I think Jean wrote a wonderful article, and I love seeing all the discussion.
Anybody that thinks we as humans do not contribute to climate change is simply deluding themselves. The question is degree, not if. We have contributed to climate change for a long time. See the deforestation of Easter Island as an example.
So. I'll let everybody else argue the exact degree, but I'll say this. If we as humans continue to foul our own nest we will soon have no place to go home to. It's that easy.