My Uncle was a gay card-carrying-Communist: seriously, he'd take out his Communist card and show anyone. He was also a fan of the Sierra Club. I learned early in my youth that this coupling of far-left movements was not the exception but more the norm. It turns out if you hate civilization, and you want to slow it's development, then putting the government in charge of everything (means of production, land, breeding, etc), is a great way to stunt that development. So environmental groups and Communism go hand in hand.
- John Muir (who the Sierra Club was inspired by) was an unapologetic racist.
- The Founder (David Brower) was a eugenicist and technophobic
- The Sierra Club is for policies like government enforced controls on population and the Precautionary Principle.
Basically, the Precautionary Principle is everyone has to prove there's no unintended consequences before implementing or selling anything. This is the idea that in the words of Brower is, “All technology should be assumed guilty until proven innocent,” especially things like GMO's or anything that betters humanity. And they can always think of things for you to disprove, longer than you can stay in business.
Politically, it's hard to say "no", but it's easy to say, "we should test this more before releasing it".... when practically they mean the same thing. Obama (the community organizer) used this technique for pipelines and drilling, "we'll get back to you on that", meant, "Never, but we're too chickenshit to say it". Sierra Club is all in on that.