Crawford Lake in Ontario, Canada, records accurate data about Earth’s geological history in its sediment
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Geologists have singled out a lake in Canada as the best location to mark the beginning of a new era dominated by humankind’s impact on the Earth, known as the Anthropocene.
The announcement marks a major development in a long-running effort to declare that we have entered a new geological era, though three more votes are needed before the site can be formally ratified by the International Union of Geological Sciences.
Earth’s current era, the Holocene, began when the last ice age ended about 11,700 years ago. Human civilization flourished during this time, but since the mid-20se century, our impact on the planet has increased dramatically – a shift known as the Great Acceleration. Some scientists believe this event heralds the beginning of a new era dominated by humans.
In recent years, a team of researchers called the Anthropocene Working Group (AWG) has been trying to pinpoint the place on Earth that provides the best geological evidence for the Anthropocene.
“We looked at a very diverse range of natural environmental records, from a coral reef in Australia to a peat bog in Poland,” says Simon Turner to University College London, Secretary of the AWG.
At the International Congress of Stratigraphy in Lille, France, on July 11, the group announced that Crawford Lake in Ontario, Canada, will be their chosen place.
The sediment layers at the bottom of the lake, which is in a protected area and undisturbed by the outside world, record accurate records of the time they were deposited.
“Crawford Lake has this annual chronology with a really nice record of markers that we’ve suggested are associated with the Great Acceleration,” Turner says. Sediment cores from the lake show a spike in plutonium-239, the radioactive fallout from nuclear weapons testing, dating back to the early 1950s and coinciding with the increase in human activity at the time.
Other locations being considered include Sihailongwan Lake in China and Beppu Bay in Japan. Ultimately, the approval of the area’s Indigenous community and the region’s protected status was the deciding factor for Crawford Lake, says Colin Waters at the University of Leicester, UK, who heads the AWG.
Not everyone is convinced that the Anthropocene should be defined as a geological epoch. “Humans impacted natural environments about 40,000 years ago,” says Phillip Gibbard at the University of Cambridge. Instead, Gibbard and others propose that we define the Anthropocene as an event. “It’s a broad term to say that human influences started much earlier in parts of the world than elsewhere,” he says.
Crawford Lake will be put forward in a formal proposal later this year as the reference point for the beginning of the era, dubbed a “gold peak.” Some locations marking the boundaries of geologic stages are marked with a real nail driven into a layer of bedrock.
As part of the proposal, the AWG will need to determine the exact year the Anthropocene began, likely between 1950 and 1953, says Francine McCarthy at Brock University, Canada, another member of the group.
The proposal must then be approved by three separate agencies before Crawford Lake can be declared the official site that records the beginning of the Anthropocene. The AWG hopes that a decision will be made in 2024.
“It is our hope that if the stratigraphic commission draws that line and formalizes the time in Earth’s history when the planet has been so impacted by humans, it will hopefully convey a sense of urgency for people to act now to benefit our planet.” to care.” says McCarthy.
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