No rational person can possibly think that humans have not contributed to the global changes happening on our planet. I know my family doesn't do enough, but it's a start. We take public transit when we can, but not if it's really inconvenient, and it often is where we live. We use compact flourescent lights and recycle, but that seems like the bare minimum. We have low flow toilets and showerheads and save our rain water for watering outside during the summer.
Informal conversation seems to indicate that people generally want to help the environment, to do better. But not if it's 'hard'. Not if it's not convenient or puts us out in any way, or costs us money… and I know I fall in that category. I'm trying, but I hope my children do better.