Human Impact May Have Pushed Earth Into a New Geological Epoch, Say Scientists

"Getting an official designation of the Anthropocene would reflect this new reality." 

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Thousands of years from now, scientists who dig up our bones may classify our remains in a new way if the results of a momentous vote on Tuesday hold up. If they do, we’ll formally be the fossilized remains (if we’re lucky) of humans born during the Anthropocene — a brand-new geologic epoch, marked by the detritus of modern life, that may soon be recognized by geology’s formal channels to succeed the ongoing Holocene epoch.

On Tuesday, the majority of the Anthropocene Working Group (AWG), a subcommittee of 34 scientists within the International Commission on Stratigraphy, voted in favor of formally declaring the Anthropocene a new epoch.

The term “Anthropocene” is already used to describe humanity’s large impact on the environment, but it has yet to actually mark a new geological epoch, like these scientists propose. Technically, we’re still in the Holocene, which began 12,000 to 11,600 years ago, but paleobiologist and AWG head Jan Zalasiewicz, Ph.D., argues that human activity has changed the Earth so drastically that it’s time to recognize a new chapter in the planet’s geological history.

“Formally we are still in the Holocene, but in reality many important geological conditions of Earth are now outside the envelope of conditions that have characterized the great bulk of the Holocene,” he tells Inverse. “Getting an official designation of the Anthropocene would reflect this new reality - and help us analyze it more effectively.”

Is the Anthropocene Geologically Real?

Tuesday’s vote builds upon an earlier, informal vote conducted at a meeting in Cape Town in 2016 and crucially lays the groundwork for the case that the AWG will submit for review in 2021. Now, the AWG must seek approval from two larger regulatory bodies before the new epoch can formally be recognized.

If they’re successful, the primary start date for the Anthropocene will be somewhere in the middle of the 20th century.

But new geological epochs mean nothing without actual evidence of change. To impress the International Commission on Stratigraphy (ICS) and the International Union of Geological Sciences (IUGS), humanity’s impact has to be shown to be “geologically real”. Zalasiewicz isn’t worried: There’s plenty of physical evidence that humans have changed the planet’s surface in the past 100 years.

anthropocene
The impacts of thermonuclear testing that date from the mid-twentieth century could be crucial markers that define the Anthropocene 

The mid-1900s conveniently stick out, says Zalasiewicz, noting that time period is associated with “an array of geological signals.” Those include sharp increases in carbon dioxide, the spread of plastics, persistent organic pollutants or concrete, widespread species invasions and extinctions, and “perturbations to the nitrogen and phosphorus cycles.”

Evidence of these characteristics will be used to make the case for the Anthropocene, but there is one dramatic signal that may drive home the AWG’s point: artificial radionuclides. Thermonuclear bomb tests from the ‘50s onward provide a “particularly sharp and globally synchronous signal” that could be used to help define the Anthropocene as well.

“It is being looked at as a possible ‘primary marker,’” Zalasiewicz explains. “Though all of the changes will be used in characterizing and recognizing an Anthropocene unit in practice.”

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The 'golden spike' marking the Global Boundary Stratotype Section and Point (GSSP) at the base of the Ediacaran Period

Finding Proof for the Anthropocene

The major holdup for the Anthropocene is that the AWG still needs to find exemplary samples from all around the world that can show a clear transition from the Holocene into the proposed Anthropocene. This transition is sometimes called a “golden spike.” A particularly good sample, if approved, would be labeled as the Global Boundary Stratotype Section and Point (GSSP), an international reference point marked by a golden plaque.

Over the next several years, the team will search for their geological smoking gun to build the final case that the Anthropocene is here — and has been for at least 50 years. “That’s a work in progress,” Zalasiewicz adds, though his team is determined.

“It’s a long process, as we are trying to analyze and reflect multi-faceted forms of change on a large and immensely complex planet,” he says. “The Geological Time Scale is meant to provide a stable reference, so changes to it are not at all easy to make.”

Read more about the emergence of the new epoch known as the Anthropocene: