Earlier this month, Science published a paper by the Anthropocene Working Group, or AWG, detailing the evidence of humanity’s impact on the planet. “The Anthropocene is functionally and stratigraphically distinct from the Holocene,” reads the title of their paper. Though the members agree that humanity has had a profound impact on the planet, the magnitude, timing, and significance of that impact remain up for debate. For how long have humans been altering the natural cycles of the Earth? Is our influence comparable to past geologic events? What do these inquiries tell us about our relationship with the natural world? Erle Ellis, one of the authors of the new paper and a Breakthrough Senior Fellow, brings his expertise as an ecologist and expert in cultural evolution to the working group. In the following lightly edited interview, Ellis expands on these and other questions about the Anthropocene.

How and why was the Anthropocene Working Group (AWG) assembled?

It was the vision of [University of Leicester geologist] Jan Zalasiewicz and colleagues, mostly in the UK, who decided to take on the task of defining the Anthropocene as new period of geological time. I’ve been a member since its early days though I was not one of the founding members.

Who are the AWG members? What disciplines are represented and why?*

This was initially a group of geologists and other Earth scientists. I’m an ecologist who has worked on global ecological change, and there are a number of others like me who are not geologists--an expert on the law of the sea, environmental historians, paleoecologists, a couple of archaeologists, et cetera. The original paper on the Anthropocene was by Paul Crutzen and Eugene Stoermer—an atmospheric chemist and an ecologist who didn’t really have anything to do with geologic time periods. It was Jan Zalasiewicz who brought this into geology, and he did several unusual things when he formed the group, especially by not focusing exclusively on geologists. There’s a surprising number of non-geologists in the group.

Most of us are a little unusual in our disciplines—focusing a bit more on matters at the edges of our disciplines. As for the group, I think fields like archaeology ought to be better represented because of their expertise on the long-term physical record of human culture and environmental transformation. Having a broader representation from the human side of the academy can help to open up a deeper view of what it means for humans to be seen as a global force.

What does a ‘deeper view’ provide?

The stratigraphic evidence in favor of the Anthropocene—say, beginning around 1950 [when radioisotopic evidence of atomic testing first shows up significantly in the Earth’s surface]—is really the low-hanging fruit. There are so many geologic records of what we are doing. But most of us are also interested in the deeper roots of humans as a global force, not just the peaking of our impact or the larger changes. We’re after the emergence of this force, and that’s a much more challenging thing to figure out. So this paper is an early step in the process.

So in the new paper, the AWG is choosing the evidence that will make the best case in favor of formalizing the Anthropocene?

Our goal is to develop a case, and I think we all believe there’s a case to be made. But what the best case is has not been 100% agreed upon yet.

I think it’s pretty unlikely that the Anthropocene will be formalized very soon, given the need for broader agreement on a specific “golden spike”—or physical marker—across the stratigraphic community. I don’t think there’s much controversy within the AWG about whether we’re in a new geologic time period. But that’s not true of everyone outside the group, especially in geology. Many geologists think humans are overrated in terms of our global impacts and that anyway it is too early to tell. You have to remember, humans are competing with some pretty major changes over billions of years. From that big-picture view, humanity might be seen as more a flash in the pan. While humans have had big impacts, our species has also lived through huge climate transitions, like from the Late Pleistocene to the Holocene.

In the past you’ve been a proponent of the ‘Early Anthropocene’ hypothesis — how does this effort represent that concept?

Humans have had large impacts on landscapes and probably even climate for thousands of years. There’s a new paper by Bill Ruddiman and coauthors confirming the evidence for major climate impacts from early forest clearing, rice paddies, and the like. Ecologists, anthropologists and archaeologists are used to working in the age of humans, for the most part, so there’s really no controversy within these communities about whether humans have been changing the Earth for a long time. There is some controversy about what we should do about our impacts though.

Anthropologists in particular are skeptical about drawing a line defining the Anthropocene. They think it destroys the idea that humans have had an impact for a much longer time. And they’re skeptical of a framework that might suggest a line before which humans had no impact and after which we had big impacts.

So there’s a conflict, it seems, between geologists on the one hand and archaeologists and anthropologists on the other?

Somewhat. The stratigraphers see this as a very pragmatic effort to build a dating system that stands up empirically. But they’re not trying to say that before this time there was no human influence. Even with formalization, this working group would be a long-term proposition. Boundaries get moved all the time, and a golden spike would not shut down the debate about the Anthropocene.

