In light of Seattle’s proposal to charge a 20-cent per bag fee on paper and plastic grocery sacks, I thought I’d reprise one of my favorite posts from 2007.

Read the full thing here: Paper versus Plastic—the Final Analysis, written by then-intern Justin Brant. The upshot is that Justin crunched the numbers and found out what’s really going on with our groceries. (And no, the big finding is not that paper is worse. Argh.)

This chart gets to the heart of the matter, by comparing the energy embodied in hypothetical bags of groceries.

I’m not trying to nitpick the policy. I think Seattle’s proposed fee is a fine idea (and it’s something that European countries have been doing for years and years). It’s just worth remembering that by the time you get to the check-out line, you’ve already made the more important choices.