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Scientists are a step closer to officially declaring a new geological time period that marks the start of humanity’s irreversible impact on the planet.
How to define the start of the Anthropocene epoch, which would need to be visible in layers of rock in millions of years’ time, has proved controversial.
Although humans began to have big impacts on the planet with the rise of widespread farming, and later the industrial revolution, neither happened in every part of the world at the same time.
Now an international team of experts has concluded that the Anthropocene is visible globally in the top sediment layer of the Earth’s surface, starting in the 1950s.
They say the period is marked by the appearance of plutonium, a radioactive element used in nuclear weapons, as well as other indicators of a surge in human activity, called “the great acceleration”.
Professor Colin Waters, chair of the Anthropocene Working Group (AWG), said the sudden changes are an indelible signature of human influence, a so-called “golden spike”.
He said: “The presence of the plutonium mark is a very useful tool to allow you to define that boundary.
“You [also] have all these other markers reflecting the big changes to the planet that happened in the great acceleration – increasing consumption of fossil fuels, the greater use of nitrogen fertilisers, the sort of increased trade globally that’s spreading species across the planet and homogenising the biota [plant and animal life] of the planet.
“All of these things change very rapidly at that point. That’s the critical thing about the Anthropocene.”
The scientists from the AWG have nominated Crawford Lake, near Toronto, Canada, as the official global monitoring site for the Anthropocene.
It was selected from a shortlist that included a peat bog in Poland…
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