Yeah, environmentalist attitudes towards e.g. GMOs and nuclear power look awfully purity-minded to me. I'm not sure whether I want to count environmentalism/Green thought as part of the mainline Left, though; it's certainly not central to it, and seems to be its own thing in a lot of ways.

(Cladistically speaking it's definitely not. But cladistics can get you in trouble when you're looking at political movements.)