From The Colorado Springs Gazette (Evan Wyloge):
Over the past two decades, fire seasons in Colorado have consistently grown larger and more destructive. The three largest wildfires in tracked history ignited within 10 weeks of one another this year, putting the year’s total wildfire-burned acreage above the past six years combined.
It’s a trend caused by several factors, experts and researchers say, and it’s likely to continue.
large fires that characterized this year, said Camille Stevens-Rumann, a Colorado State University professor whose research focuses on fire ecology.
“If you think about other areas like California, or even other Rocky Mountain states, like Montana or Idaho,” she said, “they’ve had huge fires. We’ve not seen those. We had Hayman in 2002, then bad years in 2010 and 2011, but we haven’t had to face this reality until this year.”
Hotter, drier seasons, along with some misguided forest management practices, are to blame, she and other experts agree.
Fires in Colorado are a natural event, they stressed. The lodgepole pine is cited as an example of how the ecology has evolved to coexist with regular fires. The tree’s pine cone opens and releases the seeds when it raises to a certain temperature. And the natural cycle is for the adult lodgepole pines to be burned…
Higher temperatures — average global temperatures have risen about 1 degree Celsius since the middle of the 20th century — mean the mountain snowpack doesn’t last as long, Hurteau said. The same higher temperatures that shorten the winter then, in the summer, sap moisture from the ecosystem, priming Colorado’s forest vegetation for a fire.
Two key metrics quantify for researchers how much the higher temperatures cause the more rapid drying of the environment.
“Vapor pressure deficit and climatic water deficit: How much moisture does the atmosphere want to pull out of the soil, versus how much there is,” Stevens-Rumann said. “As temperatures increase, there’s more demand in those two metrics.”
The natural process plays out every summer, but with snowpack disappearing earlier in the year and not arriving until later, it happens more intensely and for a longer duration…
Bark beetle is another factor that stokes Colorado’s wildfires. If a patch of trees becomes infested, after time, the trees die, leaving dead, drying timber that’s primed to ignite because of the drying pattern, the experts said. And while pine needles, twigs, loose foliage or leaves on the forest floor can burn quickly without burning larger trees, standing dead trees burn hotter for longer, further contributing to more intense fires…
Forest management practices have contributed to the problem as well. The doctrine of extinguishing forest fires as quickly as possible, without regard to the natural cycle of burning and regeneration for forests, has led to more fire-prone wildland…
He said there are now efforts to bring a better approach to forest management, which lets some of the fuel burn, to better match the natural cycle.