The sediments deposited in Crawford Lake, a small but deep body of water in the Canadian province of Ontario, unmistakably indicate that about seven decades ago the Earth entered a new geological page under the influence of man – the Anthropocene epoch. A team of researchers announced this on Tuesday, Reuters and CNN reported.

Members of the Anthropocene Working Group (AWG) want to present their evidence to the international scientific body responsible for naming geological eras in Earth’s history.

Scientists have conducted research at 12 locations around the world and say Crawford Lake near Toronto is the site that provides the most convincing geological markers that the Anthropocene—essentially the era of man—has arrived.

The term “anthropocene”, first proposed in 2000 to reflect how profoundly human activity has changed the world, has become a commonly used academic buzzword that unites different fields of research. But there was disagreement in the scientific community about when this supposed era began and what evidence supports it.

WHEN DID THE ANTHROPOCENE BEGIN?

“When 8 billion people are impacting the planet, there are bound to be consequences,” said Colin Waters, emeritus professor at the University of Leicester’s School of Geography, Geology and Environment and chair of the Anthropocene Working Group. “We’ve entered this new state of the Earth, and it should be defined as a new geological epoch,” Waters added.

The AWG, a group that currently consists of 35 geologists, has been working since 2009 to make the Anthropocene part of the Earth’s official timeline. The group determined in 2016 that the Anthropocene began around 1950, the beginning of an era of nuclear weapons testing, the geochemical traces of which can be found around the world. Since then, the researchers have looked at 12 sites that could provide the key evidence needed to support their proposal.

Plutonium, produced by nuclear weapons testing in the 1950s, has become a “very clear marker” of the transition to the Anthropocene and has been accompanied by increased consumption of fossil fuels and fertilizers, profound changes in land use and biodiversity loss caused by agriculture, the AWG says.

The presence of plutonium and other evidence was found in Crawford Lake sediment cores.

The Anthropocene epoch has not yet been officially recognized by a scientific body called the International Commission on Stratigraphy. The Anthropocene, if officially recognized, would follow the Holocene epoch, which began 11,700 years ago at the end of the last ice age.

“It’s clear that the biology of the planet has changed dramatically” in the past 70 years, says Waters, who believes that “we can’t go back to the Holocene now.”

GOLDEN TOP

Layers of sediment deposited under water bodies and elsewhere can record how environmental conditions have changed over time. Scientists obtained sediment core samples from Lake Crawford and samples of sediment, soil, coral and ice from 11 other sites.

Researchers say the Crawford Lake sediment showed a “golden spike” that illustrates a sudden — geologically speaking — and irreversible change in conditions on Earth. Such golden spikes, officially ending one geological chapter and opening another, will be seen in rocks, glaciers or marine sediments for millennia.

“The Crawford Lake data are representative of the changes that make the mid-20th century geologically different from what went before, and deserve what we believe to be a gold rush,” said Francine McCarthy, AWG member and professor of earth sciences. at Brock University. in Canada

Crawford Lake sediments show accelerated changes that have occurred in recent decades, including traces of ash produced by burning fossil fuels. Changes in precipitation also reflect a wide range of other anthropogenic impacts, including acid rain, global warming and biodiversity loss, the scientists said.

RADIONUCLIDES

Some suggest that the Anthropocene began during the Industrial Revolution of the 18th and 19th centuries or even earlier. But the AWG team says more profound changes did not occur until the 1950s, when rapid economic and population growth led to increased greenhouse gas emissions and radionuclides from weapons testing seeped into soil and sedimentary rocks, coral, tree rings and glaciers .

“These radionuclides, particularly plutonium, have been effectively imprinted since the early 1950s in geological materials around the world, providing a radioactive tracer that will persist for over 100,000 years,” said Andrew Cundy, AWG member and Professor of Environmental Radioactivity at the University of Southampton in Great Britain.

However, the debate continues. “I’m a little bit skeptical of this exercise because it’s like trying to put a precise date on a process that’s been going on for over 50,000 years, maybe over 100,000 years, as humans spread across the planet,” said Bill Lawrence, a biologist from James Cook University in Australia.