Basically, I see SF as being the big "what if" allowing authors to tell a story and explore the ramifications of that plotline without haveing to be constrained by modern expectations. So, for environmentalism you get the opportunity to explore what possibilites exist and what a change here or there will do to the environment. There is a lot of sub-commentary in a goodly amount of SF regarding the environment.
A lot of the transhumanism work out there is very "green" in its forward thinking and the use of technology to augment nature. Cyperpunk, with its certain dystopian feel, is much less optimistic and usually paints a pretty bleak picture in regards to neature... it really is all in how you spin a future society's interaction with its environment.
Answers to life's biggest questions:
1) Yes it makes a sound! It's a F***ing Tree!!
2) The egg was first.
3) It's the sound of your fingers hitting your palm.