Are We Living in a New Epoch?

Some geologists say that humans have had a big enough impact on the Earth that we should declare a new epoch -- the Anthropocene. Learn why in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works, Hey, brain Stuff,
Lauren bog obam Here. Thanks to greenhouse gas emissions, the
percentage of carbon dioxide in our atmosphere is now equal
to about four hundred and twelve parts per million. That's
a sharp increase from what levels were even sixty years ago.
The World Meteorological Organization says Earth's atmosphere hasn't seen such

(00:23):
a high concentration of the gas in three to five
million years. Harmful emissions are just one of the environmental
concerns that today's leaders must confront. Trash accumulation is another.
Since the nineteen fifties, humans have generated about nine billion
tons that's eight point three metric tons of plastic and
dumped most of it in landfills. Plus Homo sapiens are
overpopulating like wild as our numbers skyrocket, loads of other

(00:47):
species find themselves on the decline. You and I are
now witnessing one of the biggest mass extinction events of
all time. Donald Prothero, a paleontologist and geologist, put it
this way. We are a geological force in and of ourselves.
Mankind's overall impact on planet Earth has been so dramatic
that some scientists then could change to the geologic time

(01:08):
scale is in order. According to them, we should reclassify
the very recent past as a new unit in time
defined by humanities long lasting marks on the world's climate, geology,
and biological makeup. This proposed unit has a name, the
anthropasy in epoch, meaning the age of humans. Earth is
about four point five four billion years old. Geologists have

(01:29):
split its history into large blocks of time called eons,
which are further subdivided into eras, those in turn are
made up of smaller units called periods. Finally, the divisions
within a period are known as epochs. So right now
we're living in the co ordinary period of the Cenozoic Era,
which is part of the Phanerozoic eon. But the question
is what's the current epoch. If you'd asked someone a

(01:51):
hundred years ago, that have said the Holocene Epoch. But
therein lies the debate. Earth's most recent ice age ended
eleven thousand seven years ago. That point in time is
recognized as the end of the Pleistocene epoch, which began
just less than two point six million years ago, and
the dawn of the Holocene Epoch. The dividing lines between
epox correspond with important moments in Earth's history, like abrupt

(02:14):
changes in the climate. Evidence for these events is typically
found within the layers or strata of rock on our planet.
Ice core samples may also contain clues. Persaro explained, nowadays,
epos are defined by a section of rock that has
distinctive boundaries at the top and bottom. He added that
specific epox are also sometimes characterized by the presence or
absence of key fossils, though note that larger changes, like

(02:37):
the mass extinction of the non avian dinosaurs, are marked
by changes in eras. Our Cenozoic era, for example, is
the age of mammals. The end of the Last Ice
Age marked the beginning of the Holocene and established its
lower boundary. It's traditionally been thought that this particular epoch
is still going on today, but in the year two thousand,
Nobel Laureate Paul Krutston helped popularize an alternative viewpoint. That year,

(03:02):
heat and biologist Eugene F. Stormer argued that recent human
activities had pushed the world out of the Holocene and
into a new epoch. Decades earlier, Stormer had coined the
term Anthropocene, derived from the Greek word for human, as
a possible name for this hypothetical new unit of geologic time,
It's stuck. The International Commission on Strategraphy is the body

(03:23):
that standardizes the geologic time scale. It has yet to
recognize the Anthropocene as an official epoch, although the topic
has been discussed. As of this writing, the Commission maintains
the Holocene is still ongoing, but maybe scientists will feel
differently someday. Pharos heard it argued that geologists living in
the far off future, perhaps even tens of millions of

(03:43):
years from now quote, could tell when humans were here
because we've left so many traces in the rocks. Chemical
traces as well as actual physical objects like trash. Seawater
absorbs about one fourth of our carbon dioxide emissions. This
has led to widespread ocean a certification which will doubt
us leave telltale limestones behind. Dissolved carbonates in the sediment

(04:03):
are going to be another one of our calling cards.
Future paleontologists may also notice the sudden disappearance of a
great many species from the fossil record. We would also expect,
as yet unborn researchers to discover the radiometric signatures of
nuclear weaponry all around the world. Plutonium two thirty nine,
which is uncommon in nature, was embedded in sediments that
lay exposed to the air during the nuclear tests of

(04:24):
the nineteen forties, and that brings us to a bone
of contention about the Anthropocene. If it really is a
legitimate geological epoch, what moment in history should we recognize
as its starting point. One argument is that the Anthropocene
began in the nineteen forties, when the first atomic weapon
detonations occurred, like the famous Trinity nuclear test of nine.

(04:45):
Another option might be to define the Anthropocene as everything
that's happened since the Industrial Revolution kicked off. Per thea said,
others have wanted to push the lower boundary date all
the way back to when humans really started transforming the planet,
at the beginning of civilization and agriculture, at least ten
or eleven thousand years ago. Regardless, if the geological community
ever officially splits up the Holocene and rebrands these past

(05:07):
few decades, century or millennia as the anthroposy, and a
potential benefit might be the gestures symbolic value. Kreston and
many others hope it would send a powerful message to
governments and private citizens alike. As Perso puts it, when
you use that term, everyone else then realizes the geologists
are making a statement about what we've done to the planet.

(05:30):
Today's episode was written by Mark Mancini and produced by
Tyler Clang for iHeart Media and How Stuff Works. If
this episode piqued your interest about where our world is going,
check out the podcast The End of the World Josh
Clark for more existential dread and what we can do
to help fix it, And of course, for more on
this and lots of other earth changing topics, visit our
home planet, how Stuff Works dot com.