Canada — In the fight against climate change, forests play a critical role drawing more greenhouse gases out the atmosphere than they emit.
But when they burn, much of those stored gases are released back into the atmosphere.
So far, the fires in Fort McMurray have released the equivalent of roughly five per cent of Canadas annual greenhouse gas emissions from all other sectors, said Werner Kurz, a senior research scientist with the Canadian Forest Service in charge of Canadas National Forest Carbon Accounting System.
The average emissions from forest fires in the boreal plains, where the northern Alberta fires are occurring, are about 170 tonnes of carbon dioxide equivalents per hectare, Kurz said.
Multiply that by 239,390 hectares, the size of the Fort McMurray fire May 11, and the fire has already released about 41 megatonnes of CO2 equivalents in the form of carbon dioxide, methane, and nitrous oxide.
In 2014 Canadas total greenhouse gas emissions were 732 megatonnes, excluding emissions from wildfires and other land use, land-use changes, and forestry activities.
The fires in Fort McMurray have already covered about 10 per cent of the average territory burned by wildfires every year in Canada a significant feat for one fire so early in the season, said Bill de Groot, a research scientist at the Canadian Forest Services Great Lakes Forestry Centre.
On average wildfires, burn two million to 2.5 million hectares a year in Canada, he said.
So its a really large amount for the very start of the fire season and theres still a full fire season ahead of us, so it could potentially be a bad year if we dont get some rain, de Groot said.
But to really understand the climate impact of the fires you have to take a longer-term view de Groot said.
For 6,000 years boreal forests have operated on a cycle of growth, fire, and re-growth, said Merritt Turetsky, an ecosystem ecologist at the University of Guelph and a Canada Research Chair.
Basically, what we know is that black spruce proliferated into the boreal forests around that time and fire came with it, she said.