Scientists won't classify anthropocene as 'epoch' yet — but say human impact undeniable

The idea underpinning scientists' push to recognize the current time period as a new geological epoch called the Anthropocene dates back more than 100 years, but on Tuesday, a committee of experts voted down the proposal to officially declare a new age defined by human beings' impact on the Earth.

The panel, organized by the International Union of Geological Sciences (IUGS), was tasked with weighing whether the Holocene—the epoch that began at the close of the last ice age, more than 11,000 years ago—has ended, and if so, when precisely the Anthropocene began.

Another group, the Anthropocene Working Group (AWG), had previously posed that an Anthropocene—an epoch during which "the scale and character of human activities have become so great as to compete with natural geological and geophysical forces," as British geologist Robert Lionel Sherlock argued in 1922—began in the mid-20th century.

Around that period, the U.S. and other countries began testing nuclear weapons while fossil fuel production began ramping up significantly, intensifying planetary heating, ocean acidification, and other climate impacts.

AWG presented geological evidence compiled at Crawford Lake in Canada, where radioactive isotopes dating back to the 1950s are embedded in the lake bed, to argue in favor of an Anthropocene that began decades ago.

Several members of the IUGS committee found that the time period proposed began too recently and "failed to capture the earlier impact of humans during, say, the development of farming or the onset of the Industrial Revolution," as Yale Environment 360 noted.

AWG members Simon Turner of University College London and Colin Waters of the University of Leicester told New Scientist Tuesday that the voting result was "very disappointing given the huge contribution by AWG to develop our case."

"All these lines of evidence indicate that the Anthropocene, though currently brief, is—we emphasize—of sufficient scale and importance to be represented on the Geological Time Scale," they said.

The academics who opposed recognizing a new geological epoch in the 12-4 vote are among the scientists who "prefer to describe the Anthropocene as an 'event,' not an 'epoch,'" The New York Times reported.

Geological "events" don't appear on the official Geological Time Scale, "yet many of the planet's most significant happenings are called events, including mass extinctions, rapid expansions of biodiversity, and the filling of Earth's skies with oxygen 2.1 to 2.4 billion years ago," according to the Times.

Michael Mann, director of the Center for Science, Sustainability, and the Media at University of Pennsylvania, called the disagreement over the terminology "a tempest in a teapot" that won't stop scientists from identifying the current time period as one in which humans are significantly and negatively impacting the planet.

While the scientific community is not yet labeling the current time period as a new epoch, committee member Jan Piotrowski of Aarhus University in Denmark told the Times, "Our impact is here to stay and to be recognizable in the future in the geological record."

"There is absolutely no question about this," Piotrowski said.