Scientists have found the place of the beginning of a new chapter in the history of the Earth

The term “anthropocene”, first proposed in 2000 to reflect how profoundly human activity has changed the world, has become a widely used academic buzzword for various fields of research, CNN notes.

“When 8 billion people affect the planet, the consequences are inevitable,” says Colin Waters, professor emeritus in the School of Geography, Geology and the Environment at the University of Leicester and chair of the Anthropocene Working Group.

“We have moved into this new state of the Earth, and this must be defined by a new geological epoch,” added Waters.

The AWG, currently composed of 35 geologists, has been working since 2009 to include the Anthropocene in the Earth’s official chronology. In 2016, the group determined that the Anthropocene epoch began around 1950, the beginning of the era of nuclear weapons testing, the geochemical traces of which can be found all over the world. Since then, the researchers have considered 12 sites that could provide the key evidence needed to support their proposal, nine of which were up for a vote.

On Tuesday, scientists announced a geologic feature — Lake Crawford in Ontario, Canada — that, according to their research, best reflects the geological impact of the Anthropocene.

However, not everyone in the scientific world agrees that the Anthropocene is a geological reality, or that researchers have enough evidence to officially declare it a new epoch.

The geological time scale provides the official basis for our understanding of the Earth’s 4.5 billion year history. Geologists break the history of our planet into eons, eras, periods of time, epochs and epochs – while the eon is the longest period of time, and the century is the shortest.

For example, we are currently living in the era of Meghalaya, says CNN. This is part of the Holocene epoch that began at the end of the last ice age 11,700 years ago when ice caps and glaciers began to retreat. The Holocene is part of the Quaternary period, the most recent division of the Cenozoic era, which in turn is part of the Phanerozoic era, which covers the period from 539 million years ago to the present.

These geological sections are often named after the place where they were first studied. The Jurassic period is named after the fossil-rich rocks in the French Jura mountains, while the Cambrian period takes its name from the ancient Roman name for Wales.

Andrew Knoll, Fisher Professor of Natural History at Harvard University, says the scale is “very useful” for his work as a paleontologist.

“When I say Cambrian, it means not only the time between 539 and 485 million years ago, but also an abundance of information about biota, the environment, tectonics, paleogeography and much more,” explains Professor Knoll. as they say about the Middle Ages or the Renaissance.

If approved, the Anthropocene would become the third epoch of the Quaternary. It would also mean that the Holocene epoch was especially short—other epochs lasted several million years.

Each subdivision on the official timeline is also represented by a single geological patch, known as the Global Boundary Stratotype Section and Point (GSSP), which best represents what is new or unique in a particular chapter of Earth’s history.

Each point is usually marked with a “golden spike”, often driven into the underlying rock layer, although the location may be a stalagmite or an ice core.

For the Anthropocene, the supposed location of the “golden spike” is sedimentary rocks from the bottom of Lake Crawford, which reveal geochemical traces of nuclear bomb tests, in particular plutonium, a radioactive element found widely around the world in coral reefs, ice cores and peat bogs.

Crawford Lake emerged victorious after the AWG voted nine candidate sites in three rounds. Other potential locations included a peat bog in Poland’s Sudetenland, Lake Searsville in California, a seabed in the Baltic Sea, a bay in Japan, a water-filled volcanic crater in China, an ice core drilled in the Antarctic Peninsula, and two coral reefs in Australia and in the Gulf of Mexico.

Waters said it was very difficult to choose between the different sites and the votes were close, but he thinks Crawford Lake won because the proposed sediment-related geochemical starting point for the Anthropocene is particularly accurate.

The lake is small, measuring 2.4 hectares, but it is exceptionally deep, almost 24 meters, and the deposits found at the bottom can be separated into annual layers for sampling for geochemical markers of human activity. This analysis allows scientists to see changes at yearly resolution, says Francine McCarthy, professor of geosciences at Brock University in Canada, who has studied the lake.

“The shape of the lake limits the mixing of the water column, so bottom water does not mix with surface water. The bottom of the lake is completely isolated from the rest of the planet, except that it gently sinks to the bottom,” she explained.

Andrew Cundy, professor and chair of environmental radiochemistry at the British University of Southampton and member of the AWG, said that “the presence of plutonium gives us a clear indicator of when humanity became such a dominant force that it was able to leave a unique global “imprint” on our planet.”

However, the choice of Lake Crawford is not the final decision on whether the Anthropocene will be recognized as the official geologic unit of time.

The AWG will submit a proposal to formalize the Anthropocene to the Subcommittee on Quaternary Stratigraphy later this summer. If the subcommittee members agree with a 60% majority, the proposal will then be submitted to the International Commission on Stratigraphy, which will also have to vote and agree with a 60% majority in order for the proposal to be submitted for ratification. Both bodies are part of the International Union of Geological Sciences, which represents more than 1 million geoscientists worldwide. The final decision is expected at the 37th International Geological Congress in Busan, South Korea, in August 2024, CNN notes.

But some experts do not believe that the Anthropocene is rising to an epoch-defining level.

Stan Finney, general secretary of the International Union of Geological Sciences and professor in the Department of Geological Sciences at California State University, Long Beach, said that the stratigraphic evidence for the Anthropocene is relatively minimal – barely a human lifespan – given an estimated starting point around 1950.

The scientist noted that the beginning of the Anthropocene could be determined in any number of ways, including the industrial revolution, which would lead to a much longer interval than currently suggested.

“There is no doubt that humans have greatly impacted the earth system, and today we are facing incredible consequences. But it was a long-term phenomenon,” he said.

He also believes that the desire to formally recognize the Anthropocene may actually be more political than dictated by the geology on the ground. The term was coined in 2000, not by a geologist, but by the late atmospheric chemist and Nobel laureate Paul Crutzen, apparently in rash remarks at a conference.

Finney believes it is more accurate to describe humanity’s profound impact on Earth as an ongoing geological event rather than as a formal epoch with a precise global start date. It’s also possible, he said, that stratigraphers might decide that the Anthropocene is not rising to the level of an epoch, but it could be the fourth epoch of the Holocene — a much less memorable Crawford epoch.

Other scientists object to the term “Anthropocene” because it implies the participation of all mankind in activities that have irrevocably changed the planet. Some researchers say that these changes are the work of a powerful and elite minority, and that this era would be more correctly called the Capitalocene.

Waters thinks the AWG has a strong case for formalizing the Anthropocene, but he said that naming a new geological epoch “is a very conservative process,” so there’s no guarantee the proposal will succeed.

Andrew Matthews, professor of anthropology at the University of California, Santa Cruz, said the term “anthropocene” has already shown its importance by opening up a debate between the natural, social and human sciences. Thus, the precise geological origin of the supposed epoch may not, in the end, matter all that much.

“It is firmly established that human societies have a geological effect on the world and on earth systems. And that part is useful, he said. “It basically says, ‘Look, we’re in business. We’ve changed the world and we need to keep thinking about it.’