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Scientists See More Risk of Wildfires with Forest Changes

September 2, 2009 at 12:00 AM EDT
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Scientists are already witnessing climate change increase the threat of wildfires, as warmer temperatures drive more beetles to the forest, where they in turn kill trees and make the woods more susceptible to catching ablaze. Heidi Cullen of Climate Central reports.


JIM LEHRER: Now a second story about wildfires in the west. It’s about warming trends.

The reporter is Heidi Cullen, a climatologist and correspondent for Climate Central, a nonpartisan research group of journalists and scientists.

HEIDI CULLEN: This entire forest east of the Cascade Mountains has been put at risk by tiny pine beetles eating their way into the tissue of trees.

DR. SUSAN PRICHARD, forest ecologist, University of Washington: I find it amazing that such a small, nondescript little beetle can wreak such havoc on forest systems.

HEIDI CULLEN: Susan Prichard studies beetles as a forest ecologist at University of Washington.

DR. SUSAN PRICHARD: Each one of these yellow sap concentrations is an actual site where a mountain pine beetle has bored into the bark of the lodgepole pine. And then it will lay eggs and its larvae will actually feed on the cambial tissue, the living tissue of the tree.

So, here, each one of these centers is an example of the tree trying to pitch out the beetle. The actual sap of the tree has resins that are toxic to the beetles, and then, also, they physically push the beetle out of the tree.

HEIDI CULLEN: Wow. So, this tree is literally just fighting for its life.

DR. SUSAN PRICHARD: It is fighting for its life.

HEIDI CULLEN: Beetles thrive in warm weather. Milder winters, earlier springs, and longer summers mean more beetles.

DR. SUSAN PRICHARD: So there is a climate link with mountain pine beetle, for sure. And what we’re noticing in Washington State, even today, that, in the last 20 years, with warmer climate, warmer documented climate, there has been an increased incidence of mountain pine beetles.

HEIDI CULLEN: Prichard and other scientists say, if the beetles kill enough trees, eventually, more and more of the forest is vulnerable to intense wildfires.

DR. SUSAN PRICHARD: And, in the late 1990s, a predictable event occurred. Mountain pine beetle started to have a large outbreak. And, after the outbreak occurred, over about 10 years, there were accumulations of both dead spruce from spruce beetle, and dead lodgepole pine from mountain pine beetle that were susceptible to a big fire event.

Residents brace for more fires

HEIDI CULLEN: Prichard believes this outbreak set the stage for what happened three years ago, when the so-called Tripod fire swept through the Okanogan-Wenatchee Forest.

In 2006, the Tripod Complex fire, ignited by a lightning strike, burned some 180,000 acres, costing Washington State tens of millions of dollars. Local residents are bracing themselves for more fires like this one.

WOMAN: With the Tripod fire, for us, it was just so scary to think for that to repeat again. We had ash falling from the sky. It was landing on the car. You had to brush your car off. Walking through town, the visibility was probably 20, 25 feet.

Here we are in Winthrop.

HEIDI CULLEN: Rita Kenny owns a mountain sports store in the quaint Washington town of Winthrop. Her worry, more wildfires will drive away the bikers, backpackers, and skiers.

WOMAN: It certainly has a huge impact on business.

I think the biggest concern for us is that they're catastrophic fires, meaning that, when they start, they're going to go all summer long. They're going to encompass large areas. And the fires do burn so hot that the trails may not open for a couple years. So, it limits our recreation. And it's just unsafe.

PETER JAMES GOLDMARK, commissioner of public lands, Washington State: When I see a fire like that, it's a very painful experience, and you want to -- you want to put it out.

HEIDI CULLEN: Peter Goldmark manages all of Washington State's public lands. His concern, the long-term consequences of fires.

PETER JAMES GOLDMARK: It's destructive to the habit. It's a huge health impact on the residences all around. And it's scarring that landscape for really a century on the east side of the mountains, where precipitation is very low, and where recovery is very painful. It's very destructive.

HEIDI CULLEN: Fires like Tripod erupt during dry, hot months, a more and more common weather pattern for Washington State. Average spring temperatures have risen nearly three degrees since 1950. Natural variability makes some years cooler or hotter, but records show an overall warming trend. Following a cool spring, this July was among the hottest, and unusually low rainfall has left much of the state in a drought.

