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Are the fires sweeping Southern California part of climate change?

Posted by: Maven on October 25, 2007 at 5:36 am

From the Science Daily website:

The catastrophic fires that are sweeping Southern California are consistent with what climate change models have been predicting for years, experts say, and they may be just a prelude to many more such events in the future — as vegetation grows heavier than usual and then ignites during prolonged drought periods. “This is exactly what we’ve been projecting to happen, both in short-term fire forecasts for this year and the longer term patterns that can be linked to global climate change,” said Ronald Neilson, a professor at Oregon State University and bioclimatologist with the USDA Forest Service.

“You can’t look at one event such as this and say with certainty that it was caused by a changing climate,” said Neilson, who was also a contributor to publications of the Intergovernmental Panel on Climate Change, a co-recipient earlier this month of the 2007 Nobel Peace Prize. “But things just like this are consistent with what the latest modeling shows,” Neilson said, “and may be another piece of evidence that climate change is a reality, one with serious effects.”

The latest models, Neilson said, suggest that parts of the United States may be experiencing longer-term precipitation patterns — less year-to-year variability, but rather several wet years in a row followed by several that are drier than normal.

“As the planet warms, more water is getting evaporated from the oceans and all that water has to come down somewhere as precipitation,” said Neilson. “That can lead, at times, to heavier vegetation loads popping up and creation of a tremendous fuel load. But the warmth and other climatic forces are also going to create periodic droughts. If you get an ignition source during these periods, the fires can just become explosive.”

To read the full text of this article from Science Daily, click here.

But hold on. Are fires a sign of climate change? Not everyone thinks so. From the Los Angeles Times:

Are the massive fires burning across Southern California a product of global warming? Scientists said it would be difficult to make that case, given the dangerous mix of drought and wind that has plagued the region for centuries or more. But they said the extreme conditions that stoked the wildfires could become more common as the world warms.

Research suggests that rising temperatures are already increasing fire damage in many parts of the West. In a study published last year in the journal Science, researchers looking at Western federal forests found nearly seven times more land burned from 1987 to 2003 than in the previous 17 years. The analysis mainly attributed this to a 1.5-degree rise in average spring and summer temperatures. With spring arriving earlier and snow melting faster, the forests dried out sooner, extending the average fire season by more than two months.

The study, however, found Southern California was different from the rest of the West, with no increase in the frequency of fire as temperatures rose. “In Southern California, it’s hot and dry much of the year,” said Anthony Westerling, a climate scientist at UC Merced and the study’s lead author. In other words, Southern California was already perfect for fire. “That is a fire-prone environment regardless of whether we are in a climate-change scenario,” said Tom Wordell, a wildfire analyst at the National Interagency Fire Center in Boise, Idaho. “I don’t want to be callous, because many people are homeless and suffering, but if you live in a snake pit, you’re going to get bit.”

To read the full text of the article from the Los Angeles Times, click here.

The San Francisco Chronicle also has an article asking this same question:

The 16 wind-blown fires that forced the largest mass evacuation in California history may or may not be the result of climate change, but studies have shown that the hot drought conditions that fed the flames are becoming more common. “Fires are burning hotter and bigger, becoming more damaging and dangerous to people and to property,” U.S. Forest Service Chief Gail Kimbell said. “Each year the fire season comes earlier and lasts longer.”

The flames stretching from Malibu to the Mexican border struck during the driest year in Southern California history. Measurements taken by the California Department of Forestry and Fire Protection detected less than 10 percent moisture in the region’s vegetation. The moisture level in kiln-dried lumber is generally 12 percent. “They got less rain than they’ve ever gotten,” said Hugh Safford, a Forest Service ecologist. “Any time you have a dry year like this one, you are going to get fires.”

The San Francisco Chronicle article also adds this:

Sources of ignition will increase, according to a study issued earlier this year by NASA. It predicted lightning will increase about 6 percent as the amount of carbon dioxide – the most abundant global warming gas – doubles.

To read the full text of the article from the San Francisco Chronicle, click here.

October 25, 2007 · Filed Under General Water Issues

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