Wildfire Forecast: More Devastating Seasons to Come for U.S.

"With this continued trend of warming, we are going to see more big fires."

The Science study concludes that climate change has lengthened the average wildfire season by 78 days and the average duration of large fires from 7.5 days to 37.1 days.

Enlarge Photo

Printer Friendly

Email to a Friend

What's This?

The Rocky Mountains are experiencing most of the climate-influenced large wildfires in forests, Swetnam adds.

Higher temperatures are arriving earlier in the spring, causing earlier snowmelts, which give grasses and trees longer to dry out and create fuel for summer lightning strikes, he explains.

Likewise, research published in the journal Conservation Biology concludes that the West should brace for even heavier wildfire seasons in the future. According to Donald McKenzie of the U.S. Forest Service's Pacific Wildland Fire Sciences Laboratory, the area burned by wildfires in some western states could double by 2100 if summer temperatures climb by 1.6 degrees Fahrenheit (0.9 degree Celsius).

Wildfires Always Unpredictable

Swetnam notes that although wildfires may continue to trend upward, there will likely be tremendous variability from year to year.

And even if the perfect conditions for wildfires exist, the fires may not necessarily come.

Both Arizona and New Mexico seemed ripe for major wildfires this year after an exceptionally dry winter that brought little snowpack to the mountains.

(Read related story: "Drought Causing Record Forest Destruction in U.S. Southwest" [December 2005].)

But those states were spared when record-breaking monsoons brought heavy summer rains instead of the fierce fires officials had expected.

Now fire officials in those states have a new worry: Summer rain might bring more grass that will become fodder for fire in the years to come.

As U.S. Park Service meteorologist Rich Naden noted in a National Geographic News article in April 2006, one lucky season doesn't change the long-term fire outlook in the Southwest.

"It's just a matter of time here," he said.

That sentiment is being echoed all over the West, where state, federal, and local governments have stepped up prescribed burns and strategic forest thinning to reduce potential fire fuel in critical regions.

Some communities in the Rockies are spraying forests where bark beetle infestations are killing trees in huge numbers and creating vast swaths of dead wood, said Jim Maxwell, spokesperson for the U.S. Forest Service.

"It's like trying to stop a hurricane," Maxwell said. "But everywhere, federal, state, and local officials are getting their heads and their money together to identify what they can protect."

An Upside and a Downside

Wildfires also provide certain benefits, Maxwell notes.

He observes that some forests that have been badly damaged by recent fires appear to be regenerating and may be healthier than they were before.

The University of Arizona's Swetnam agrees. "Fire can be a good thing because it does restoration work," he said. "But where you get high-severity fire in big patches where it hasn't happened before, entire habitats can be wiped out."

Fires can have different effects in different kinds of forests, he explains. Some species, like lodgepole pine, require extreme heat to release their seeds and therefore need fire in order to regenerate.

But other species, like ponderosa pine, are accustomed only to low-severity fire and may not grow back after an intense blaze.

McKenzie, of the U.S. Forest Service, suggests in his study that extensive habitat loss caused by large wildfires may reduce populations of some threatened species below healthy levels, making them more vulnerable to other ongoing threats.

Two years ago, for instance, the forest atop Mount Graham near Safford, Arizona, caught fire and nearly wiped out habitat containing 18 species found nowhere else in the world.

Swetnam points out that lodgepole-pine and spruce-fir forests of the Northern Rockies, where large fires occur only once every 100 to 300 years, may prove vulnerable to a revved-up fire cycle.

"[The forests] are very likely to change to something else as they burn more often," he said.

Free Email News Updates
Best Online Newsletter, 2006 Codie Awards
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).

<< Back to Page 1 Page 2 of 2