Living on Earth: Burning! A Longer US Fire Season May Be the New Normal
Scientists estimate that the fire season now lasts 75 days longer than it did 40 years ago. In 2012, there were fires in places researchers thought would never burn, including parts of Rocky Mountain National Park in Colorado. One expert on western forest fires is Jason Sibold. He teaches geography at Colorado State University and says he knows what's causing the change.
SIBOLD: There are definitely relationships between beetles and forest fires. We’ve had extensive beetle outbreaks across the Rockies, across most of the west in the last two decades. At first, there's just thought that, well, all this dead fuel...it must be more flammable. When I build a campfire or something, I use dead trees, right, I don't use live trees. But when we really start to study this, it just doesn’t hold true.
With wildfires, the mass of these live fuels is held up in the canopy, and these canopy trees even when they're alive, if they’re dry enough and it's hot enough, they become extremely flammable. The needles, the twigs, the really small stuff, becomes extremely flammable. And the beetles, in reality, once they kill a tree, all of those fine fuels are moving from the canopy, a place where they can be highly flammable, they're moving to the forest floor. They’re compacting, and they're not quite as flammable; they're holding their moisture longer. And we're left with that ball of that tree that’s just not as flammable as a really dry live tree. So beetles are not just a big factor in what we're seeing. What we're seeing is climate, climate, climate.
CURWOOD: So don’t blame the Spruce Bud Worm, don’t blame the Pine Bark Beetle, blame anthropogenic climate change.