Thanks, Juergen, for bringing my attention to this. Paul Hawken is a curious character: basically a businessman and entrepreneur who also has strong interests in environmentalism and social justice, a very rare combination!

There seem to be three distinct reasons why people who had been eating meat and other animal-sourced foods resolve to stop eating them, or at least reduce their consumption of them: 1. concern for the environmental damage (of several kinds) caused by the eating-animals industries; 2. concern for one's personal health; and 3. concern for justice for nonhuman animals. By your account, Hawken's reason is the first.

And that's fine: a commitment to environmental ethics is a *true* pro-life cause. The raising of cattle has been identified as a major producer of greenhouse gases; plus cattle require lots of water. Farmed pigs and chickens create horrible pollution. And there is no truly "sustainable" fishing; modern methods are destructive of marine ecosystems.