Ellen Phiddian
An international group of geologists is on the cusp of deciding how to literally mark the times we’re living in.
In 2009, geologists formed the Anthropocene Working Group, to define our current geological epoch.
They asked are we still in the Holocene, which began around 11,000 years ago, or has human activity so dramatically changed the planet’s geology that it needs a new boundary? The term ‘anthropocene’, from Ancient Greek anthropo, meaning human, was coined by Paul Crutzen and Eugene Stoermer in 2000 to illustrate this idea.
In May 2019, the AWG agreed to listing the Anthropocene as a “formal chrono-stratigraphic unit”: that is, an official part of the geographic record. They recognised the start of the Anthropocene as the middle of the 20th Century.
Next in the working group’s line of site is a Global Boundary Stratotype Section and Point, or GSSP.
These GSSPs are markers that define the boundaries of geologic stages. They’re noted in specific locations around the world by “golden spikes”, which note which geologic era the site emerged.
Of the nearly current 80 golden spikes, just one is in the Southern Hemisphere. This golden spike, which marks the Ediacaran period, was featured in Cosmos #91 by journalist Lauren Fuge. Read the full article.
The Ediacaran period, from around 635 – 540 million years ago, is the final part of the Proterozoic eon, when multicellular life first emerged.
The AWG is currently deciding where the Anthropocene golden spike should be. The working group has narrowed down a list of nine possible locations, one of which is in Australia:
- East Gotland Basin, Baltic Sea
- Beppu Bay, Japan
- West Flower Garden Bank, US
- Flinders Reef, Australia
- Palmer Ice Sheet, Antarctica
- Crawford Lake, Canada
- Sihailongwan Maar, China
- Searsville Reservoir, US
- Śnieżka, a mountain on the Polish and Czech border
Flinders Reef, off the coast of South-East Queensland, has been proposed because corals have annual growth bands which reflect their surrounding environment. At Flinders Reef, the markers in these growth bands can be traced back to the 1700s.
West Flower Garden Bank, the other proposed reef site, has similarly traceable markers, stretching back to the 1750s.
The other proposed sites include marine sediments and lake sites, where natural and anthropogenic material has built up largely undisturbed, and ice cores from Antarctica and Śnieżka, where annual snowfalls provide records of atmospheric gases.
At least 60% of the AWG needs to agree on a location before they can decide . They’re hoping to make a decision by the end of 2022.
A comparison of each site, as well as three sites which have already been ruled out, was published in Science in mid-November by the chair and secretary of the AWG.