It sounds like different disciplines have different ways of thinking about time.

Yes. Stratigraphers have their own global system, using the Global Boundary Stratotype Section and Point (GSSP), or golden spike, and the Global Standard Stratigraphic Age (GSSA). Archaeologists have their own historical timing system—their ‘deep time’ system uses the notion of time that is relative to the site, not relative to the Earth. You can have the Paleolithic in one zone of the Earth and the Neolithic in another at the same time.

Ruddiman—who is a geologist—wrote a response piece in Science a few months ago explaining his view that stratigraphic boundaries in recent ages are not very useful to geology because the re are much better methods for looking at the timing of things like radiometric chronologies and continuous records using isotopic stages and all that. A continuous record is where the action is, he says, and in his view stratigraphy, with its discrete boundaries, is less relevant. We should look at the dynamics of the Earth, not steps or stages. There are a lot of other geologists who feel this way.

So there’s a paradox: The geologists on the AWG have clear, low-hanging-fruit evidence in favor of a formal Anthropocene, but there’s controversy within their broader community. Other disciplines like ecology and anthropology have more consensus over the processes of human impacts, but the evidence is more complicated and harder to formalize.

Yes.

Should we even be rushing to name a new epoch now? What value does a stratigraphic boundary dividing the Holocene and the Anthropocene have?

I think we ought to wait until more evidence is in and we get more consensus across disciplines, but one potential utility is that formalization establishes without a doubt in a simple way that humans have transformed the Earth and that it’s recognized by the Earth sciences. That adds some value, though it’s partly offset in that it sort of simplifies the concept of our impact to a single date. I do think the goal of seeking such a boundary should be pursued. I’m just not convinced that we’ve got the right science yet.

Why should it be pursued?

It’s taken about a quarter century, from when climate change science was first popularly discussed, for the idea to emerge from a modern Earth science point of view that humans are consequential. The consensus is not total yet—there are a lot of geologists in particular who are not convinced. But it’s underway.

This debate should gain resources across science and society. It’s not a trivial matter. John Schellnhuber—perhaps the first modern Earth scientist who tried to promote the idea that humans are a transformative global force of nature has spoken of this as a ‘second Copernican Revolution.’ For a long time, science—especially Earth sciences—has viewed humans as insignificant. Overturning that would be a big deal!

We need this kind of change in thinking. But it is daunting. People were terrified in the wake of the first Copernican Revolution, when it became clear that we’re not the center of the universe; that the Bible was wrong. But you could say that the Enlightenment came from the first Copernican Revolution. What will come from this one?

*Here’s the complete list of the members of the Anthropocene Working Group:

Tony Barnosky, University of California at Berkeley

Alejandro Cearreta, University of the Basque Country

Paul Crutzen, Max-Planck Institute for Chemistry

Matt Edgeworth, University of Leicester

Erle Ellis, University of Maryland, Baltimore County

Mike Ellis, British Geological Survey

Ian Fairchild, University of Birmingham

Agnieszka Gałuszka, Jan Kochanowski University

Philip Gibbard, University of Cambridge

Jacques Grinevald, Graduate Institute of International and Development Studies

Peter Haff, Duke University

Irka Hajdas, ETH Zurich

Alan Haywood, University of Leeds

Reinhold Leinfelder, Free University of Berlin

John McNeill, Georgetown University

Cath Neal, University of York

Eric Odada, University of Nairobi

Clément Poirier, University of Caen Normandy

Simon Price, British Geological Survey

Andrew Revkin, Pace University

Dan Richter, Duke University

Mary Scholes, University of the Witwatersrand,

Bruce Smith, Smithsonian Institute

Victoria C. Smith, Oxford University

Will Steffen, The Australian National University

Colin Summerhayes, University of Cambridge

James Syvitski, University of Colorado at Boulder

Davor Vidas, Marine Affairs and Law of the Sea Programme

Michael Wagreich, University of Vienna Althanstrasse

Colin Waters, British Geological Survey

Mark Williams, University of Leicester

Scott Wing, Museum of Natural History

Alex Wolfe, University of Alberta

Jan Zalasiewicz, University of Leicester

An Zhisheng, Chinese Academy of Sciences

The Long Anthropocene: An Interview with Erle Ellis

Jan 19, 2016