Prof Colin Waters, AWG chair from the University of Leicester, said: “The Anthropocene that starts in the 1950s represents a very rapid change that we have caused to the planet. He also questioned whether an Anthropocene epoch is needed, saying: “We are but a ripple in the river of gene flow through time.” The AWG will present a dossier of evidence hoping to convince the voting bodies that the Anthropocene does represent a planetary change that requires a new geological time period.ĭr Alexander Farnsworth, at the University of Bristol, said plutonium is a radioactive element and decays over time, so might not persist over geological timescales of millions. The decision may be a difficult one for geologists, who are used to dealing with time periods spanning millions of years and using rocks with fossils as markers. Official ratification of the Crawford Lake site and the Anthropocene epoch requires passing three more votes of geological authorities, the subcommission on Quaternary Stratigraphy, the International Commission on Stratigraphy and finally the International Union of Geological Sciences.

“We are looking at something that is shaping our fate as humanity, so it’s very important to have a common reference point.”

“It also creates a bridge between the natural sciences and the humanities, because it’s about the humans,” Renn said. Prof Jürgen Renn, director of the Max Planck Institute for the History of Science, in Berlin, Germany, said: “The Anthropocene concept has now received a firm anchoring in a very precise stratigraphic definition, a reference point for scientific discussions. But it is the increase in plutonium 239 fallout specifically that we chose as the marker,” said McCarthy. “It is the great acceleration that we decided to use as a major tipping point in Earth history. The 1950s saw the start of the “great acceleration”, the unprecedented increase in industrial, transport and economic activity that occurred after the second world war and continues today. “We have a dramatic increase in the concentration in our core at exactly the same depth that we see the rapid rise in plutonium,” said McCarthy. There are other important markers in the lake sediments, including spherical carbon particles produced by the burning of fossil fuels in power plants and nitrates from the mass application of chemical fertilisers. “The presence of plutonium gives us a stark indicator of when humanity became such a dominant force that it could leave a unique global ‘fingerprint’ on our planet,” said Prof Andrew Cundy, an environmental radiochemist at the University of Southampton, and AWG member. The AWG has chosen the plutonium isotopes from H-bomb tests as the key marker for the Anthropocene, as they were spread globally from 1952 but declined rapidly after the Nuclear Test Ban Treaty in the mid-1960s, creating a spike in sediments. “The bottom of the lake is completely isolated from the rest of the planet, except for what gently sinks to the bottom and accumulates in sediment,” McCarthy said. That tall shape means the bottom waters and surface waters do not mix, which would confuse the record laid down in the sediments. The lake, formed in a limestone sinkhole, is 24 metres deep but only 2.4 hectares in area. The AWG then assessed in detail a dozen sites across the world as candidates for what geologists call a “golden spike”, ie the place where the abrupt and global changes marking the start of the new age is best recorded in geological strata.Ĭrawford Lake in Canada has been chosen to represent the start of the Anthropocene epoch on Earth The Anthropocene Working Group was set up in 2009 and in 2016 concluded that the human-caused changes to Earth were so great that a new geological time unit was justified. The climate crisis is the most prominent impact of the Anthropocene, but huge losses of wildlife, the spread of invasive species, and the widespread pollution of the planet with plastics and nitrates are also key features. If the site is approved by the scientists who oversee the geological timescale, the official declaration of the Anthropocene as a new geological epoch will come in August 2024.Įxperts said the decision has social and political importance, as well as great scientific value, as it would testify to the “scale and severity of the planetary transformation processes unleashed by industrialised humanity”.

Golden spike definition