Why everyone’s talking about the Age of Man

A panel of scientists has validated a new geological era called the Anthropocene, meaning “Age of Man”.

After spending a decade gathering evidence, the Anthropocene Working Group, chaired by Professor Jan Zalasiewicz of Leicester University, concluded that the term was suitable to express the profound impact that humans are having on the planet.

If they can persuade the International Commission on Stratigraphy (ICS) to approve the new name, “the result would be literally epoch-changing”, says The Guardian, which notes that “a new chapter of Earth’s history would need to be written”.

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What happened?

The term “Anthropocene” was first coined by Nobel Prize-winning chemist Paul Crutzen in 2000. It combines “anthropos”, the Greek for human, and “cene”, the suffix used in names of geological epochs, to suggest that Earth’s geological record has been transformed by humanity.

Crutzen argued we were no longer in the Holocene epoch, which began between 12,000 and 11,500 years ago at the close of the Paleolithic Ice Age, but rather in this new Age of Man.

In 2008, Zalasiewicz - a geologist specialising in stratigraphy, the study of rock layers and layering - was asked to assemble a team of experts to gather evidence to determine if this theory was correct.

This month, Zalasiewicz’s team announced that they were in agreement with Crutzen, and that they had defined a more specific date when humans began leaving their permanent mark on the planet - the 1950s.

And the response?

“The name has been the subject of intense debate among experts,” says Newsweek.

Some stratigraphers have argued that the term is more about politics and pop culture than hard science.

Others point to the relatively short amount of time that humans have been on Earth. Stanley Finney, secretary-general of the International Union of Geological Sciences, believes a “negligible amount of ‘stratigraphic content’ has amassed since the 1950s”, says The Guardian.

“Geologists are used to working with strata several inches deep, and Finney thought it was excessively speculative to presume that humans’ impact will one day be legible in rock,” the newspaper reports.

But Zalasiewicz insists it will, telling Nature.com: “The Anthropocene works as a geological unit of time, process and strata. It is distinguishable. It is distinctive.”

What next?

The Anthropocene Working Group will submit a proposal to the ICS by 2021 in a bid to get the term formally approved.

The commission oversees the International Chronostratigraphic Chart, a timescale of the planet’s 4.6 billion-year history, divided into phases, such as the Jurassic period. “Modifying it is a slow and tortuous process,” says The Guardian.

First, Zalasiewicz must pinpoint the “golden spike”, an exact time and location that best marks the start of the phase.

This “may encompass the hydrogen bomb tests of the 1950s, a spike in the burning of fossil fuels, or the emergence of widespread poultry farming”, says Earth.com. And it must be “measurable in the geological record in rocks, lake sediments, ice cores, or other formations in order to qualify as the sign of a new epoch”, adds the science news site.

Zalasiewicz has admitted previously that there are lots of options. “We are spoiled for choice,” he told Paris-based news agency AFP in 2016. “There’s a whole array of potential signals out there.”