A scientific body has agreed that Earth has entered a new
geological epoch - and humans are responsible.
In the relatively short time we've been walking the
Earth, humans have left an undeniable impact on the planet.
Now a scientific body has unanimously agreed that our
actions have altered the Earth's natural processes enough to
usher in a new geological epoch. Ladies and gentlemen,
welcome to the Anthropocene.
The deep history of our planet is measured through
various subdivided units of time, with transitions marked by
observable changes in geology. Our current position in the
timeline is the Subatlantic age (which began 2,500 years
ago), of the Holocene epoch (beginning 11,700 years ago), of
the Quaternary period (beginning 2.8 million years ago), of
the Cenozoic era (which kicked off 66 million years ago with
the extinction of the dinosaurs).
It's our current epoch, the Holocene, that's up for
contention. The transitions between these intervals are
marked by clear changes in the Earth's stratigraphy – the
layering of rock – due to various forces. A scientific body
known as the Anthropocene Working Group (AWG) believes that
human activities have caused changes to the Earth's
geological and atmospheric processes that are serious enough
to warrant declaring the Holocene is over, and that a new
epoch has begun.
Since 2000, the term "Anthropocene" has been used
informally to describe our current time, but over the past
few years the AWG has been analyzing the case for officially
defining it within the Geological Time Scale. When the
group's 35 members voted on a few key questions, all but one
agreed that the Anthropocene is geographically real, and 30
of them voted that it should be formalized. Their findings
were presented this week at the International Geological
Congress in Cape Town, South Africa.
A few more steps still need to be taken before it all
becomes official though. First, a "golden spike" needs to be
identified as a point in time where these changes really
began to take off, along with an associated sample of rock,
where these effects are visible within the layers. That will
help determine approximately when the Anthropocene began.
Paul Crutzen, the atmospheric chemist who originally coined
the term, suggested the beginning of the Industrial
Revolution marks a likely turning point.
"The Anthropocene could be said to have started in the
late eighteenth century, when analyses of air trapped in
polar ice showed the beginning of growing global
concentrations of carbon dioxide and methane," Crutzen wrote
in a
2002 paper.
The majority of the AWG, on the other hand, agreed on
1950 as a starting date. Several clear signals from that
time should be detectable in the recent rock sediment,
including plutonium fallout from nuclear experimentation,
materials like plastic, fuel ash particles, and carbon
dioxide. All of these will leave a permanent record of our
activities in the stratigraphy of the planet for future
geologists to study.
The AWG is in the process of seeking potential sites to
pull viable samples from, which could take another two or
three years. The results of that would be used as the basis
of a formal proposal to the group's parent body, which then
passes it up the chain to other bodies before anything
actually becomes official. If it makes it through that
process, the Anthropocene might not be classified as an
epoch after all, but could slot in as a new age under the
to-be-continued Holocene.
So what does this mean for us? Not much, in practical
terms. If accepted, we'll retroactively have been living in
the Anthropocene for the past 70-odd years, but a new
geological epoch doesn't happen everyday, and it's
fascinating – plus more than a little alarming – to realize
just how much we can affect the course of our home planet's
future.
Sources:
University of Leicester,
Subcommission on Quaternary Stratigraphy