A long-standing effort to formally place the Anthropocene on the geologic timescale came to a surprising end this year. In March, a panel of academics rejected the proposal to define a new epoch by 12 to 4 votes. Yet for the team behind the proposal, work on defining the term – which highlights rapid, human-induced changes to Earth – continues.
As it stands, the Holocene, which began about 11,700 years ago, remains the current epoch. It broadly covers a period of planetary stability during which human civilisation flourished. However, some scientists believe that the increasing impact on Earth is enough to herald a new epoch: the Anthropocene. Over the past decade, a group of scientists called the Anthropocene Working Group (AWG) has been tasked with defining this potential epoch.
In 2023, the AWG submitted a proposal to its parent body, the Subcommission on Quaternary Stratigraphy (SQS), to establish the Anthropocene as an epoch beginning in the early 1950s. Crawford Lake in Canada was proposed as the marker site, with radioactive isotopes from mid-20th-century nuclear fallout preserved in its sediment serving as distinct geological evidence to mark the new unit of time.
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The proposal faced an abrupt challenge in March when news of the SQS’s decision leaked to The New York Times, revealing that 12 SQS members had voted against it, four voted in favour and two abstained.
“We were obviously highly disappointed,” says at the University of Leicester, UK, an AWG member. “We were never formally sent a rejection statement. We only found out second-hand. Normally, you’re given an opportunity to make amendments to your submission.”
Arguments against defining the Anthropocene as an epoch include the idea that a period spanning just over 70 years doesn’t fit with units on the geologic timescale, which typically span thousands of years. Furthermore, large-scale human activities, such as the industrial revolution and agriculture, extend centuries before the proposed start of the Anthropocene.
Some scientists have proposed that the Anthropocene be considered a geological event: something that contributes to the transformation of Earth’s systems, but doesn’t constitute a new unit of geological time. “That includes all human impacts going back tens of thousands of years,” says , also at the University of Leicester, who is a member of both the AWG and SQS. “It’s a valid concept but a wholly different concept.”
Initially, the AWG signalled that it planned to appeal the decision, but it ultimately chose not to take formal action. Shortly afterwards, the AWG was formally disbanded.
Now reborn as an informal group of more than 50 scientists, including Waters and Zalasiewicz, the team’s commitment to the Anthropocene continues. The group faces two possible paths forward: resubmit a revised proposal for the Anthropocene as an epoch or focus on designating Crawford Lake as a marker for a geologic age, a smaller unit of time within the Holocene. However, it is unclear how long either approach would take.
“It’s a shame: the Anthropocene has been used in many ways by many different people,” says Zalasiewicz. “This dilutes its usefulness and makes it more confusing.”
Despite the setback, the concept remains powerful, symbolising the profound human impact on Earth’s systems. “There will likely be those who use this rejection to claim that human-induced change is a gradual, natural shift,” says Waters. “That doesn’t invalidate the term Anthropocene, nor does it change the reality of the rapid, unprecedented transformations occurring on Earth.”
