Scientists are one step closer to officially declaring a new geological period that marks the beginning of humanity’s irreversible impact on the planet.
How to define the beginning of the Anthropocene era, which takes millions of years to become visible in rock layers, has proven controversial.
Although humans began to have a huge impact on the planet with the widespread rise of agriculture and later the Industrial Revolution, neither happened at the same time around the world.
Now, an international team of experts has concluded that the Anthropocene is globally visible in the top sedimentary layers of Earth’s surface, beginning in the 1950s.
This period, they say, was marked by the advent of plutonium, a radioactive element used in nuclear weapons, and other indicators of a surge in human activity known as the “Great Acceleration.”
Professor Colin Waters, chair of the Anthropocene Working Group (AWG), said sudden change was an indelible mark of human influence, the so-called “golden spike”.
Impact on industry and agriculture can be seen in sedimentary rocks from the mid-20th century
“The existence of a plutonium market is a very useful tool that allows you to define that boundary,” he said.
“you [also] All of these other markers reflect the massive changes that are taking place on the planet at great acceleration – increasing consumption of fossil fuels, greater use of nitrogen fertilizers, increased global trade are spreading species across the planet and homogenizing biota [plant and animal life] of this planet.
“By then, all of these things have changed very quickly. That’s the key thing about the Anthropocene.”
AWG scientists have designated Crawford Lake near Toronto, Canada, as the official global monitoring site for the Anthropocene.
It was selected from a shortlist that included Polish peat bogs and Australian coral reefs.
Lake Crawford, Ontario, Canada
Crawford Lake is 24m deep but has a small surface area, meaning the muddy bottom is undisturbed.
Professor Francine McCarthy, a member of the AWG who studied the lake, said: “The lake floor is completely isolated from the rest of the planet except for material that slowly sinks to the bottom and accumulates in the sediment.”
In effect, the lake floor is a time record of Earth’s environmental changes over thousands of years.
In the mid-20th century, plutonium from nuclear weapons testing in the atmosphere suddenly appeared in sediments.
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At the same time, there is evidence of microplastics, ash from coal-fired power stations, and concentrations of heavy metals such as lead.
Officially, we live in the Holocene, which began about 11,700 years ago when the climate became more stable.
The announcement of the New Anthropocene and the use of Crawford Lake as a monitoring site still need approval from three other scientific agencies recognized as the official custodians of the geological time record.
But some scientists question whether a new epoch is needed to define the “age of humanity.”
Dr Alexander Farnsworth, a geosciences researcher at the University of Bristol, said: “We are just a ripple in the genetic river flowing through time.
“Is the purpose to examine the human impact on the natural Earth system if we become extinct?
“If another advanced civilization evolved within 100 million years, could they tell that such a spike was due to a previous advanced civilization, or would they simply explain it as an interesting nature trip without any other evidence To prove our existence?”