Global Climate Change: Ill-Wind For California Wildfires

"In most cases, climate change would lead to dramatic increasesin both the annual area burned by California wildfires and thenumber of potentially catastrophic fires -- doubling these lossesin some regions," the researchers conclude. "These changeswould occur despite enhanced deployment of fire suppressionresources, implying that climatic change could precipitate anincrease in both fire suppression costs and economic losses dueto wildfires."

Commenting on the study, U.S. Energy Secretary Bill Richardsonsaid, "This study is indicative of the mounting evidence that thepotential effects of climate change can be wide-ranging and verycostly."

Other parts of the country might be just as vulnerable asCalifornia, according to Margaret Torn of Berkeley Lab’s EarthSciences Division, one of the three scientists who conducted thestudy. "Our analysis shows how big an impact climate change canhave, and suggests that future climatic conditions in other partsof the United States warrant concern and study," she said.

The other scientists who conducted this study were Evan Mills,with Berkeley Lab's Environmental Energy Technologies Division,and Jeremy Fried, an associate professor of forestry at MichiganState University. The study was sponsored by the U.S.Environmental Protection Agency.

Nearly 85-percent of all catastrophe-related insurance payoutsresult from natural disasters, with claims averaging about $10billion per year worldwide over the past decade. Wildfires areamong the most pervasive of all the natural disasters, especiallyfor California. According to studies by insurance agencies, ofthe 38 costliest U.S. wildfires between 1825-1995, 22 were inCalifornia. The state also ranks number one in terms of economiclosses due to wildfire.

"These insurance exposures are increasing precipitously as humandevelopments encroach further and further into the urban/wildlandinterface," Says Mills. "The $2 billion Berkeley/Oakland hillsfire of 1991 is a notable example."

Fire danger has long been linked to climate, with hot, dry spellscreating the highest risk. Concerns over the consequences ofglobal warming were rekindled this year by the impacts of ElNiño. Droughts linked to El Niño were followed by widespread,devastating fires in Florida, Indonesia, and elsewhere.

"The latest predictions suggest that global warming may alsocreate conditions that intensify wildfire danger, by warming anddrying out vegetation, and by stirring the winds that spreadfires," the Berkeley Lab researchers say in a report on theiranalysis. "Faster fires are much harder to contain, and thus aremore likely to expand into residential neighborhoods, incurringsubstantial damage to insured property."

To evaluate the potential effects of global climate change onwildfire damage in California, the research team of Torn, Mills,and Fried combined local weather and fire data, validated fireand fire suppression models, and state-of-the-art generalcirculation models of global climatic change.

"We tested the case in which emissions of the most importantgreenhouse gas, carbon dioxide, double their pre-industriallevels - a state of affairs projected to materialize over thenext five or so decades," says Torn.

Three regions in Northern California were examined, Santa Clara,the Sierra foothills, and Humboldt. Each features a distinctclimate, and, together, harbor most of the vegetation types foundin the American west, including grass, chaparral (scrub orbrush), oak savanna, and mixed conifer and redwood forests.

Taking a conservative approach, the researchers only reported theresults based on the climate change model that, out of twotested, predicted the least impact on wildfire. This model, fromthe Goddard Institute for Space Sciences, provides standardscenarios for climate change impact assessments used bygovernment and university scientists around the world.

"Climate change would cause fires to spread faster and burn moreintensely in most vegetation types," the researchers concluded intheir report.

These faster, hotter fires could be expected to frequently escapecontainment, despite increased fire suppression efforts. Thiswould result in many more acres being burned than under thecurrent climate.

"The biggest impacts are seen in grass vegetation, where thefastest spread rates already occur," says Fried. "In forests,where fires move much more slowly, projected impacts are lesssevere."

In their modeling, Torn, Mills, and Fried found that the mostsevere effects of global climate change were inflicted on theSierra foothills where the predicted number of potentiallycatastrophic fires increased by 143 percent in grassland and 121percent in chaparral.

"With the number of escaped wildfires more than doubling,climatic change could lead to a significant jump in fire damagein this region," the researchers reported.

In the Santa Clara region, the number of escaped wildfiresincreased by 53- and 21-percent respectively in grassland andchaparral. Only in Humboldt, the third region examined, which ischaracterized by redwood forests growing in moist, foggy areas,was there little change in wildfire damage as a result of climatechange. Even here, however, the analysis projected thatfire-fighting costs would increase as a result of more intensefires.

Results of this analysis are being shared with the CaliforniaDepartment of Forestry which has been cooperating with theBerkeley Lab researchers throughout.

Says Torn, "The CDF provided us with all of the fire andanalysis-zone data we used and kept us informed about modelupdates. They have now begun to devote some time to this topicthemselves."

Berkeley Lab is a U.S. Department of Energy national laboratorylocated in Berkeley, California. It conducts unclassifiedscientific research and is managed by the University ofCalifornia.