http://blog.newsweek.com/blogs/labnotes/archive/2007/10/25/why-california_2700_s-wildfires-are-america_2700_s-future.aspxI'm pretty conservative about attributing weird weather and other climate anomalies to global warming: all you can say is that a record-setting hot October, or a string of 70-degree days in January in New York, is consistent with what a greenhouse world would be like. But when scientists go on record with a specific prediction of how climate change will play out, and when it indeed plays out that way, attention must be paid.
Last year, a study in the journal Science found that "large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons." The greatest increases were in forests of the Northern Rockies, but was seen throughout the west The pattern of western fires matched what would be expected not from changes in land use--mostly logging and ranching--but from climate change.
Specifically, a warmer world caused by the accumulation of heat-trapping greenhouse gases produces alternating deluges and droughts. The extra heat causes greater evaporation, but the water vapor remains in the atmosphere longer, or travels farther, before falling--in buckets. The result is alternating wet and dry years. In wet years, vegetation grows like mad. In drought years, that vegetation becomes tinder, exactly what southern California is now experiencing. As the scientists said, "an increased incidence of large, high-severity fires may be due to a combination of extreme droughts and overabundant fuels."
And no, it's not just a matter of media attention or the ubiquity of fire video on YouTube. The scientists found that the frequency of wildfires beginning in the mid-1980s was nearly four times that of 1970 to 1986, "and the total area burned by these fires was more than six and a half times its previous level." It's real, and it's going to continue.
...
"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," says Ronald Neilson of Oregon State University, who is also a bioclimatologist with the U.S. Forest Service.