SEATTLE — Biologist David Peterson cringes when he hears the statement: “Climate change is causing wildfires to become larger, more frequent and more severe.”

While it’s true that in 2012, the warmest year since 1895, more of the Western U.S. burned than in any other year on record, “Many scientific statements become ‘fact’ for no better reason than they are repeated frequently at meetings,” he said during a recent seminar on climate change.

Many other factors come into play in forest fires, like increased fuel loads in unthinned stands and more trees dying from pest or disease pressure, he said.

He pointed to a chart showing how many acres of Western forests have burned annually since 1916. The broad trend over the decades mirrors another chart, this one tracking ocean surface temperatures in a cycle called Pacific Decadal Oscillation.

The pattern of warm-cool-warm cycle closely matches a pattern of peaks and valleys of forest acres burned.

“The data indicate we may be entering a cool (cycle),” he said.

As a research biologist with the U.S. Forest Service Pacific Northwest Research Station in Seattle, Peterson sees what that might look like. If global temperatures rise 1 degree Centigrade, projections say, the Western U.S. could see two to three times as much acreage burned.

Reese Lolley, who directs The Nature Conservancy’s Eastern Washington Forests Program, said fire will always be part of the landscape, but, “I know that nature and people are extremely resilient. That is not to deny climatic thresholds that could put us over the edge.”

He described several forest management practices that can “dictate the terms” so fires can benefit people, water and wildlife:

• The Conservancy, along with the Washington Department of Fish and Wildlife and the Rocky Mountain Elk Foundation, have been acquiring significant pieces of the checkerboard of land in the Central Cascade Range. Connecting the areas will allow for more holistic management; less private ownership means humans are visitors, not residents, he said.

• Forest thinning and controlled burns will reduce the fuel load.

• Roads and culverts must be adapted to the changing water flows.

Edie Sonne Hall, who works in Weyerhaueser Co.’s sustainable forest and products groups, added some additional tactics the giant landowner employs:

• Genetic selection adds not only to a forest’s production but also to its resilience.

• A diversity of genotypes that is maintained will allow adaptation to changing conditions.

Trees will grow differently in a changing climate, such as a longer growing season in sub-alpine areas and less snowpack at lower elevations.

“Subtle changes in precipitation patterns could benefit us,” Hall said, “but warmer winters may help diseases, like Swiss needle cast.”

Thinning dense stands costs money, but the U.S. Forest Service’s budget goes largely to fighting fires.

“One percent of the fires cost 98 percent of the money,” Peterson said. “That’s what we spend all our money on.”

A bill moving through Congress would renew the federal government’s commitment to manage its forests. Rep. Greg Walden, R-Ore., said the legislation would help prevent catastrophic fires, improve forest health and benefit rural communities.


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