975.  Rejection of "Anthropocene" Geologic Age Proposal

Since the 1950s, scientists have been working to define a new geological era, the "Anthropocene," in which human activities have begun to affect the entire planet. Last July, a working group of the International Union of Geochemistry (IUGS) selected Crawford Lake, Canada, as the candidate "International Standard Model Section and Locality" for the new geologic epoch of the Anthropocene. However, the IUGS subcommittee has now reportedly rejected the "Anthropocene" proposal.

Editorials in Nature and Science, noting the rejection of the proposal after 15 years of controversy, commented that scientists were not denying the accelerating effects of climate change and biodiversity loss, but that there was a need for a deeper and broader discussion of human impact on the Earth.　

The Anthropocene proposal, if adopted, would have marked the beginning of the Anthropocene in the 1950s and the end of the Holocene since the Ice Age 11,700 years ago, based on the discovery of traces of plutonium, fossil fuels, pesticides and fertilizers from the hydrogen bomb in a 10-centimeter layer of sediment in Lake Crawford.

However, there are many ways in which humans have impacted the Earth system, including the beginning of agriculture, European overseas expansion, the Industrial Revolution, and many others, and many scientists have argued that the definition should be broader than the current definition of the Anthropocene. Rather, given the long-term evolution of human impacts on Earth, a more appropriate definition of the Anthropocene is as the Great Oxidation Event (the beginning of the rise in oxygen levels that triggered the emergence of complex cells, animals, and humans more than 2.3 to 2.5 billion years ago). Some have argued that a deeper and broader definition should be attempted by considering the Anthropocene as an "event" in geologic history, rather than identifying it strictly as a geologic epoch.

Both Nature and Science editorials noted that some committee members objected to the rejection of the resolution because of problems with the voting process, but also noted that even if the Anthropocene is not recognized as a new geological epoch, it is already widely recognized as an informal concept.

Contributor: IIYAMA Miyuki (Information Program)