

For every acre of California forest that burns in this week's 1,000 blazes, about 17 tons of carbon dioxide are being released into the atmosphere.

With an estimated 265,000 acres scorched already, these fires could have already sent up to 4.6 million tons of CO2 into the atmosphere.

That's as much CO2 as a mere 9 days' worth of California traffic generates, according to our back-of-the-envelope estimate. (See the end of the post for details and caveats.*)

Last October, during California's last bout with wildfires, NCAR scientists calculated that the 500,000 acre blaze pumped 8.7 million tons of carbon dioxide into the atmosphere, or 17.4 tons per acre.

Noted AP writer Seth Borenstein noted that this emissions tally was equal to human activities in California for a week. Many people responded to this news by saying, "Wow, those fires are big." Borenstein even noted that the wildfire emissions were greater than the state of Vermont's for a year.

Somehow, the more interesting, inverse point was lost: Human activity in California, from an emissions perspective, is like a massive wildfire every single week.

That shouldn't be a surprise, considering that cars and power plans both burn ancient biomatter. That gas in your tank? In energy terms, it's the equivalent of 200 pounds of wood!

Of course, the fires, unlike your gasoline-powered car, produce huge amounts of particulate matter, aka soot, which are making San Francisco's air look like Beijing's. The most recent fire, using particulate emission factors (.pdf) calculated by another group of scientists, could have already produced 40,500 tons of PM. That's bad news for your lungs, if you happen to live in northern California. Last year, the state estimated that lowering diesel emissions would annually prevent 6,500 premature deaths, and all of the diesel engines in California only produce about 27,000 tons of the stuff a year.

* We calculated a per-acre carbon dioxide number of 17.4 tons from the emissions calculations carried out last year by NCAR scientist Christine Wiedinmyer and UC-Boulder professor Jason Neff. This was a higher CO2 estimate than California's Air Resource Board estimate of 12 tons per acre for the same fire. We calculated the California traffic CO2 numbers from the Air Resources Board's 2004 emissions inventory, located here. In 2004, all on-road traffic generated 188 million tons of CO2 or 468 thousand tons a day.

Image: Courtesy NASA's Earth Observatory. Snapped June 25th. High-res version.

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