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| Twelve locations around the world have been proposed as "golden spots" for the Anthropocene Era, including Beppu Bay in Japan. (Source: AFP) |
Beppu Bay - "golden spot" for a geological era
The site is among a number of so-called "golden spots" that provide evidence of a new era called the Anthropocene, as humans fundamentally change the face of the Earth.
Scientists have debated for years whether the Holocene Epoch that began 11,700 years ago has actually been replaced by a new epoch characterized by human impact on Earth.
Key to the discussions was choosing a site that clearly documented how humans have changed their environment, from contaminating the environment with radioactive plutonium through nuclear testing, to the presence of microplastics in the environment...
Twelve locations around the world have been proposed as “golden spots”, including a wetland in Poland, an Australian coral reef and Beppu Bay in Oita, southwestern Japan.
Mr. Michinobu Kuwae, Associate Professor at the Center for Marine Environmental Research (Ehime University), has been researching the Beppu Bay area for nearly a decade.
He began investigating how climate change affects fish populations, through fish scales deposited in the bay's sediments.
He recently came to consider the site a potential “golden spot,” as it contains “man-made traces, including chemicals and artificial radionuclides stacked in the bay’s sediments.”
The sediment layers allow scientists to determine “the exact timing and extent of the Anthropocene-Holocene boundary,” he told AFP .
That perfect preservation is the result of several unique features, explains Yusuke Yokoyama, a professor at the Institute for Atmospheric and Oceanic Research (University of Tokyo), who analyzed core samples from the site.
The bay floor rapidly dropped away from the shore, creating a basin that trapped material in the water column and “kind of created a miso soup,” he told AFP.
“Alarm bell” for humanity
A site considered a “golden site” must meet several conditions, including providing written records going back at least a century, along with specific “man-made markers” such as nuclear bomb testing, ecosystem change and industrialization.
The site also needs to provide a complete inventory of the period and traces that allow scientists to determine which layers represent which years.
Beppu Bay's sediments contain everything from agricultural runoff to sediments from officially documented historic floods, as well as fish scales and plastic.
However, according to scientists Kuwae and Yokoyama, the most notable feature is traces from a series of nuclear bomb tests conducted across the Pacific between 1946 and 1963.
The tests produced atmospheric radiation that was detectable globally, but other signals were also found near the test sites.
“We were able to detect both,” said Yokoyama. “The reason is that Beppu Bay is downstream… from which we were able to identify specific traces of some of the tests.”
Core samples collected from Beppu Bay showed increases in plutonium associated with individual nuclear tests, and it matched similar results seen in corals in the nearby Ishigaki area.
Regardless of which site is chosen as the “golden spot,” Beppu Bay and other sites are expected to continue to be important resources for understanding human impact on the Earth.
And Mr Kuwae hopes the official designation of the Anthropocene will serve as a “wake-up call” for humanity.
“Global environmental degradation, including global warming, is accelerating,” he said.
We would be in a situation where once the original Earth is gone, there would be no way to restore it to its previous safe state.”
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