With hundreds of fires scorching northern Ontario, and Alberta and Northwest Territories battling bigger blazes than usual, this is potentially shaping up as one of the nation's most destructive wildfire years.
Forest fires have already left an indelible imprint in 2011. Flames razed or heavily damaged nearly 500 homes and businesses in the northern Alberta town of Slave Lake in May, while the threat of destruction has forced more than 3,000 people from their isolated northwestern Ontario communities.
Ontario is warning new fires are expected to start daily as dry conditions persist throughout the province. Across the country, more land has burned this year than during the same stretch in 2010, which was the eighth-worst wildfire season since 1970. More forests have already burned this year than in all of 2009 or in each of the four years before that. Blazes have blackened 2.4 million hectares, almost half the size of Nova Scotia, though the number of fires is down so far.
While it's difficult to predict how the rest of the summer will unfold, many experts have cautioned that large wildfires could become more common in Canada as the climate warms, which would mean increased lightning strikes and potentially drier forests. Indeed, a new study of wildfires in the northern Rocky Mountains of the United States is the latest research to signal a warning for North America's forests.
Researchers with the study, which will be published online this week in the Proceedings of the National Academy of Sciences, collected climate information from 1972 to 1999 and examined how it related to the frequency of large fires in the Rockies stretching from the Canadian border to the Teton mountain range in Wyoming. Using the statistical pattern created, researchers projected how climate change would affect fires in the region through this century.
What they found surprised them, said co-author Anthony Westerling, an environmental engineering and geography professor at the University of California, Merced. They'd expected fires would increase with higher temperatures, but they weren't prepared for the speed and scale of the projected changes.
Big fires in the greater Yellowstone ecosystem were predicted to become an annual event by 2050, whereas in the recent past, it was very common for no fires to break out. The study showed that by 2075, the frequency of wildfires could reach unprecedented levels, leaving forests with little time to adapt.
If this occurs, the very nature of mountain life would likely change profoundly. The mix of tree species could change, with some forests failing to regenerate after repeated fires. Shrubs and grass could replace vast tracts of dense forests, affecting wildlife and water resources.
"Some species will be winners and some species will be losers," Prof. Westerling said, adding a note of optimism. "The ecosystem has proved to be quite resilient in the past and it will probably surprise us with its resilience in the future."
Prof. Westerling expects the study's projections would translate north of the border, to Rocky Mountains in British Columbia and Alberta. One uncertainty in the prognosis is precipitation, which is trickier to forecast.
Fires are vital to maintaining healthy forests: They help reduce pest and disease infestations. But if their size and frequency increase as expected, the threat to people and businesses could, too, escalate.
"Most of the signals are that many areas of the globe are seeing more fires, more area burned, and longer fire seasons," said Mike Flannigan, a senior research scientist with the Canadian Forest Service and professor at the University of Alberta.
Canada is no different. Prof. Flannigan has studied the relationship between fire and climate change. He noted studies have suggested fire activity could double in Canada by the end of the century.
With the boreal forest alone covering one-third of the country, Canada has been seen as a global leader in wildfire management. While there's room for improvement, Prof. Flannigan contends provinces are reaching the point of diminishing returns and should "start looking at fire in a different way." Increasingly, the key dilemma facing officials is: Which fires to fight and which to let burn?
The Canadian Forest Fire Danger Rating System is designed to help officials assess the risks, but they system needs updating. Work on developing an enhanced danger-rating system has begun, in part because of the anticipated rise in wildfires linked to climate change.