Chaparral & Global Warming Footnotes

On October 24, I published the blog Global Warming Not Behind SoCal Fires. Many readers disagreed passionately, and I found myself, a card-carrying Sierra Club member and longtime Al Gore fan, in the odd position of being urged to go to "Republican fact-check school." Interestingly, the next day Los Angeles Times writer Alan Zarembo published a piece called "Global Warming Not A Factor In Wildfires."

Certain critics didn't read my piece carefully, and thought that I was another global-warming skeptic. No, I'm not on Michael Crichton or Rush Limbaugh's team. I believe global warming is a threat, and probably has been a factor in wildfires sweeping through drought-stricken conifer forests in recent years. My blog, however, was specifically about the chaparral brushland of Southern California, not about pine, fir and cedar forests of the West. There is a big difference, as locals know (or should know). We're talking about manzanita, ceanothus, laurel sumac, chamise, scrub oak, and the other thorny scrubs that grow on the hills and up to about five or six thousand feet in the local ranges. In my blog, I argued that "the blame for the conflagrations should be placed on chaparral, a growing population, and inadequate suburban planning."

I am a Pasadena native who has hiked in Southland mountains for decades (I moved out of L.A. recently, but still return and hit the trails). In 1979, as a journalist working for a local paper, I hiked with a Forest Service employee through a burn area in the San Gabriel Mountains above Pasadena. I later became better acquainted with the "fire ecology" of chaparral when I profiled Dr. Jon Keeley, then a biology professor at Occidental College, for a lengthy cover piece for the L.A. Reader in 1981. At that time he commented, "You basically can only postpone the fires in any given area. Chaparral is going to burn. We either just learn to accept it and expect to get our houses burned down once in a while, or we try to do some organized land planning, so that urban sprawl doesn't continue to scatter houses throughout the chaparral."

Chaparral is dangerously flammable during Santa Ana wind episodes, which typically occur in the fall, after Southern California's hot dry summers. Many chaparral shrubs contain flammable oils and resins in their leaves, and their small branches add to their flammability. The age of the brush and small trees is critical, as it determines the amount of potential fuel and the ratio of dead fuel to live plant material (the older the chaparral, the more dead material). Any chaparral patch that has not burned for thirty or forty years has potential for a catastrophic fire. Chaparral age (in decades) is a key component of massive wildfires, as are rainfall patterns over a long period. Fire suppression strategies are also important, such as letting small fires burn themselves out and using controlled burns to reduce the overall danger.

Although the record low precipitation of 2006-2007 created prime conditions for the current disaster, it doesn't have to get that dry before giant brushfires can erupt. In October, 2003, Southern California wildfires burned over 740,000 acres, with 95% of the burn occurring in chaparral and coastal sage shrub areas, according to the Center for Biological Diversity. Rainfall in downtown L.A., at least, was an above-average 16.49 inches in the 2002-2003 season.

If the highs and lows of precipitation in Southern California get more extreme in coming years, then we may be able to conclude that global warming is having an effect on the local climate. Yet, it hasn't yet had a significant impact. Although L.A. had record low precipitation in 2006-07 and a near record high in 2004-05, those numbers are not unexpected in the area's erratic rain pattern. Southland rainfall has always fluctuated wildly, which is clear if you look at the data at the NOAA (National Oceanic and Atmospheric Administration). The rainfall of the last five seasons (16.49, 9.25, 37.25, 13.19 and 3.21 inches) is not that unusual when compared with the highs and lows of other five-year stretches in the past, and the average of 15.9 for 2002-2007 is close to the 15.11 average for 1877-2005.

Even if one believes that the heavy rain in '04-'05 and drought in '06-'07 were significant, rain totals for just two seasons don't prove anything. And I used that same reasoning in a blog I wrote about biofuels and the Amazon rain forest. The Brazilian government brags that the rate of Amazon deforestation declined the last two years. It did. But so what? It doesn't mean it will continue that way. Two years do not make for much of a trend.

Some speculate that global warming could impact the Southland in the future if it makes rainfall patterns more extreme or if it pushes peak Santa Ana winds later in the fall. The latter point was raised by Zarembo in his L.A. Times piece. He quoted climate scientist Norman Miller as saying the delayed Santa Anas could "make fires worse by giving the landscape more time to dry out. Global warming...could intensify wind flow by increasing the difference between inland and coastal temperatures." We'll see if that occurs in the future.

Yet, whether or not the rain totals get more extreme, we keep coming back to the biggest factor in catastrophic wildfires: the amount of fuel that is out there to burn. And that is connected to a long-term rainfall patterns. Global warming could play a role if it causes overall Southern California rainfall to increase, but that hasn't yet happened.

In the meantime, we have millions of people living next to chaparral areas that have always burned with regularity. Let's put the focus where it should be: suburban planning and fire prevention strategies.

And I'm on the side of John Muir. Just for the record.

Comments

[Newfycrat]

I agree with you that these fires are mostly due to bad fire policies. I took a class that focused on the Chaparral zone and we learned all about how it needs fire to stay healthy.
But, I have to again say that the weather conditions in the last two years were unusual. I agree that two years cannot point towards any long term trends, but it is also true that people are reporting that for southern California the global warming models show that there would be increases in rainy periods followed by drought.
So two years ago they got the second wettest season on record (and wettest in over a hundred years) that led into the hottest July on record, with a heat wave that killed hundreds of people, followed by the driest season on record.
When it comes to plant growth, one cannot speak to averages. If a farmer has a dry year it can ruin all his crops as well as a super wet year.
Many people were speaking openly about how much the high rain fall could effect the fire season. A lot of growth means a lot of fuel. A lot of rain could also mean more non native plants take hold which may or may not give more fuel to fires.
So while, I do agree that this mostly has to do with fire management, future generations may have to deal with more frequent high rain years followed by lower rain years and figure out how or if it will change fire predictions.

[kevinabt]

Good post. Its good to see that you can re-enforce your defense of the claim that global warming was not a factor in the wild fires. Althought in my opinion it didn't seem necessary that you had to write another whole article about it, your first one made enough sense that no one should have been up in arms about it.

[realitytrumpsbull]

I'd say that at least some of whatever grievance
there is to be had falls on the desk of the
real estate developers, also on the part of
people building homes that were less than
fire-resistant, and even if your house isn't
all that burn-proof, you can make it that
way by building things like adobe walls,
re-roof the house with adobe shingles,
matter of fact if you just used reinforced
adobe you'd probably have something fairly
earthquake­-resistant too. I think it's pretty
hard to burn concrete, too, and they say that
when they put that stucco stuff on the outside
that it helps a lot. Imagine if they could
develop something like a fire fence, not unlike
a snow fence, but some kind of wire mesh stuff
that didn't cost too much to produce to prevent
embers from spreading etc. Heck, the cheapest
fire prevention of all would be to put a
sprinkler on the roof of your house, that kind
of stuff.

[jay1975]

Stop, you are making too much sense.

[Jane]

I believe you.

What about Big Sur?