Welcome to the Anthropocene Epoch

Ask a geologist and you'll find out that we have been living in the Holocene Epoch. It began 12,000 years ago, a mere blink of an eye in geologic time. But scientists say humans have made such irreversible changes to the Earth that we've entered a new epoch: the Anthropocene Epoch.

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ANDREA SEABROOK, host:

Ask a geologist and you'll find out that we are living in the Holocene Epoch. It began 12,000 years ago, a mere blink of the eye in geologic time. But now, some researchers believe we've entered a new epoch of our own making. This week, on Science Out of the Box, the Anthropocene age, a time when humans are literally shaping the earth. Two geologists who think it's time we acknowledge this new reality are Jan Zalasiewicz and Mark Williams. They're researchers at the University of Leicester and authors of a new paper on the Anthropocene Epoch. They join me now.

Welcome.

Dr. JAN ZALASIEWICZ (Researcher, University of Leicester): Hello.

Dr. MARK WILLIAMS (Researcher, University of Leicester): Hello.

SEABROOK: What makes this the Anthropocene Epoch?

Dr. ZALASIEWICZ: Well, we've been living in the Holocene Epoch for about the last 11,000 years, but we think now that human modification of the planet is so great, is so enormous that perhaps we've actually entered a new epoch of time, the Anthropocene. Now that term the Anthropocene was actually coined by a Dutch atmospheric chemist Paul Crutzen about five or six years ago. And what Paul Crutzen thought was that changes to atmospheric chemistry changes in levels of CO2 in the atmosphere for example, changes in pollutants, changes in the way in which we modify the planets had actually built up to such an extent that we were now living in a completely new period of geological time. So what we have is a record of rocks with generally the oldest rocks at the bottom, and over the years, over the past 200 years or so we've divided packages of time based on rock successions. And often we can draw boundaries at major changes in the fossil record that we find in those rocks. And those big changes often reflect very fundamental changes in Earth's climate or the Earth system.

SEABROOK: Well, have things really changed that much to justify a new epoch?

Dr. WILLIAMS: Well we examined a range of different parameters, included the biology, the chemistry, and soil of the earth. And certainly if you look at, say, the amount of sediment being carried across the face of the earth, that is now much greater than in, if you like, the natural pre-Industrial past because of the amount of building we do, the amount of agriculture, and so on.

Dr. ZALASIEWICZ: Then of course changes, we've seen very significant changes in ocean chemistry as we release more carbon dioxide into the atmosphere, for example, that's interacting with the surface of the ocean, it's changing the alkalinity of that ocean, pushing it towards more acid conditions, and that's having an effect on the biota, for example, that we see in the ocean. We may see a broader fundamental change in biodiversity in the not too distant future.

Dr. WILLIAMS: Today's life is really future fossils. You know, so if, let's say coral reefs are now suffering, partly because of increased temperature, partly because of increased acidity, and if some of these coral reefs die out, then the coral reef rock, which is what we as geologists see, will stop being produced into the geological record that is forming right now.

SEABROOK: So tens of thousands of years from now, or millions of years from now, will paleontologists, if there are still paleontologists, look back and see a mass extinction at the beginning of the Anthropocene?

Dr. ZALASIEWICZ: It's possible that we will. I mean, we are entering a change of, a very rapid climate change. But when we published this article in the Geological Society of America bulletin and they asked us for a visual indication of what we thought the Anthropocene would represent and we gave them a picture of Shanghai to put on the front cover. And that's a very good representation, I think, of some of the changes that we've seen, particularly in the last 200 years on the surface of the planet.

And of course, geologists looking back from the very far future would see that record in the rock record. I mean you could say that this interval would be characterized by a huge amount of concrete around the planet, for example. So I think from a geological perspective, this Holocene to Anthropocene Epoch will leave just as distinct a record in the records as any of the previous ones going back into the deep past.

Dr. WILLIAMS: That's right. And from the far future it will be, it will be, is a biological signal in that most of the arable surface, you know, of the planet has now been transformed to feed us. So what were previously savannahs, and jungles, and forests have now been turned into vast croplands. And they leave both a signal in terms of the large-scale fossils. You replace the, you know, the animals and plants that lived there with others. And also the microfossils. All of the things that geologists study: the fossil pollen, fossil spores, those of natural forests and woodland have be replaced by those of croplands. And that's a very, it's a subtle signal, but it's one that is very widely spread across the surface of the planet.

SEABROOK: Jan Zalasiewicz and Mark Williams are from the University of Leicester. Thanks very much for speaking with me.

Dr. ZALASIEWICZ: Thank you very much.

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