WEBVTT - Are We Living in a New Epoch?

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<v Speaker 1>Welcome to brain Stuff from how Stuff Works, Hey, brain Stuff,

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<v Speaker 1>Lauren bog obam Here. Thanks to greenhouse gas emissions, the

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<v Speaker 1>percentage of carbon dioxide in our atmosphere is now equal

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<v Speaker 1>to about four hundred and twelve parts per million. That's

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<v Speaker 1>a sharp increase from what levels were even sixty years ago.

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<v Speaker 1>The World Meteorological Organization says Earth's atmosphere hasn't seen such

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<v Speaker 1>a high concentration of the gas in three to five

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<v Speaker 1>million years. Harmful emissions are just one of the environmental

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<v Speaker 1>concerns that today's leaders must confront. Trash accumulation is another.

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<v Speaker 1>Since the nineteen fifties, humans have generated about nine billion

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<v Speaker 1>tons that's eight point three metric tons of plastic and

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<v Speaker 1>dumped most of it in landfills. Plus Homo sapiens are

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<v Speaker 1>overpopulating like wild as our numbers skyrocket, loads of other

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<v Speaker 1>species find themselves on the decline. You and I are

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<v Speaker 1>now witnessing one of the biggest mass extinction events of

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<v Speaker 1>all time. Donald Prothero, a paleontologist and geologist, put it

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<v Speaker 1>this way. We are a geological force in and of ourselves.

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<v Speaker 1>Mankind's overall impact on planet Earth has been so dramatic

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<v Speaker 1>that some scientists then could change to the geologic time

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<v Speaker 1>scale is in order. According to them, we should reclassify

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<v Speaker 1>the very recent past as a new unit in time

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<v Speaker 1>defined by humanities long lasting marks on the world's climate, geology,

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<v Speaker 1>and biological makeup. This proposed unit has a name, the

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<v Speaker 1>anthropasy in epoch, meaning the age of humans. Earth is

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<v Speaker 1>about four point five four billion years old. Geologists have

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<v Speaker 1>split its history into large blocks of time called eons,

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<v Speaker 1>which are further subdivided into eras, those in turn are

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<v Speaker 1>made up of smaller units called periods. Finally, the divisions

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<v Speaker 1>within a period are known as epochs. So right now

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<v Speaker 1>we're living in the co ordinary period of the Cenozoic Era,

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<v Speaker 1>which is part of the Phanerozoic eon. But the question

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<v Speaker 1>is what's the current epoch. If you'd asked someone a

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<v Speaker 1>hundred years ago, that have said the Holocene Epoch. But

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<v Speaker 1>therein lies the debate. Earth's most recent ice age ended

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<v Speaker 1>eleven thousand seven years ago. That point in time is

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<v Speaker 1>recognized as the end of the Pleistocene epoch, which began

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<v Speaker 1>just less than two point six million years ago, and

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<v Speaker 1>the dawn of the Holocene Epoch. The dividing lines between

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<v Speaker 1>epox correspond with important moments in Earth's history, like abrupt

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<v Speaker 1>changes in the climate. Evidence for these events is typically

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<v Speaker 1>found within the layers or strata of rock on our planet.

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<v Speaker 1>Ice core samples may also contain clues. Persaro explained, nowadays,

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<v Speaker 1>epos are defined by a section of rock that has

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<v Speaker 1>distinctive boundaries at the top and bottom. He added that

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<v Speaker 1>specific epox are also sometimes characterized by the presence or

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<v Speaker 1>absence of key fossils, though note that larger changes, like

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<v Speaker 1>the mass extinction of the non avian dinosaurs, are marked

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<v Speaker 1>by changes in eras. Our Cenozoic era, for example, is

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<v Speaker 1>the age of mammals. The end of the Last Ice

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<v Speaker 1>Age marked the beginning of the Holocene and established its

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<v Speaker 1>lower boundary. It's traditionally been thought that this particular epoch

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<v Speaker 1>is still going on today, but in the year two thousand,

