The edges of historical eras tend to be fuzzy. It would be nice to think that someone awoke in Florence, Italy, one day in the late 1300s — perhaps as spring started— and said, “Today the Renaissance begins!” We can be sure no one did, if only because historians discern such eras only in retrospect. The same is true of geological epochs. Humans existed when the Pleistocene ended and the Holocene began, 11,500 years ago. The geologic time scale, which defines geological periods, began to take its modern form only in the 19th century.
Among scientists, there is now serious talk that the Holocene has ended and a new era has begun, called the Anthropocene, a term first used in 2000 by Paul Crutzen, who shared a Nobel Prize for his work on the chemical mechanisms that affect the ozone layer.
The Royal Society has devoted a recent issue of its Philosophical Transactions to the Anthropocene. According to one of the papers, the name is “a vivid expression of the degree of environmental change on planet Earth.” It means that human activity has left a “stratigraphic signal” detectable thousands of years from now in ice cores and sedimentary rocks.
via The New York Times