Did global warming fan the wildfire?

Are the massive fires burning across Southern California a product of global warming? Scientists said it would be difficult to make that case...

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.

8220;In Southern California, it8217;s hot and dry much of the year,8221; said Anthony Westerling, a climate scientist at UC Merced and the study8217;s lead author. In other words, Southern California was already perfect for fire.

8220;That is a fire-prone environment regardless of whether we are in a climate-change scenario,8221; said Tom Wordell, a wildfire analyst at the National Interagency Fire Center in Boise, Idaho.

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But eventually global warming could make Southern California8217;s occasional droughts more persistent, exacerbating the fire danger. Conditions as dry as the Dust Bowl of the 1930s could prevail in the Southwest by the middle of this century, according to a study published this year in Science.

The study suggested that the transformation may already be underway. The Southwestern United States has been in drought since 2000, although tree-ring records show there have been far drier periods during the last millennium.

Scientists said more persistent drought would inevitably lead to more fires, as long as intermittent periods of moisture allowed vegetation to grow as fodder for flames.

In Southern California, hillsides were ripe for fire because big rains two years ago allowed vegetation to flourish, then severe drought during the last year dried it out.

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Norman Miller, a climate scientist at Lawrence Berkeley National Laboratories, published an analysis last year in Geophysical Research Letters predicting that rising temperatures, fueled by greenhouse gas emissions, would eventually push peak Santa Ana winds from mid-October to late November.

That could, over decades, make fires worse by giving the landscape more time to dry out. Global warming, he said, could intensify wind flow by increasing the difference between inland and coastal temperatures.