So you've got your free-range turkey. Your potatoes are strictly heirloom varieties. The cranberries for your sauce come from the local organic bog. Feeling pretty good about your Thanksgiving dinner, are you? Not so fast: The environmental footprint of food isn't always what you'd expect. Last Thanksgiving, PBS Need to Know took a hard look at the subject, from a diverse range of perspectives. In its podcast, which is definitely worth another listen, we hear from geophysicist Gidon Eshel, NASA agronomist Cynthia Rosenzweig, best-selling author Anna Lappé, agricultural analyst Philip Thornton, and animal rights activist Tara Oresick.