Full Vegetarian Diet: 1 Ton

Going from an average meat-eating U.S. diet, where 47 percent of your calories come from animal products, at 2.52 tons of carbon dioxide emissions per year, to a lacto-ovo (dairy and eggs allowed) vegetarian diet where 25 percent of your calories come from animal sources, will drop you down to about 1.5 ton of emissions per year, saving about 1 ton per year.

Of course, these numbers are going to be a little different for everyone, depending on where you live, what your current meat/animal product consumption is, where you food comes from, and so forth, but there's no mistaking it: Going vegetarian represents a significant step in the green direction.