Tuesday, August 04, 2009

Incremental Veggie-tism II

Okay, to follow up: you don't need to poke around the web too long before finding information about relative carbon intensity of different food groups. See here and here for rundowns of a Carnegie Mellon study (woooo Tartans) from last year. The basic short answer is still "avoid red meat." Transport matters a lot less for carbon output than production does -- like production is over 80% of the total -- so "eat locally" is a lot less powerful than "avoid red meat." As in, "eat locally" is like "avoid red meat one day out of every five." The study itself is readable but requires some time and attention.

"Carbon output" is actually misleading here, because meat/dairy production releases nitrous oxide (fertilizer use) and methane (self-explanatory) in quantities of similar significance to carbon dioxide.

Anyway, to wind towards the first question in my mind, about eggs and dairy: talking greenhouse-gas-per-calorie, eggs, along with chicken and fish, are relatively fine -- actually about where fruits and vegetables are. Cereals & carbs are significantly better. Dairy is somewhat worse, and red meat is twice as bad as that. Here's a deceptively complicated graph from the study; the third grouping from the left is the output-per-calorie comparison. This is all relative to red meat, which is why red meat is always up at 1.

My gut tells me that per-calorie is the most legitimate of the three normalizations they give, but of course my gut is not the gut of a dietitian.


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