I’m sort of piling on at this point, but I can’t help myself. Last week, the Seattle Parks Department set off a small firestorm when they announced a possible ban on beach bonfires. For whatever reason, the press ran the story as a global warming policy. (I’m told that Parks marshalled a number of reasons for the potential ban, only one of which was that bonfires contribute to global warming.) The city has since backed off on the ban, but in all the hullaballo I haven’t seen any treatment of the basic question: how much carbon comes from a bonfire?
Now, everyone seems to agree that bonfires don’t release a lot of climate emissions, but what exactly does that mean?
I’m here to report that a big bonfire might produce the carbon emissions of burning about 10 gallons of gasoline, but probably less (an estimate like this has wide error bars). Different kinds of wood store different amounts of carbon—the calculations are a morass, trust me—and, of course, it depends on how much wood folks throw on the fire. People do like a big bonfire though, so I made this estimate based on the emissions from burning an entire pine tree that was 5 inches in diameter at the height of your chest. (That means the tree might be somewhere around 20 feet tall.)
So I’d put bonfires into the same category as leaf blowers and backyard “carbon sinks“—much too small to worry about. But I think what’s most annoying is the communications. Global warming needs to be addressed with big policy such as a comprehensive carbon tax or with cap and trade. In the Northwest, we’re fortunate that there’s a very encouraging amount of public support for good climate policy. But turning every last thing into a climate issue just annoys people — and it’s counterproductive to getting the big wins that will actually make a difference.
It also tends to distract from the really good work that the city has done on climate. So while there may be other good reasons to ban or restrict urban bonfires, let’s remember that they are basically irrelevant to climate change.
Methodology: I used a metric calculator from Australia, which computes that a 5 inch diameter tree contains about 193.6 pounds of carbon-dioxide equivalent (after making all the necessary conversions). I ballparked a gallon of gasoline at 20 pounds of CO2, a figure that doesn’t factor in lifecycle emissions. (Factoring in these “upstream emissions” would further reduce the significance of the bonfire.) There are a whole range of carbon estimates in wood products, so your mileage may vary.