Sandwiches can save the planet

This made me laugh today. Apparently you can save the planet by eating peanut butter and jelly sandwiches instead of meat-based meals. The folks at PBJCampaign say those burgers cost too much in terms of water, carbon dioxide emissions and forest cover.

But I wonder where the peanuts in my PBJ come from, and how many miles they flew to get here. Likewise my jam. And how much water did the fruit and nuts need in order to reach my kitchen?

Just reassure me that a PBJ does less damage to the planet than a burger or a pizza and I'll sign up.