The human impact on Earth’s chemistry and climate has cut short the 11,700-year-old geological epoch known as the Holocene and ushered in a new one, scientists said on Monday.
The Anthropocene, or “new age of man,” would start from the mid-20th century if their recommendation — submitted on Monday to the International Geological Congress in Cape Town, South Africa — is adopted.
That approval process is likely to take at least two years and requires ratification by three other academic bodies. But after seven years of deliberation, the 35-strong Working Group has unanimously recognised the Anthropocene as a reality, and voted 30-to-three (with two abstentions) for the transition to be officially registered. “Our working model is that the optimal boundary is the mid-20th century,” said Jan Zalasiewicz, a geologist at the University of Leicester.
“If adopted — and we’re a long way from that — the Holocene would finish and the Anthropocene would formally be held to have begun.” Scientists refer to the period starting from 1950 as the “Great Acceleration,” and a glance at graphs tracking a number of chemical and socio-economic changes make it obvious why.
Concentrations in the air of carbon dioxide, methane and stratospheric ozone; surface temperatures, ocean acidification, marine fish harvesting, and tropical forest loss; population growth, construction of large dams — all of them take off from about mid-century.
But the working group is not allowed to take any of these measures into consideration unless they show up in the geological record.
If it can’t be measured in rocks, lake sediments or ice cores, it doesn’t count. This is not a problem when it comes to the Anthropocene, said Mr. Zalasiewicz. Micro-plastics, for example — a synthetic, man-made substance — “are now components of sediment around the world, both in land and in the sea.” — © AFP, 2016
