How Smokey Bear creates forest fires

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.

Read (or listen to) the rest of the story at NPR's website

Via Finn Ryan

Image: Forest Fire, a Creative Commons Attribution (2.0) image from wandrus's photostream



  1. Tell me about it. I work on a telescope on top of a mountain that’s so tightly regulated that it has a thick layer of fuel on the ground, and the trees are quite close together, and many of the trees are dead due to beetles, and they can’t cut them down due to regulations.

    It’s insane. The last fire burned a large part of the canopy completely away. The next will do the same, as the only thinning allowed seems to be in the vicinity of some cabins.

    1. Scary stuff, but where is this?  Over ten years ago in Yosemite, I heard a Ranger talking about how, lessons learned, they had already implemented the policy of allowing many fires to burn, then burn out by themselves.

      This in a park under the jurisdiction of the National Park Service, so it SHOULD be national policy, also in national forests.  State parks and forests, I dunno, but a discrepancy would be insane as late in the game as 2012.

  2. My grandfather retired after 50 years in the forest service, and would always “preach” to me about how all the kids these days are doing it wrong, and if they don’t let more stuff burn they end up with bigger fires than they can deal with. I’ve always wondered how his experience and knowledge don’t seem to get passed down to the people working on forest policies today.

    1. I thought that this was common knowledge after the Yellowstone Fires of 1988.  It was front page news for weeks.

  3. If we keep up the fire prevention tactic, thinning the underbrush has to be a tandem goal. It’s just as much a preventative action as not throwing cig butts into a ditch. 

  4. The story feels a bit out of date.. “zero tolerance” was certainly the policy towards fire for much of the forest service’s history, but that attitude has been changing the last several years as science has begun documenting the mistake it was. 

    One of the brochures I received on visiting a national park this summer even admits to this, and mentions that controlled burns are being employed to help preserve the “authenticity” of the environment. 

    I think the problem is it’s not a quick fix. They can’t just light a match and torch a few million acres to get things back on track. Budget and manpower concerns limit how quickly change can be implemented and there’s probably going to be several more massive fires before equilibrium can be re-established.

  5. Massive dosages of Fire Retardant chemicals may be not the sensible thing, but something eggheaded bureaucrats  might think is ‘technologically wise and fiscal. Drawing border lines of division for containment.

    Hopefully they don’t use chemicals.

  6. Yep, xzzy.  When I was living in California 20 yrs ago, we’d talk about this as we walked past piles of “slash” (flammable debris–dead branches and pine needles).  When I was 15, the first set of shasta fires (by forks of salmon and yreka) almost burned my mom out of her home.  I think that was also the year of the oakland fires– give or take.

  7. The other thing people need to adjust their expectations on is how many trees they expect to see on the side of a hill.  It’s pretty clear that in the old days the tree populations were kept in check by regular forest fires (really just grassland fires) to just a handful per acre.  If you want to return to that people will need to get used to the idea of seeing the mountainside bare again.

  8. My town, Butte, Montana, just lost a third of its water supply because a watershed (it hasn’t even burned yet) has created turbidity problems in the reservoir from routine runoff. Over the past decade I’ve watched the “red-and-dead” stain grow over the East Ridge (the Continental Divide) as the lodgepole pines die from beetle kill. It’s about 75 percent dead now.

  9. Well, about 15 years ago I participated in a control burn in Florida, but I don’t remember if it was in a state or national park.  Either way, park rangers have known about the need for fire for a long time.  I suspect it’s politics and not science that have kept control burns from being more widely used.

  10. But why don’t they cut the bush? That’s what we do in Southern France: large forest roads for the fire trucks and forest workers, removal of thick bush every few years (under not too dry season), observation towers on the top of the hills, water tanks spread in the forest, and circling planes.
    It’s not perfect, but it’s a best effort.

  11. In Australia it’s common practice for the state-based government conservation department to perform controlled burns every winter for exactly this reason.

  12. I just can’t stop seeing a wrathful Mark Twain, come back to chastise us  for our continuing folly, in the smoke cloud. Kind of a 3/4 right profile view, with hair and mustache billowing crazily. Maybe I need some medication.

  13. Do what us Australians do and routinely “burn off” high risk areas under the right weather conditions with controlled professional burning and fire fighters on standby.

  14. The Smoky Bear theory makes sense, as far as it goes. However the Russians ,  who clearly  never heard of Smoky the Bear .  Seem to have their hands full as well :
    Record temperatures and forest fires in RussiaBy Clara Weiss 
    15 August 2012Broad swathes of forest and dried-up bog land have been burning fiercely in large parts of Siberia since the beginning of June. The fires are raging out of control due to the region’s decrepit infrastructure. The fires were caused by the hottest summer in Siberia since the beginning of weather records 170 years ago. Temperatures have averaged around 34 degrees Celsius (93 degrees Fahrenheit) for weeks and are expected to remain high in the coming period. Tom Swetnam, Director of the Laboratory of Tree-Ring Research at the University of Arizona in Tucson ………..”“We’re trying to understand fire, climate change and carbon emissions out of Siberia because of the huge carbon pool contained there in the soil, permafrost, bogs and forests,” says Swetnam, a sturdy middle-aged man with an outdoorsy white beard. “This giant pool of carbon is beginning to burn in a massive way—the amount of area burning in Siberia is startling.”

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