The Daily Green: California Wildfires and Global Warming (study: GW bigger facter on wildfire...

[Harper_is_Bush]

...activity and intensity than forest management)

California Wildfires and Global Warming

Across the West, Major Wildfires are More Frequent and Intense Due to Climate Change

Dan Shapley / News Editor

The wildfires consuming Southern California are extraordinary: Extraordinary because they have claimed so many homes. extraordinary because they started so quickly and have burned so intensely. Extraordinary because they are exhausting the formidable firefighting resources in a region used to wildfire.

But in the years to come, they may become ordinary.

Scientists have already tied increased frequency and intensity of wildfires to the changing climate, and scientists are confident that the conditions that will be brought on by global warming will only make conditions more ripe for wildfire. Forest management practices — like the fire-suppression techniques that left tinder-dry brush and wood littered across the Western landscape.

In a scientific paper published a year ago co-authored by Tom Swetnam of the University of Arizona’s Laboratory of Tree-Ring Research, and Anthony Westerling, of the University of California-San Diego’s Scripps Institution of Oceanography, scientists concluded that the changing climate was a greater influence on wildfire activity and intensity than forest management.

http://www.thedailygreen.com/2007/10/23/california-wildfires-and-global-warming/8086/

Ok, now. Tell me again there's no evidence that any of this is outside "natural variations".

[jdlh8894]

1. Could arson be outside "natural variations" ?

[Harper_is_Bush]

4. That is mentioned in the study. n/t

[mike_c]

2. read Westerling's paper....

The article you linked misrepresents it in the context of the socal fires-- Westerling et al found that climate was likely a bigger factor in mesic high elevation forests than in dry low elevation forests typical of southern California IIRC.

on edit-- here you go, from the abstract: "The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt."

http://www.sciencemag.org/cgi/content/full/313/5789/940

Emphasis is mine.

[Harper_is_Bush]

3. I don't see how that conflicts with the article.

or how that demonstrates the article to be "misrepresenting" the socal fires.

Just because the greatest increases were in "mid-elevation, Northern Rockies forests", it doesn't change the studies observation that earlier/drier spring and drier summers with increased temps are creating conditions for more and more intense wildfires accross Southern California. Further down the studies discusion it says:

"Most wildfires in the Southern Rockies and Southern California have also occurred in early snowmelt years, but again forest area there is small relative to the Northern Rockies and Northern California. Thus, although land-use history is an important factor for wildfire risks in specific forest types (such as some ponderosa pine and mixed conifer forests), the broad-scale increase in wildfire frequency across the western United States has been driven primarily by sensitivity of fire regimes to recent changes in climate over a relatively large area."
http://www.sciencemag.org/cgi/content/full/313/5789/940


K?

edit: that absolutely supports what you objected to in the article. I think you should retract your claim that the article "misrepresents" the studies findings in the context of socal.

[mike_c]

6. I disagree....

From the same paper, two sentences that summarize this entire debate:

"Whether the changes observed in western hydroclimate and wildfire are the result of greenhouse gas–induced global warming or only an unusual natural fluctuation is beyond the scope of this work. Regardless of past trends, virtually all climate-model projections indicate that warmer springs and summers will occur over the region in coming decades."

I have a meeting shortly so I'll have to keep my response brief. Westerling et al correlated fire severity with dry conditions-- not a surprising result-- but they NEVER demonstrated that the drought conditions they cited were the result of global climate change or simply natural variation. The real value of this paper is that it demonstrates that PREDICTED changes in regional drought patterns might have as great an impact as land use patterns such as fire exclusion (or greater in some cases). Again, this is not surprising-- if it gets dry enough, things are more likely to burn. But they did NOT analyze the drought trajectories they correlated with fire frequency and severity-- they offer no evidence that those droughts were anything but natural variation in moisture availability.

Further, they raised the issues of scale dependency and interaction between drought severity and land use history:

"We describe land-use history versus climate as competing explanations, but they may be complementary in some ways. In some forest types, past land uses have probably increased the sensitivity of current forest wildfire regimes to climatic variability through effects on the quantity, arrangement, and continuity of fuels. Hence, an increased incidence of large, high-severity fires may be due to a combination of extreme droughts and overabundant fuels in some forests. Climate, however, may still be the primary driver of forest wildfire risks on interannual to decadal scales. On decadal scales, climatic means and variability shape the character of the vegetation . On interannual and shorter time scales, climate variability affects the flammability of live and dead forest vegetation (13–19, 25)."

Look, I'm NOT arguing that climate change isn't happening or that it isn't having ecological impacts. I'm not arguing that the fires in socal are not influenced by climate change-- they undoubtedly are. Average temperatures across the west have risen by about 1°C. That's a lot of energy and it is likely affecting the timing of snow melt. It is definitely affecting animal migration patterns. What I'm arguing is that it is COUNTER PRODUCTIVE to attribute local weather related events to causes like global warming unless we're certain that they are outside the range of natural variation. There is historical evidence suggesting that is not the case for socal fires.

Damn, I'm getting swamped with interruptions-- got to run.

[Harper_is_Bush]

7. Ok, so you concede global warming is forecasted to result in more and longer drought...

...but we can't point at any particular drought and attribute it to global warming.

I know you're not arguing climate change isn't happening, and apologize if I gave you the impression that I was accusing you of that.

However, I am getting tired of the overly cautious and conservative approach to events that the science demands.

I asked you elsewhere "at what point can we EVER point to climate change as a factor in anything?"
You said "excellent question, the answer to which we are still trying to grapple with".

Well, I'm not going to "grapple" with it anymore. It's time to start calling a spade a spade here, all the conservative scientists be damned.

The great irony is how the deniers and rightwing nuts (ex Beck) accuse the IPCC and the scientists therein of being "alarmists" when in fact the absolute opposite is true. They weren't even willing to include the prospect of increased polar/Greenland melting in their last report. They are conservative to the core in their forecasts.

[kestrel91316]

5. Eventually the chronic lack of water will result in failure of vegetation to

regrow as thickly in the burned areas and they will burn less. Unfortunately this could take hundreds of years....

I read somewhere that even the prickly pear cactus in the desert SW is being adversely affected by the heat and drought.......oy vey.