Are we in the Anthropocene? Geologists could define new epoch for Earth - 0 views
-
If the nearly two dozen voting members of the Anthropocene Working Group (AWG), a committee of scientists formed by the International Commission on Stratigraphy (ICS), agree on a site, the decision could usher in the end of the roughly 12,000-year-old Holocene epoch. And it would officially acknowledge that humans have had a profound influence on Earth.
-
Scientists coined the term Anthropocene in 2000, and researchers from several fields now use it informally to refer to the current geological time interval, in which human activity is driving Earth’s conditions and processes.
-
Formalizing the Anthropocene would unite efforts to study people’s influence on Earth’s systems, in fields including climatology and geology, researchers say. Transitioning to a new epoch might also coax policymakers to take into account the impact of humans on the environment during decision-making.
- ...13 more annotations...
-
Mentioning the Jurassic period, for instance, helps scientists to picture plants and animals that were alive during that time
-
“The Anthropocene represents an umbrella for all of these different changes that humans have made to the planet,”
-
Typically, researchers will agree that a specific change in Earth’s geology must be captured in the official timeline. The ICS will then determine which set of rock layers, called strata, best illustrates that change, and it will choose which layer marks its lower boundary
-
This is called the Global Stratotype Section and Point (GSSP), and it is defined by a signal, such as the first appearance of a fossil species, trapped in the rock, mud or other material. One location is chosen to represent the boundary, and researchers mark this site physically with a golden spike, to commemorate it.
-
“It’s a label,” says Colin Waters, who chairs the AWG and is a geologist at the University of Leicester, UK. “It’s a great way of summarizing a lot of concepts into one word.”
-
But the Anthropocene has posed problems. Geologists want to capture it in the timeline, but its beginning isn’t obvious in Earth’s strata, and signs of human activity have never before been part of the defining process.
-
“We had a vague idea about what it might be, [but] we didn’t know what kind of hard evidence would go into it.”
-
Years of debate among the group’s multidisciplinary members led them to identify a host of signals — radioactive isotopes from nuclear-bomb tests, ash from fossil-fuel combustion, microplastics, pesticides — that would be trapped in the strata of an Anthropocene-defining site. These began to appear in the early 1950s, when a booming human population started consuming materials and creating new ones faster than ever.
-
Why do some geologists oppose the Anthropocene as a new epoch?“It misrepresents what we do” in the ICS, says Stanley Finney, a stratigrapher at California State University, Long Beach, and secretary-general for the International Union of Geological Sciences (IUGS). The AWG is working backwards, Finney says: normally, geologists identify strata that should enter the geological timescale before considering a golden spike; in this case, they’re seeking out the lower boundary of an undefined set of geological layers.
-
Lucy Edwards, a palaeontologist who retired in 2008 from the Florence Bascom Geoscience Center in Reston, Virginia, agrees. For her, the strata that might define the Anthropocene do not yet exist because the proposed epoch is so young. “There is no geologic record of tomorrow,”
-
Edwards, Finney and other researchers have instead proposed calling the Anthropocene a geological ‘event’, a flexible term that can stretch in time, depending on human impact. “It’s all-encompassing,” Edwards says.
-
Zalasiewicz disagrees. “The word ‘event’ has been used and stretched to mean all kinds of things,” he says. “So simply calling something an event doesn’t give it any wider meaning.”