Imagine that all the people on Earth – all 6.5 billion of us and counting – could be spirited away tomorrow, transported to a re-education camp in a far-off galaxy. (Let’s not invoke the mother of all plagues to wipe us out, if only to avoid complications from all the corpses). Left once more to its own devices, Nature would begin to reclaim the planet, as fields and pastures reverted to prairies and forest, the air and water cleansed themselves of pollutants, and roads and cities crumbled back to dust.
“The sad truth is, once the humans get out of the picture, the outlook starts to get a lot better,” says John Orrock, a conservation biologist at the National Center for Ecological Analysis and Synthesis in Santa Barbara, California. But would the footprint of humanity ever fade away completely, or have we so altered the Earth that even a million years from now a visitor would know that an industrial society once ruled the planet?