Unfortunately, Greek yogurt is supposed to be bad for the environment, too. Here is an article:
Whey-ing Greek yogurt’s environmental impact – Eatocracy - CNN.com Blogs
Huh. According to that article, Greek yogurt producers do not dump acid whey into the environment like my hippie sister indicated, they give it to farmers, who use it for a variety of uses.
I thought this was relevant, but it turned out to be trivial. Please pardon the interruption.