Alan Weisman, an associate professor of journalism at the University of Arizona, wrote a book entitled The World Without Us, imagining a scenario where all the world’s people suddenly dissapeared. What would happen to the earth?
According to Weisman, large parts of our physical infrastructure would begin to crumble almost immediately. Without street cleaners and road crews, our grand boulevards and superhighways would start to crack and buckle in a matter of months. Over the following decades many houses and office buildings would collapse, but some ordinary items would resist decay for an extraordinarily long time. Stainless-steel pots, for example, could last for millennia, especially if they were buried in the weed-covered mounds that used to be our kitchens. And certain common plastics might remain intact for hundreds of thousands of years; they would not break down until microbes evolved the ability to consume them.
Link -via Gothamist
(While the Scientific American site is down, here's the link to the Gothamist article.)