I agree with about 95% of this:

http://scienceblogs.com/gregladen/2011/06/why_is_anthropogenic_global_wa.php

What the 5% is I don't agree with, and why, the why being more important than the what, I will leave for you to figure out. The Real Climate link is good for real, fact and evidence based, scientific, as opposed to making up stuff that will end up where you wan to go, knowledge. It is complicated, but the basics are very simple.

This is a test of us as a species. How we handle this, or fail to handle it will tell us if we are a mature species, capable of living within its means and cleaning up after itself, or still children who can't muster the grit and attention span to balance an ecological checkbook. No worries, if we don't do it the planet will balance things out for us in its own bloody and heartless way through famine, war and pestilence.