Smoke from the Deer Creek Fire in 2004 billows over Yukon–Charley Rivers National Preserve in east–central Alaska during the state’s worst fire season on record. Photo courtesy National Park Service.
If you have the sense that U.S. forests are going up in flames, you’re right. In 2006, wildfires burned 9.4 million acres across the country, a million more than burned in 2005. The increase was no big surprise—the numbers have been rising for years. Some people argue that the trend is a result of questionable management practices, primarily fire suppression, which, in some dry forests, has built up enormous quantities of flammable fuel waiting for a tossed cigarette or a lightning strike. But many scientists believe climate change is trumping “normal” fire scenarios and will multiply the effects of fire suppression many times over.
In a one–page memo prepared in November for Interior Secretary Dirk Kempthorne, top federal officials warned of future firefighting challenges. They listed the combined effects of the growing numbers of homes built in forests, high fuel loads, lagging forest thinning efforts, and an increasingly warmer and drier climate. The Oregonian, which obtained a copy of the memo, quoted the report as saying “current trends related to wildland fire management are leading toward ‘perfect storm’ conditions,” and added that the scenario will severely test the nation’s firefighting capacity. But the U.S. Forest Service, which has employed a host of unsuccessful firefighting plans in the past, has yet to develop a realistic and comprehensive coping strategy.
Current federal wildfire policy is guided by President Bush’s 2002 Healthy Forests Initiative and its companion, the Healthy Forests Restoration Act of 2003. The acts present fire suppression and excessive fuel loading as the primary causes of wildfires. On the Healthy Forests Initiative website, climate change is not mentioned as a factor in increased wildfires.
Recently retired Forest Service Chief Dale Bosworth agreed that climate change, coupled with decades of fire suppression, is resulting in more severe fires. “For years, we have been trying with mixed success to manage uncharacteristically severe wildfires and outbreaks of forest pests,” he said in a speech before the North American Forest Commission in November 2006. “Now, we are coming to see that climate change is part of the underlying problem—and a common thread.”
But when it comes to suggesting approaches that would meet the challenge of fighting hotter, larger and more frequent fires, Bosworth had little to say about the specifics of managing wildfires. His recommended solutions to climate change effects have included “managing fuels to maximize energy utilization while minimizing carbon emissions,” and building the carbon storage capacity of both public and private forests. The fire question remains unanswered.
This lack of leadership is apparent on other administration levels as well. Regarding climate change, “the recognition of the seriousness of the issue goes from the chief down to my level,” says Tom Harbour, the Forest Service’s director of Fire and Aviation Management, but he didn’t cite specific fire management practices linked to climate change.
In the absence of clear policy direction, Forest Service employees on the ground may not know how to begin coping with the looming fire challenge. “If I were a district ranger, I would probably be a little overwhelmed as to what I could do at the local level,” says Jim Furnish, former manager of Oregon’s Siuslaw National Forest and retired deputy chief of the Forest Service. Although climate change strikes Furnish “as a global crisis,” he says it is not fundamentally shaping the thinking of the agency.
“It would seem to argue for an urgency,” he says. But the Forest Service is “still addressing symptoms. They’ve got big Band–Aids.”
FIRE, BUGS AND HOMES
The two most profound change agents in forests are fire and insect invasions, which work more synergistically as temperatures rise.
The science strongly supports the connection between the increasing prevalence of forest fires and a warming world. In a study of wildfires over two seventeen–year periods between 1970 and 2003, a team led by environmental economist A.L. Westerling, of the University of California, Merced, showed that snowmelt came earlier and spring and summer temperatures were higher in the later period. That time frame also saw a seventy–eight–day extension in average fire season length—an increase of more than two months. These warming indicators corresponded with a fourfold increase in wildfire frequency and more than a sixfold increase in total area burned.
Science is also clear that climate change enhances insect incursions. The spruce budworm lays half again as many eggs at 25º C (77º F) as it does at 15º C (59º F). As temperatures rise, insects can enter regions formerly closed to them by cool temperatures, glaciers and mountain snowpack. Insect–stressed trees have lowered resistance to fire, and fire–weakened trees are more vulnerable to insects.
