A group of scientists says that human activity has fundamentally changed the Earth’s geology, atmosphere and biology.
Scientists say that human activity has fundamentally altered the Earth’s geology, atmosphere, and biology so much that it has entered a new geological era known as the Anthropocene.
On Tuesday, members of the Anthropocene Working Group (AWG) presented evidence of this shift from a lake in Ontario, Canada — evidence they believe could help date the beginning of the new human-driven era.
“It is quite clear that the scale of change has intensified incredibly and this must be a human influence,” said Colin Waters, a geologist at the University of Leicester, who chaired the US working group.
He explained that human activity “no longer only affects the globe, it actually controls it.”
Tuesday’s announcement centered on the discoveries made at Lake Crawford, which is located about 60 kilometers (37 miles) west of Toronto.
Sediments deposited at the bottom of lakes can provide scientists with a geological record of changing environmental conditions.
While the team of scientists collected core samples from 11 other sites, Lake Crawford’s exceptional depth allowed sediments to float to the bottom relatively undisturbed, creating layers that can pick up distinct environmental markers.
So scientists were able to document a “golden spike” between sediment layers: a dramatic and, at least in geological terms, an abrupt change in Earth’s conditions.
Part of this “spike” indicated the presence of plutonium in the sediments of the lake. Plutonium rarely occurs naturally, leading scientists to conclude that it came from nuclear testing in the 1950s.
It was a “clear sign” of the shift into the Anthropocene, the age of humans, said Waters, the geologist. He and other members of the Ad Hoc Working Group have proposed naming the beginning of the new era between 1950 and 1954.
If accepted, the Anthropocene — derived from “anthropo,” meaning “man” — would mark the end of the Holocene, the epoch spanning the past 11,700 years.
“It’s clear that the biology of the planet has changed abruptly,” Waters added. “We can’t go back to the Holocene state now.”
But the idea of \u200b\u200bthe Anthropocene is not yet officially recognized. First suggested about 20 years ago, Nobel Prize-winning chemist Paul Crutzen has argued that the Anthropocene has been hotly debated: Scientists have disagreed about when it might have started or even how to define it.
The ad hoc working group plans to present its evidence to the International Commission on Stratigraphy, which is charged with naming geological ages for Earth’s history. Many science committees still have to vote to recognize the Anthropocene before it can be generally accepted.
John Holdren, a former White House science adviser in the US, is among those who advocate an early start date for the Anthropocene. While not a member of the AWG, he agrees that human behavior changes Earth in unexpected ways.
“The arrogance of imagining we’re in control,” Holdren told the AP. “The truth is that our ability to change the environment has far exceeded our understanding of consequences and our ability to change course.”
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