Guardians of the world's official geological time scale have flatly rejected a proposal to declare an Anthropocene epoch after an epic academic row.
The proposal would define the period since 1952 as the Anthropocene to reflect humanity's impact on the planet. This would end the Holocene Epoch, 11,700 years of stable climate since the last Ice Age, during which human civilization arose.
However, the International Union of Geological Sciences (IUGS) announced that geologists rejected this idea in a series of votes. Objectors noted a much longer history of human impact on Earth, including the origins of agriculture and the Industrial Revolution, and concern about the inclusion of a new unit on the geologic time scale that spans less than one human lifespan, he said. Most units span thousands or millions of years.
It also admitted: “The concept of the Anthropocene will continue to be widely used not only by Earth and environmental scientists, but also by social scientists, politicians and economists, and by society at large. As such, it will remain an invaluable descriptor of human-environment interactions.”
The proposal was developed by the Anthropocene Working Group (AWG), established by the Subcommittee on Quaternary Stratigraphy (SQS), part of the IUGS. It was concluded that the radioactive isotopes spread around the world by hydrogen bomb tests were the best indicator of humanity's transformation of the planet. Geological units of time also require a specific location to define the unit, so Crawford Karst Lake in Canada was chosen.
In February, the SQS vote rejected the proposal by a majority of 12 to 4, but its chairman, Professor Jan Zalasiewicz of the University of Leicester, who supported it, said the vote was not in accordance with the rules. However, IUGS has now announced that in the next stage of the process, the chairs of the 17 subcommittees approved the negative SQS vote almost unanimously, with 15 votes, one abstention and one no vote. There is no appeal against this final decision.
“Although the proposal was soundly rejected, the AWG has performed an important service to the scientific community by collecting a broad set of data on human impacts on global systems, and this database will be an important source of reference well into the future.” – said IUGS.
Zalasiewicz said: “The IUGS ruling means that the Anthropocene will continue to confusingly represent very different concepts. This is a missed opportunity to acknowledge and support the clear and simple reality that our planet abruptly and irrevocably left its natural functioning state in the mid-20th century. This is reflected in countless geological signals.”
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The row will probably continue. Zalasiewicz said AWG is preparing a detailed response to “serious inconsistencies” in the IUGS statement that will “simplify the facts.” He also said he would continue to work beyond IUGS to “stabilize the meaning of the term and concept so that it is useful to the broader community.”
One possibility is that the Anthropocene could be called an event – an informal term that geologists already use to describe major changes to the planet, such as the flooding of its atmosphere with oxygen by photosynthesizing cyanobacteria 2 billion years ago and the explosion of complex life early in the Cambrian period 540 millions of years ago.
