YUP, just as I thought, we're responsible, at least in part. there might be a cyclical thing going on, but we're pushing it over the edge. The combination of all factors spells disaster. It's time to start the greening process. First, we need an all out thermonuclear war to thin the herd, this would eliminate 2/3 of the problem (Humans), then the earth could go through a regeneration period and the space aliens could come by in a few thousand years and re-seed the population and we could start over. Hopefully this new species wouldn't be the warmongering breed that now inhabits the planet. Or we could try and get a handle on the situation we have now. Basically, it's up to us.