Of course you already know. Of course you can merely look out the window and see the traffic and the plastic and the smog and the bad haircuts and the war and the Paris Hilton and the Bush and say, well duh.
But imagine the result anyway. Imagine for a moment that every human on the face of the planet was suddenly whisked away to the divine gurgling ether in one big blast of cheery Armageddon nothingness, all the Bible-waving True Believers carted off to a giant sex-free harp-filled cosmic Wal-Mart while the rest of us leap to the next luminous transformational echelon of timespacelove.
What would happen, really? How would the planet respond if all bipeds disappeared tomorrow?
You can probably guess. Almost immediately, the planet would shudder, shift, align itself anew. Immediately, all endangered species would begin to recover. Light pollution (that is, pollution caused by industrial light) would soon vanish, followed by a great reduction in air pollution, methane gasses, chemicals in fresh water. Soon, all bridges and dams would collapse, roads would become overgrown, buildings would decay, corals would regenerate, most organic landfill would decay and vanish. And that’s just the beginning.