I recently watched "Life After People" on the Discovery Channel (I think). Marcelo had seen it and said I'd like it. After I watched it, while he felt a little worried, I felt strangely reassured.

We can't destroy the planet. Almost no matter what we do, life will go on. Once we've wiped ourselves off the face of the planet, it will recover. That actually makes me feel a lot better.

There was a section of the show where they visit and examine a city that was abandoned after Chernobyl made it uninhabitable. It's recovering quite well, nature is taking it back. It was really fascinating to see this kind of experiment in progress of what would happen if everyone disappeared.