Perspectives: When a scientist sleeps at the forest fire’s edge

 Perspectives: When a scientist sleeps at the forest fire’s edge

5 September 2009

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USA —  I’m stressed out and exhausted. My Sierra Madre neighborhood has been blanketed by ash and smoke. We’ve closed up everything and set the air conditioner at 80 degrees, but the smoke smells have seeped in and my sleep has been restless. My nerves and I’m sure many others, are on edge. But, driving into JPL one morning last week, I took a deep breath … cough, cough … and realized how much worse all this could have been. Yep, I might not be driving into JPL, if Santa Ana winds had propelled this mammoth fire out of the Angeles National Forest and into the crowded foothill neighborhoods. Wind-driven and out of control, this immense fire would have been a full-blown disaster.

Below I give some geeky observations of the past week, and our fire history in an attempt to get a scientific perspective.

Once again, Mother Nature has reminded us of how precarious our foothold in beautiful Southern California really is. The day after I was singing the praises of our mild summer, we were whiplashed last Thursday when a crushing high-pressure system settled in over Southern California. Overhead our atmosphere was compressed, causing temperatures to soar into the triple digits, relative humidities to plummet to single digits, and, our worst nightmare, fires to erupt all over our foothills. By the way, who was (were) the nutcase(s) who lit these fires?

What set us up for these fires? Rain has been scarce. A large-scale drought has strangled the American Southwest for almost a decade, four years of below-normal rainfall have parched the Southland, and six months with almost no rain at all have turned our foothills dangerously dry. All this was serious enough, but the catalyst was the dangerous fuel load … much of the surrounding Angeles National Forrest had not burned in 40 to 60 years. It was a question of when we would burn, not if.

The really good news is that the feared Santa Ana winds did not develop. But the bad news was that the atmosphere was eerily still. Immense pyrocumulous clouds, visible all over the Southland, soared into the upper atmosphere. Lacking any strong winds, an acrid fog of ash, stinging and choking smoke and uncertainty of what would happen next engulfed all of us. The smoke, moving out of the fire zone in the early morning and retreating back in the mountains with afternoon “sea breezes” each day, gave little relief to wheezing foothill residents.

We all must be reminded that the history of California is written in great fires. These great fires are an inevitable and natural part of the ecology of the surrounding forests. These fires are followed by a “rebirth” of our forests, stimulating new growth and refreshing the biodiversity. Fires are scary, but they are also normal, and necessary.

We are risk takers, building and encroaching into the wild lands of old-growth brush and steep canyons. Our lifestyles are in serious conflict with our fire-prone environment. Will this scare make us regularly clear defensible areas around our hilltop and canyon homes? Will we pass and enforce stricter fire-resistant building codes? Will we factor in these inevitable fires and rethink where we build? I hope so!

We were flat-out fortunate. Given Santa Anas, many of the foothill communities could have been decimated. But, so far, this fire, while large and menacing, has been slow moving and controllable. Large fires here without reckless, driving winds are rare. Thus far, at least, we have been comparatively lucky.

William Patzert is a climatologist and oceanographer at the Jet Propulstion Laboratory in La Cañada Flintridge.

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