It’s no secret that our species has had a pretty big impact on the planet. But researchers have now found definitive evidence that humans have brought about a new geological epoch, in which our actions are the primary driving force on Earth. Welcome to the Anthropocene.
Scientists have been predicting that we've been living in this new epoch for years, however, it was generally assumed that the Anthropocene started as a result of the industrial revolution in the late 1700s. But after studying the environmental impact of humans over the past 50,000 years, researchers from the University College London in the UK have now not only confirmed that the new epoch is definitely here, they've also pinpointed that it started all the way back in 1610 - most likely as a result of Europeans colonising the Americas.
"The Anthropocene probably began when species jumped continents, starting when the Old World met the New," said Simon Lewis, the lead author of the team's paper which is published today in Nature. "We humans are now a geological power in our own right - as Earth-changing as a meteorite strike."
While that may not be a great thing for the environment, there's no denying it's a pretty impressive achievement. All of the planet's previous epochs started and finished due to huge physical changes such as meteorite strikes, sustained volcanic eruptions or the shifting of the continents. A single species bringing in a new geological epoch all on its own? Well, that's a really big deal.
In order to define a new epoch, there are two main criteria that need to be met. First, there needs to be documented long-lasting changes to Earth. Second, scientists need what is called a "golden spike" - a global environmental change found in natural material such as rocks, ice, or sediment from the ocean floor, that can be dated and pinpointed to a specific year.
After scouring the geological record, the team found only two years in the past 50,000 years that fit the second criteria - 1610 and 1964, when fallout from nuclear weapon tests drastically altered the planet. But the researchers ruled out 1964 as the start of a new epoch because, so far, nuclear weapons haven't triggered long-lasting, documented changes to the planet.
So what happened in 1610 that left a mark on the planet that was more significant than nuclear fallout? The 1610 golden spike came in the form of a dramatic drop in atmospheric CO2 levels captured in the Antarctic ice-core records. The researchers believe this drop was triggered by the arrival of Europeans in the Americas in 1492 - a shift that led to the introduction of smallpox and the death of around 50 million indigenous Americans within a few decades. This put an abrupt end to farming across the continent, and also allowed the Latin American forests to regrow and start sucking up carbon again, causing CO2 levels to decline between seven and 10 parts per million.
And, unlike the nuclear weapon tests of 1964, the colonisation of the Americas also caused documented long-term changes to Earth through global trade of products such as maize and inter-continental travel.
"Many historians regard agricultural imports into Europe from the vast new lands of the Americas, alongside the availability of coal, as the two essential precursors of the Industrial Revolution, which in turn unleashed further waves of global environmental changes," said Lewis in the release. Geologically, this boundary also marks Earth's last globally synchronous cool moment before the onset of the long-term global warmth of the Anthropocene."
But although all the evidence required to announce a new epoch is there, the change isn't Facebook official as yet. Formally ratifying a new Anthropocene Epoch needs to be done by the International Union of Geological Sciences. But hopefully this new research will help them make up their mind.
"A more wide-spread recognition that human actions are driving far-reaching changes to the life-supporting infrastructure of Earth will have implications for our philosophical, social, economic and political views of our environment," said co-author of the study Mark Maslin in the release. "The first stage of solving our damaging relationship with our environment is recognising it."