By now, many of you are probably aware that human behavior is one of the key factors behind some of the massive forest fires we've seen in recent years. The basic story goes like this: Under a natural cycle, periodic small fires sweep through forests, burning through small trees and dry brush. But if you prevent those fires from happening—as humans have done for around a century at this point—all that highly flammable stuff builds up. In the end, you're left with a giant tinderbox of a forest. The next time a fire does happen there, it's almost guaranteed to be much, much bigger and more destructive than the natural fires that forest is adapted to.
NPR has a very nice story about the science and history behind this problem, which forest fire experts call "The Smokey Bear Effect", after the cartoon Ursus the U.S. Forest Service has long used as part of its fire prevention campaign.
Its ill-advised fire prevention campaign.
And it was the experts who approved the all-out ban on fires in the Southwest. They got it wrong. That's the view of fire historian Stephen Pyne.
"The irony here is that the argument for setting these areas aside as national forests and parks was, to a large extent, to protect them from fire," Pyne says. "Instead, over time they became the major habitat for free-burning fire."
So instead of a few dozen trees per acre, the Southwestern mountains of New Mexico, Arizona, Colorado and Utah are now choked with trees of all sizes, and grass and shrubs. Essentially, it's fuel.
Over the past several years, even as fewer fires have struck the Southwest, they've burned more land. The U.S. Forest Service now spends about half its budget on firefighting.
It's worth noting that this is also a great example of why it's difficult to attribute specific events to global climate change. Increasingly hot, dry summers have certainly been a factor in creating the forest fires we've seen over the last few years. The last decade has been the hottest on record, and that has consequences. But it's not the only thing going on here. Climate change doesn't happen in a vacuum. Its effects interact with the effects of other decisions we make (and other natural events that happen to be taking place). So it's not enough to say what climate change will do. In order to make accurate predictions of risk, we have to think about the bigger picture and how climate change fits into it.
Via Finn Ryan