Human activity has transformed the Earth – but scientists are divided about whether this is really a turning point in geological history. By Nicola Davison It was February 2000 and the Nobel laureate Paul Crutzen was sitting in a meeting room in Cuernavaca, Mexico, stewing quietly. Five years earlier, Crutzen and two colleagues had been awarded the Nobel prize in chemistry for proving that the ozone layer, which shields the planet from ultraviolet light, was thinning at the poles because of rising concentrations of industrial gas. Now he was attending a meeting of scientists who studied the planet’s oceans, land surfaces and atmosphere. As the scientists presented their findings, most of which described dramatic planetary changes, Crutzen shifted in his seat. “You could see he was getting agitated. He wasn’t happy,” Will Steffen, a chemist who organised the meeting, told me recently. What finally tipped Crutzen over the edge was a presentation by a group of scientists that focused on the Holocene, the geological epoch that began around 11,700 years ago and continues to the present day. After Crutzen heard the word Holocene for the umpteenth time, he lost it. “He stopped everybody and said: ‘Stop saying the Holocene! We’re not in the Holocene any more,’” Steffen recalled. But then Crutzen stalled. The outburst had not been premeditated, but now all eyes were on him. So he blurted out a name for a new epoch. A combination of _anthropos_, the Greek for “human”, and “-cene”, the suffix used in names of geological epochs, “Anthropocene” at least sounded academic. Steffen made a note. Continue reading...