Are you ready for the Anthropocene?
Most geology textbooks will tell you that we are living through the Holocene Epoch. And the way they work it out is this:
About 545 million years ago (give or take), the Phanaerozoic Eon began when hard-shelled invertebrates started to appear among all the squidgy worm-things which constituted the population of Planet Earth in Precambrian times.
The Phanaerozoic divides into three eras: the Palaeozoic, the Mesozoic and the Cenozoic which began about 65 million years ago when the dinosaurs all died out. The Cenozoic Era then divides into three periods: the Palaeogene or Lower Tertiary, the Neogene or Upper Tertiary and the Quaternary which began about 2.5 million years ago when recognisable humans first appeared. And the Quaternary Period in turn divides into two epochs: the Pleistoscene and the Holocene, which began about 12,000 years ago after the retreat of glacial ice from North America. Give or take.
Back in 2000, geologist Paul Crutzen, a Nobel Laureate from Mainz University in Germany, proposed that humanity’s effect on the planet constituted a third Quaternary epoch – the Anthropocene, beginning in the late 18th century. Now Crutzen has teamed up with Jan Zalasiewicz and Mark Williams from our Department of Geology (plus Will Steffen, Director of the Australian National University’s Climate Change Institute) to argue the case for the Anthropocene in the new issue of the American Chemical Society’s journal Environmental Science & Technology.
Crutzen et al claim that human-related factors such as sprawling urbanisation, use of fossil fuels, widespread extinctions and massive population growth have rendered the last couple of centuries sufficiently different to the previous 11,800 years to constitute a new geographical epoch. This is a contentious issue in geographical circles right now but the four authors point out in their commentary (online from 29 March, in print from 1 April) that the matter certainly warrants discussion.
The extent and definition of all these various eras, eons and epochs is governed by the International Commission on Stratigraphy who have a detailed Geological Timechart PDF available on their website. A simplified Geological Timechart can be found among the Education Resources on the British Geological Survey website.