugural State of Wildfires report, published in the journal Earth System Science Data which included expert panels from continents across the globe.
“Whatever statistic you look at for Canada last year is absolutely striking,” said Dr. Matthew Jones, lead author of the report and research fellow at the Tyndall Center for Climate Change Research at the University of East Anglia in Britain. “If you look at the number of fires, the area burned, emissions, the size of the fires … pretty much every record was smashed.”
The report examined the drivers and emissions from wildfires across the globe, including outbreaks in Canada, West Amazonia and Greece. It found that wildfires globally emitted 8.6-billion metric tonnes of carbon dioxide, 16 per cent above the average. Overall the historic record for carbon dioxide emissions released by wildfires was not surpassed, however, this was only because the fire season in the African savannah was relatively calm.
The report shows that Canada’s wildfires are “upsetting the balance of things,” Mr. Jones said. Canada’s boreal forest is a significant carbon sequester that, when burned, releases carbon back into the atmosphere, which then exacerbates climate change and in turn increases the likelihood of future wildfires.
Boreal forests can also take decades to recover from a wildfire. Devastating wildfires therefore lead to a long-term deficit in carbon storage.
Carbon emissions from wildfires were calculated in two ways, said Francesca Di Giuseppe, another author of the report and senior scientist at the European Centre for Medium-Range Weather Forecasts. The first is via real-time satellite observation. The emissions can be calculated by watching the fire and estimating how much carbon is emitted from the type and scale of vegetation burning.
The second is through looking at the landscape after the fire and comparing it to photographs from before. The blackness of “burn scars” paints a picture for how much vegetation burned and therefore how much carbon was emitted. For example, if the fire is particularly extreme, it will also burn the soil, which is an important carbon sequester.
The study also examined the drivers of the wildfires. It found that dry conditions at the start of Canada’s summer, which parched vegetation, was a major factor leading to the wildfires. This dry weather was around three times more likely because of climate change.
However, it was harder to find the drivers toward the latter part of the season, said Joe McNorton, study author and scientist at the European Centre for Medium-Range Weather Forecasts. Part of the reason was the unprecedented nature of Canada’s 2023 wildfire season. The scientists used artificial intelligence, which is trained on historical observations, to better understand the wildfires. But there were no such extreme wildfires in the past, adding to the difficulty of the prediction.
For example, forest firefighting resources had not been required so extensively and for that length of time in the past. How they would respond to fires as the season continued was therefore hard to predict. Fire seasons of the past were also not preceded by such a long dry spell, which also would have changed the behaviour of the fire.
“The models have never really seen anything on that scale,” Mr. McNorton said, adding that the modelling will get better over time. “The more we have of these seasons, the more these seasons become normal and the more historical data we have.”
The study ran projections on the likelihood of future extreme wildfires under different climate scenarios. Should emissions continue on their current trajectory, by 2100, wildfire seasons like 2023 will be six to 11 times more likely in Canada. However, if emissions are cut to the targets laid out by the Paris Agreement (a reduction in global emissions to net zero by 2050), extreme wildfire seasons will be only two to three times more likely, which means over two-thirds of the increased risk this century can still be avoided.
Elsewhere in the world, the effects could be even more significant. Should emissions meet targets, there won’t be a significant increase in the likelihood of extreme fires in Southern Amazonia or the Mediterranean.
Mr. Jones is curious to see how these emissions will affect Canada’s national carbon budgets.
Canada, like all nations, does not currently include wildfire emissions in its annual update on GHGs. Canada’s yearly National Inventory Report focuses on human-caused emissions, not natural disturbances, such as wildfires.
This means that wildfire emissions are not reported to the intergovernmental panel on climate change or in reporting to other international agencies, said Lori Daniels, an associate professor at the University of British Columbia. Ms. Daniels was not involved in the State of Wildfires Report, but she also researches the multiple drivers and effects of Canada’s wildfires on ecosystems and communities.
In her research, Ms. Daniels has found that wildfire emissions can be two to three times larger than that emitted from industry and human activity, provided that the reporting from industry is accurate.