Should the geologic definition of the Anthropocene be formalized?

Prof. Jed O. Kaplan says “No” in the latest issue of the Swiss National Science Foundation’s quarterly magazine Horizons. Read below or click here for the PDF.

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“No” says Jed O. Kaplan of the University of Lausanne.

While ‘anthropocene’ is a valid political concept, it requires no formal definition or stratigraphic ‘golden spike’. As the lower-case ‘anthropocene’, it acknowledges the contemporary observation that human activities are now as important as variations in the Earth’s orbit around the sun, or plate tectonics as an ultimate driver of Earth’s system processes. It is important to recognise that humanity’s actions have consequences for the planet that are truly global in extent and may be leading to changes in ecosystems, landscapes and climate that are effectively irreversible on geologic timescales. On the other hand, a capitalised ‘Anthropocene’ epoch as part of the geologic time scale is not only problematic to define without any hindsight, it is wholly unnecessary.

The geologic time scale was a triumph of 19th-century science, but it has largely been supplanted in scientific and educational value by absolute radiometric dating. Lacking any method for absolutely dating events in earth history, early geologists presumed that rock layers containing similar fossils must have been laid down at about the same time, and the first geologic time scale containing the divisions of time still used today was developed by 1850. Transitions between geologic epochs were defined by the first appearance of certain fossils that could be observed in strata at a number of localities. The boundary between one geologic epoch and another is marked at a specific locality with a ‘golden spike’, literally a plaque or other marker identifying the transition in the rock layers. Much of the recent discussion and debate around defining an Anthropocene has therefore centred around where to place the ‘golden spike’ defining the beginning of our epoch.

However, most modern scientific and even lay literature does not refer to stratigraphic epochs when defining events, except in an introductory sentence. Few people beyond geology undergraduates have memorised the order and variable length of the epochs of the geologic time scale, but it is immediately obvious to any reader that the extinction of the dinosaurs about 65 million years ago happened long before the evolution of modern humans, about 200,000 years before the present.

Beyond being fraught with problems of perspective: how can we define an epoch in which we are currently living and without an obvious endpoint? The concept of the Anthropocene epoch is completely unnecessary in modern science. Even without it we can precisely date the successive influences of humans on the Earth’s system, from our evolutionary beginnings to the present.

Jed O. Kaplan is a professor at the Institute of Earth Surface Dynamics of the University of Lausanne. He studies environmental history and the interactions between humans, land cover and climate.