MAN: This part of eastern Washington, where my ranch is and where the Tripod fire was over three years ago, it's been historically dry here, and has been on the nation's wildfire map for being one of the areas most endangered.

HEIDI CULLEN: In fact, more than 800 wildfires ignited in Washington, well above the yearly average, among them, the more than 10,000-acre Oden Road fire in Okanogan-Wenatchee Forest in late August.

Since the late 80s, far more land has burned compared to the previous two decades, a pattern seen across the West. But back in Winthrop, not everyone believes warmer temperatures are causing the spike in fires.

Decline in the timber business

DOUG MOHRE, resident, Winthrop: After living here for 16 years, one of the things that I have noticed is the fires in the Methow Valley are basically like rain in Seattle.

You guys need help?

HEIDI CULLEN: Doug Mohre owns Sherry's Sweet Shop near Winthrop's one and only stop sign. For him, Forest Service practices are causing fires to get bigger.

DOUG MOHRE: The Forest Service no longer fights fires. They manage the fires. And once a fire gets to a certain size, they're more interested in controlling where the fire goes and where it burns, as opposed to putting it out.

HEIDI CULLEN: Roger Townsend, a disabled logger who lives in the nearby town of Twisp, blames more fires on a decline in the timber business.

ROGER TOWNSEND, resident, Twisp, Washington: The Sierra Club and the environmentalists, they think they're protecting the forest. But, by protecting it, keeping the loggers out, letting the disease and the bugs go rampant, they have done more damage than they have done good.

I consider myself a conservationist, but you have to use common sense. And it's a crop. You have got to take care of it. If you don't take care of it, nature is going to, and catastrophic wildfires are a result.

HEIDI CULLEN: But scientist James Agee says research shows there is a link between climate change and the spike in wildfires. He is an emeritus professor of forest resources at the University of Washington.

JAMES AGEE: We know that under, either warmer or drier conditions, that both live vegetation and dead vegetation -- that is, live and dead fuels -- become drier.

HEIDI CULLEN: The timing of mountain snowmelt is crucial, explains Agee. When the snow melts in early spring, arriving one to three weeks earlier, the fire season lengthens, giving forest vegetation longer to dry out. In fact, records show years with early snowmelt have far more wildfire than years where the snowmelt is late.

JAMES AGEE: If you think about the opportunity, let's say, for a lightning strike to hit drying fuel, in these drier conditions, we can get up to maybe 20 to 30 percent more fires occurring on that landscape.

Part of this is just kind of natural annual variability. But what we're anticipating is that that is going to be shifting towards a pretty consistent earlier snowmelt and a pretty consistent longer fire season, and, because of that, much more area burned, and much more severely burned area.

Need for better forest management

HEIDI CULLEN: Clearing away dry vegetation -- that is, potential fuel -- is one strategy to tamp back fires.

BECKI HEATH, U.S. Forest Service: This stuff is adapted to burn.

HEIDI CULLEN: It's part of Becki Heath's mission for the U.S. Forest Service and the Okanogan-Wenatchee National Forest.

BECKI HEATH: The dry forest strategy takes a look at about two million acres of our forest that we consider to be in a dry vegetative type, like this ponderosa pine, where the vegetation has been accustomed to frequent fire and where it's necessary for to us thin, remove the smaller trees that are competing with the large, healthy trees, and underburn -- again, to claim the forest floor to provide a more resilient situation for the trees to grow in.

HEIDI CULLEN: Lands Commissioner Goldmark says better forest management can have economic benefits and also release greenhouse gas emissions.

PETER JAMES GOLDMARK: I took a new initiative to the legislature and asked for their concurrence and their agreement on my biomass initiative, which is basically an effort to convert woody biomass -- and that's either slash piles from logging or material that's in forests that is dead or dying as a result of beetle kill or drought -- and remove that material out, and turn it into fuel.

HEIDI CULLEN: It will take far longer than one fire season to know for sure if the moves to cope with warming, beetles, and wildfires will make a difference.

Meanwhile, the recent upsurge in fires has altered the forests and the lifestyles of the people who enjoy them most.

JIM LEHRER: On our Web site,, there's more about how warming trends are affecting the severity of wildfires. There's also a link to Climate Central's Web site.