Surprisingly, when it comes to making OJ, it's not the packaging or the trucks--growing the fruit produces the single greatest proportion of the carbon footprint of Tropicana orange juice, as PepsiCo just hired an outside consultant to determine. Citrus growers employ huge amounts of nitrogen fertilizer, which is made from natural gas.

Tropicana, which recently redesigned its cartons and offers a dizzying number of varieties with add-ins from omega-3s to mango, did launch an organically grown brand in 2007; maybe they can start advertising it "Now With One-Third Less Carbon?"