Anthropocene

Abstract

In geological time, the human life span is almost immeasurably brief. The seventeenth-century archbishop James Ussher famously calculated from biblical events that Earth was formed in 4004 BCE; scientists now estimate that the planet is 4.6 billion years old, and that the six millennia since the apocryphal Creation have probably contributed less than 10 millimeters of sediment to the geological record. Geological eras are unfathomable by ordinarily temporal measurements, such as the daily spin of the planet or its annual orbit, leading some scientists to adopt the galactic year—the 250 million terrestrial years it takes our solar system to rotate around the center of the galaxy—as a standard time unit. On that scale, Homo sapiens has been around for less than a week. Yet as the technology to study the planet has improved, so too has the technology to alter it. Earth increasingly disproportionately bears our imprint, as if geological time were being accelerated to the beat of our biological clock, with the consequence that the planet seems increasingly mortal, its legacy and ours entangled. In geological terms we are in the Holocene epoch—a designation formulated from Greek roots meaning “wholly recent,” officially adopted at the 1885 International Geological Congress—and have been in the Holocene for the past ten thousand years. The question, given all that we’ve done to the planet, is whether the label remains valid, or whether we’ve now buried the stratum of our Neolithic ancestors beneath our own rubbish. The atmospheric chemist Paul Crutzen was the first to effectively challenge the conventional geological thinking. In a 2003 interview with New Scientist he recollected the circumstances: “This happened at a meeting three years ago. Someone said something about the Holocene, the geological era covering the period since the end of the last ice age. I suddenly thought this was wrong. In the past 200 years, humans have become a major geological force on the planet. So I said, no, we are not in the Holocene any more: we are in the Anthropocene. I just made up the word on the spur of the moment.