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<v Speaker 1>Nobel Laureate Paul Krutston helped popularize an alternative viewpoint. That year,

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<v Speaker 1>heat and biologist Eugene F. Stormer argued that recent human

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<v Speaker 1>activities had pushed the world out of the Holocene and

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<v Speaker 1>into a new epoch. Decades earlier, Stormer had coined the

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<v Speaker 1>term Anthropocene, derived from the Greek word for human, as

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<v Speaker 1>a possible name for this hypothetical new unit of geologic time,

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<v Speaker 1>It's stuck. The International Commission on Strategraphy is the body

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<v Speaker 1>that standardizes the geologic time scale. It has yet to

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<v Speaker 1>recognize the Anthropocene as an official epoch, although the topic

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<v Speaker 1>has been discussed. As of this writing, the Commission maintains

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<v Speaker 1>the Holocene is still ongoing, but maybe scientists will feel

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<v Speaker 1>differently someday. Pharos heard it argued that geologists living in

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<v Speaker 1>the far off future, perhaps even tens of millions of

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<v Speaker 1>years from now quote, could tell when humans were here

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<v Speaker 1>because we've left so many traces in the rocks. Chemical

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<v Speaker 1>traces as well as actual physical objects like trash. Seawater

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<v Speaker 1>absorbs about one fourth of our carbon dioxide emissions. This

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<v Speaker 1>has led to widespread ocean a certification which will doubt

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<v Speaker 1>us leave telltale limestones behind. Dissolved carbonates in the sediment

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<v Speaker 1>are going to be another one of our calling cards.

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<v Speaker 1>Future paleontologists may also notice the sudden disappearance of a

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<v Speaker 1>great many species from the fossil record. We would also expect,

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<v Speaker 1>as yet unborn researchers to discover the radiometric signatures of

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<v Speaker 1>nuclear weaponry all around the world. Plutonium two thirty nine,

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<v Speaker 1>which is uncommon in nature, was embedded in sediments that

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<v Speaker 1>lay exposed to the air during the nuclear tests of

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<v Speaker 1>the nineteen forties, and that brings us to a bone

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<v Speaker 1>of contention about the Anthropocene. If it really is a

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<v Speaker 1>legitimate geological epoch, what moment in history should we recognize

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<v Speaker 1>as its starting point. One argument is that the Anthropocene

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<v Speaker 1>began in the nineteen forties, when the first atomic weapon

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<v Speaker 1>detonations occurred, like the famous Trinity nuclear test of nine.

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<v Speaker 1>Another option might be to define the Anthropocene as everything

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<v Speaker 1>that's happened since the Industrial Revolution kicked off. Per thea said,

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<v Speaker 1>others have wanted to push the lower boundary date all

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<v Speaker 1>the way back to when humans really started transforming the planet,

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<v Speaker 1>at the beginning of civilization and agriculture, at least ten

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<v Speaker 1>or eleven thousand years ago. Regardless, if the geological community

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<v Speaker 1>ever officially splits up the Holocene and rebrands these past

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<v Speaker 1>few decades, century or millennia as the anthroposy, and a

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<v Speaker 1>potential benefit might be the gestures symbolic value. Kreston and

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<v Speaker 1>many others hope it would send a powerful message to

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<v Speaker 1>governments and private citizens alike. As Perso puts it, when

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<v Speaker 1>you use that term, everyone else then realizes the geologists

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<v Speaker 1>are making a statement about what we've done to the planet.

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<v Speaker 1>Today's episode was written by Mark Mancini and produced by

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<v Speaker 1>Tyler Clang for iHeart Media and How Stuff Works. If

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<v Speaker 1>this episode piqued your interest about where our world is going,

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<v Speaker 1>check out the podcast The End of the World Josh

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<v Speaker 1>Clark for more existential dread and what we can do

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<v Speaker 1>to help fix it, And of course, for more on

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<v Speaker 1>this and lots of other earth changing topics, visit our

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<v Speaker 1>home planet, how Stuff Works dot com.