Same source. Humanism. Rejection of God, and worship of the creation (see Romans 1).
Warmists believe that humans are just another evolved-from-goo critter and therefore shouldn't be using more resources from the planet than any other evolved-from-goo critter. Warmists also need a "reason to be" since they are nothing special. "Saving the erf" is their "reason to be", it's why they matter.
Good and accurate analysis in http://www.freerepublic.com/focus/news/2768279/posts?page=10#10
Thank you.