Help me calculate my carbon ass-print.
December 2, 2009 10:46 PM   Subscribe

How much does my flatulence contribute to climate change?

I'm a pretty typical granola liberal -- I commute by bicycle almost all the time, and I eat a lot of legumes. Consequently, I fart a lot. I recently joked that probably the biggest part of my carbon footprint is actually my butt. This, of course, got me thinking: Could it really be? I understand that methane is orders of magnitude more significant than CO2 in contributing to global warming.

Given this data: male, early 30s, 175 lbs, I'd estimate an average of 30 very healthy sized farts per day (I have neither the equipment nor the inclination to obtain a more precise volumetric measurement, sorry)...

What is the estimated environmental impact of my ass as compared to other typical activities? How many commuting miles (city driving, 1998 Toyota Corolla) would I need to replace with bicycling or walking miles to make my digestive tract carbon neutral?

Come on AskMe, I know you like overthinking plates of beans!
posted by dr. boludo to Science & Nature (12 answers total) 7 users marked this as a favorite
Are we talking about the Earth's climate, or the microclimate of the room you happen to be in at the time?
posted by davejay at 10:49 PM on December 2, 2009

Response by poster: Global climate. In measuring the environmental impact on my immediate surroundings, temperature would be the least of my worries.
posted by dr. boludo at 10:53 PM on December 2, 2009 [1 favorite]

It probably does on an aggregate level, all you need to do is look up a few values:

How much methane is produced by the beef industry and how many cows are there to tell you the per capita number. Then just look up how much methane an average (or above average in your case) person produces then youll know.

Car's don't produce methane, but you could still compare it to chemicals that car's do produce (NOx, COx, and HC).
posted by Groovytimes at 11:03 PM on December 2, 2009

After looking at this site I guess I'm wrong on that:
posted by Groovytimes at 11:11 PM on December 2, 2009

Best answer: Methane is only 25 times worse than CO2 (measured over 100 years, more over shorter periods but not "orders of magnitude"). Farts contain 10% methane at most, compared to something near 15% CO2 in car exhaust. So if you produce 1l per day of 7.5% methane, that's equivalent to the exhaust produced by a 2l car engine in 25 revolutions, ie: idling for about 4 seconds.
posted by Canard de Vasco at 11:24 PM on December 2, 2009 [1 favorite]

Wouldn't the negative impact be canceled out by the fresh air created from growing the beans that make you fart?
posted by iamkimiam at 2:09 AM on December 3, 2009 [1 favorite]

[Folks, I deleted a few comments. Its ok to say "farts are negligible" but I think the OP is looking for facts not opinions]
posted by vacapinta at 5:12 AM on December 3, 2009

I'm not sure if this applies to human physiology, but a recent study said that omega 3 fatty acids reduced the amount of methane cows produced. If you have a good amount of omega 3s in your diet (which you probably do, since you sound health conscious), you might be producing less.

Also, cows digest their food largely by fermenting it and chewing it, which is why they have four stomaches and chew their cud. I've heard that it's actually cow burps that produce the most methane. Human digestion is different, so I suspect humans produce much less methane on all scales (ie grams/kg, per capita, per calorie, etc).
posted by mccarty.tim at 6:03 AM on December 3, 2009

I think there was a MythBusters episode about this.
posted by Melismata at 7:42 AM on December 3, 2009

Best answer: According to this study, only 30-62% of humans even produce methane. And the composition of flatus gases doesn't go past 10% in most cases. So no, I can't see your gases being a problem.

My uncle Art's, on the otherhand...
posted by Hardcore Poser at 9:33 AM on December 3, 2009

Canard de Vasco has it. Don't worry about your butt, and if you're a vegetarian the smaller carbon intensity of your diet compared to even a light carnivore more than offsets the potential additional emissions at your backside.
posted by bumpkin at 10:03 AM on December 3, 2009

Response by poster: Thanks folks. This was just idle curiosity, not extreme liberal guilt, for what it's worth. And for the record, climate change notwithstanding I think la dra. boluda would have a very big bone to pick with the notion of my farts being "negligible."
posted by dr. boludo at 10:09 AM on December 3, 2009

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