Long–standing agency policy has been to suppress fires whenever possible and regardless of cost. Although the Forest Service now acknowledges that fire suppression has been a mistake, it is not clear how current responses to fire will work in a scenario that includes rising temperatures. For example, prescribed burns can be effective in reducing fuel loads, but the risk of a runaway burn is often too high in a hotter, drier climate.
Thinning is not always the best alternative. It costs about $800 an acre, according to a 2000 Sacramento Bee article. And budget and personnel cuts on forests like the Wallowa–Whitman in northeastern Oregon, which now has less than a third of its 1990 staff, have so dramatically affected management that there are “more acres to treat, generally of much lower revenue–producing value, with far fewer staff to do it,” according to a recent report sponsored by several conservation groups.
In addition, different forests comprise radically different ecosystems and are managed for different objectives—timber harvest, habitat preservation and biodiversity among them. All of these may require varied responses to climate change and the types of wildfires it spawns.
Fire management in the national forests is also complicated by the fact that forests are increasingly viewed as vacation spots for human beings, both for recreational activities and for dwellings. Wildfires destroyed nearly 1,000 homes a year between 1985 and 1994. The Forest Service spent more than $1 billion annually from 2003 to 2006 protecting people and property from fire, according to a November 2006 audit report by the Department of Agriculture’s inspector general. The problem is not going away. More than 8 million new homes were built in wildland–urban interface zones between 1990 and 2000, and nearly two–fifths, or 50 million, of all homes in the United States are now within these zones, according to Firefighters United for Safety, Ethics, and Ecology.
JOINING FORCES
Some Forest Service researchers and managers are pooling their knowledge to incorporate adaptation to climate change into their research topics and practices. Dave Peterson, with the Pacific Northwest Research Station’s Pacific Wildland Fire Sciences Lab, wrote in 2004 that in upcoming decades “wildfire will burn 2–3 times more land area in most of the western United States than it does today.”
Peterson and Forest Service research ecologist Don McKenzie used statistical models to predict changes in wildfire area in response to increased temperature in the twenty–first century.
In a report due out this spring, they outline the effects climate change will have on western forests, including increased fires. “Wildfire is the most important natural ecological disturbance in western North America, and understanding the effects of climatic variability and change on fire regimes is essential,” they conclude.
A recent study by Tania Schoennagel of the University of Colorado–Boulder and colleagues showed that, although thinning can be an effective method for preventing catastrophic burns, it may not be an appropriate climate change response in every forest. The team found that fuel reduction in most Rocky Mountain subalpine forests consisting of mixed conifers such as Douglas–fir, Engelmann spruce and lodgepole pine would likely do nothing to minimize fire damage, whereas dry ponderosa pine forests at lower elevations would benefit from these measures. The authors warned against a “one size fits all” management approach to the diverse forest types in the Rocky Mountain region.
Another useful finding, Peterson says, is that genetic variety increases a forest’s resilience. In a timber–productive Douglas–fir area, for example, “we might plant a variety of genotypes instead of one type that’s supposed to be best for that zone,” he says. “Instead of putting all your eggs in one basket, just diversify a little.” Mixed tree species can discourage severe insect outbreaks. While insects can be flexible in their diet, says McKenzie, they tend to prefer one tree species, and if they don’t encounter a monoculture, they can’t go on a binge.
There is also a movement afoot to coordinate information from different agencies. The Forest Service, along with several other federal agencies, is preparing a chapter on strategies for adaptating to climate change that will be included in a report to the U.S. Climate Change Science Program.
Experts predict that 2007 may be the hottest year on record, in part because of the additive effect of an incipient El Niño. The “snowballing” of global warming may overwhelm traditional wildfire management strategies, and even new strategies may fail to prevent a severe environmental shift. But if forest practices don’t change at all, we risk seeing even more trees go up in smoke.