The wildfire raging in the Canadian province of Alberta is driving one of the largest evacuations in North America in recent memory, said Bill Stewart, co-director of the University of California's Center for Fire Research and Outreach at the University of California, Berkeley.
With few exceptions in the United States, an entire town hasn't been threatened on this scale for over 100 years, he said, noting rather that devastation has struck neighborhoods and smaller communities in California.
There is no stopping the advance of a fire such as the wind-driven flames in Alberta, which is spreading embers well beyond fire lines, Stewart said. He said the aggressive fire is also unusual for burning so early in the warm season and so far north.
"You could add five times the number of firefighters, but you can't get all the embers," he said. "There's no way to put out every ember flying over firefighters' heads."
The mass evacuation Alberta is reminiscent of a Colorado fire in 2012 that forced more than 32,000 people out of their homes ahead of a blaze that quickly spread from the mountains into Colorado Springs.
Then, as in Alberta, traffic jams snarled evacuation routes as masses of people tried to flee the fire zone at once. But the evacuation efforts in Colorado were largely successful — more than 500 houses burned in the fire, while two people who officials said were trying to leave were found dead in the rubble.
More than a million people in 2007 were ordered to evacuate from their homes in Southern California, amid the threat of 14 major wildfires, said California Department of Forestry and Fire Protection spokesman Daniel Berlant.
A wildfire forcing evacuations in Alberta is burning through a type of forest comprised of shorter conifers where destructive and fast-spreading crown fires tend to be more common than in forests found in the contiguous United States.
Fuels and fire analyst Robert Ziel of the Alaska Interagency Coordination Center says boreal forests found from about 50 to 65 degrees north latitude tend to have tougher growing conditions.
Black spruce, jack pine and lodgepole pine tend to be 40 feet (12 meters) or less in boreal forests that in some areas even grow atop permafrost.
In the continental U.S., some of the most destructive forest fires involving crown fires burned through lodgepole pine in Yellowstone National Park in 1988 and destroyed about 1,200 square miles (108 square kilometers).