The Earth has now entered a new geologic epoch known as the Anthropocene because human activity has so fundamentally altered the geology, atmosphere, and biology of the plant, scientists say.
Members of the Anthropocene Working Group [AWG] have presented evidence of the shift from a lake in Ontario, Canada — which they think can help pinpoint a start date for the new epoch.
Scientists documented what they call a “golden spike” in the layers of the lake’s sediment, a dramatic and sudden change in the conditions of the earth.
Part of the “spike” was evidenced by plutonium in the lake sediment. Plutonium infrequently occurs naturally, leading scientists to conclude it came from nuclear testing in the 1950s.
Geologist Colin Waters, from the UK’s University of Leicester, said it was a “clear marker” for the shift to the Anthropocene, the age of humans.
The AWG has now proposed documenting the start of the new epoch as beginning between 1950 and 1954.
According to Carterton-based geologist Chris Hollis, one of the only known time stamps like the plutonium left from nuclear testing was found in the Paleocene, which he studies.
Hollis is part of the International Commission on Stratigraphy, which has sub-commissions for various “intervals in the time scale”. He’s part of the small international team that looks after the Paleogene – the time from the end of the dinosaurs 66 million years ago to the first major glaciation on Antarctica, 34 million years ago.
The AWG is another one of the sub-commissions.
Hollis said he has done similar work for the Paleocene, with an “iridium anomaly” that marks the asteroid impact and also the carbon isotope blip that marks the methane burp and global warming event at the end of the Paleocene, 56 million years ago.
Evidence of a massive tsunami following the asteroid’s impact was found at Tora in South Wairarapa and released in a report co-written by Hollis last year.
He said the AWG’s research has proven that humans have done enough to change the course of the Earth’s history.
He said to define the Anthropocene, there needed to be a “time marker” that happens precisely at the same time, everywhere on the planet.
Although both the initial impact of the nuclear bomb and the asteroid were confined to one place, the chemical traces can be found everywhere.
But what’s next? Hollis said the planet is now moving into a climate state it hasn’t seen for at least 10,000 years, and “probably more like 3 million years”.
Climate change predictions presented by Greater Wellington Regional Council, using Intergovernmental Panel on Climate Change modelling, show that under the “moderate scenario” [RCP 4.5], Masterton could expect to have 30 more “hot days” above 25 degrees Celsius per year by 2100.
Hollis said marking the Anthropocene showed that humans’ impact on the planet are not limited to climate change.
“It’s defined by a nuclear bomb. It’s a whole range of things that humans are doing to the planet – biodiversity loss, nuclear bombs, and nuclear plant explosions are all part of it.
“Climate change is just one of many things that humans are doing to make their mark on the planet.”