Climate change gives our era its own name: Anthropocene

CATHY WURZER: With last week's heat, the impact of humans on global climate was a hot topic of conversation, no pun intended. There's a new name for this time period of climate change in Earth's history. It's called Anthropocene.

Every so often on the show we get some insight into Earth's history from Jim Cotter. He's a professor of geology at the University of Minnesota Morris. He joins us right now to talk about the era that we're in. Professor, always a pleasure. How are you?

JIM COTTER: I'm doing well, Cathy. How are you?

CATHY WURZER: I am fine. I can't believe it's the last part of July-- well, the last day of July. Wow, where did that go?

Say, it's been so hot. Let's talk a little bit here about the Anthropocene. What exactly is it?

JIM COTTER: The Anthropocene is the name of a proposed new geologic epoch of geologic time. And it would designate, beginning at 1950, a distinct geologic epoch where human beings are the significant geologic agent of that time interval.

CATHY WURZER: OK. So is this as much about-- how can I say this-- geologic time as it is human impact on the planet?

JIM COTTER: It is. And, in fact, it's part of the great debate that's going to go on for the next two years or so. When I came on about this time last year, I talked about deep time and the immense nature of geologic time. And for geologists, it helps to subdivide that huge amount of time into what's called the geologic time table. And there are different geologic units.

There are eons. There are eras. There are periods and epochs. And as it stands now, we are in the Holocene Epoch of what's called the Quaternary Period of the Cenozoic Era of the Phanerozoic Eon. And what people are talking about is ending the Holocene and beginning a new epoch called the Anthropocene.

CATHY WURZER: My mind is being blown right now.

[LAUGHTER]

JIM COTTER: Too much at once, I'm sorry.

CATHY WURZER: No, no, no, no, no. It's a lot. It's a lot. But that's OK. This is why we're talking to you. So, all right, can you then say, does it mean that the Anthropocene-- Anthropocene-- it's tough to say-- are we looking at geologic changes, as we've seen in the past?

JIM COTTER: Yes. And it comes from several perspectives. In terms of geology, the part that I'm interested in -- that's the movement of surface materials-- human beings move more surface material-- soil, rock, debris-- than any other geologic process. And, in fact, almost all geologic processes combined aren't as much as humans move on a yearly basis.

Obviously, we've also changed the chemistry of the atmosphere. And, of course, we've influenced the distribution of plants and animals on the planet. We are really an impactor of geologic time.

CATHY WURZER: Is 1950-- is that particular year important because--

JIM COTTER: It is.

CATHY WURZER: --of what occurred. OK.

JIM COTTER: Yeah, it is. So there are rules to naming geologic intervals. And one of the rules is that you have to have a very distinct marker for the changing times.

So, for example, the Cenozoic, I mentioned. The Cenozoic comes after dinosaurs. And it's marked by the geology of the impact event. It's also marked by an extinction event. The non-avian dinosaurs go extinct. And it's also marked by a change in climate.

And so the distinct markers of the Anthropocene would be the surface testing of atomic bombs. They leave nuclides behind. And, as a result, it's really easy to spot them in geologic materials.

But it also is a time that's referred to as the Great Acceleration. People start moving. Post-World War II, there's a big, big shift of people moving around. There's changes in how farming is being done and what crops are being grown. And as a result, it's very easy to recognize 1950 in the geologic record.

CATHY WURZER: Say, before you go-- about a minute left here-- why is the concept of the Anthropocene in the news right now?

CATHY WURZER: Yeah. What's happened is that a working group has identified a place called Crawford Lake, which is a very special lake in Canada that accumulates sediments on a yearly basis. And so, in the record-- and they're calling it the "golden spike." In that record, you can absolutely pick out 1950. And you can absolutely pick out change in vegetation, changes in the atmospheric chemistry.

It's just a great, great site. And so people are excited about the geology, and geologic time, and just talking about human impact in a geologic scale.

CATHY WURZER: Wow. You know, I so like talking to you. You're very interesting. Jim Cotter, thank you so much.

JIM COTTER: You're welcome, Cathy.

CATHY WURZER: Mr. Cotter is Professor of Geology at the University of Minnesota Morris.