Ecologists Butt Out: You Are Not Entitled to Redefine the Anthropocene

Why is it that some of those who publish scientific papers about “the Anthropocene” have such a profoundly mistaken understanding of what the concept means? And why do referees and journal editors let the papers through?

I was exasperated by this again on reading another paper on the starting date controversy, this one titled “The Onset of the Anthropocene”, published in the journal that carries the name of the proposed new division in the geological time scale.

In fact, I didn’t need to read past the first sentence of the abstract to know that the authors had completely misconstrued the Anthropocene, and that their conclusions would therefore be wrong. The sentence is:

“A number of different starting dates for the Anthropocene epoch have been proposed, reflecting different disciplinary perspectives and criteria regarding when human societies first began to play a significant role in shaping the earth’s ecosystems.”

It’s the very last letter that gives it away. No, the Anthropocene does not begin when humans first play “a significant role in shaping the earth’s ecosystems”; it begins when humans first play “a significant role in shaping the Earth”. That is, the Earth that evolves as a totality, as a unified, complex system comprised of the tightly linked atmosphere, hydrosphere, geosphere and biosphere. It is not about ecosystems; the belief that it is reflects the failure of ecologists (and those who think ecologically) to make the cognitive leap to thinking the Earth system, to thinking as an Earth system scientist thinks.

To say it again, because most people hear it without listening to it: ecological thinking—the science of the relationship between organisms and their local environments—is not the same as Earth system thinking—the science of the whole Earth as a complex system beyond the sum of its parts. When Earth system scientists use the deceptively ordinary term “global change”, they are in fact referring to a radically new way of thinking about the Earth.

The Earth of which Earth system scientists speak is not an aggregation of ecosystems. In their seminal article, Crutzen and Stoemer proposed that the new epoch they were naming began at the end of the 18th century because – and note the words carefully – “during the past two centuries, the global effects of human activities have become clearly noticeable”. The impact of humans on the globe became detectable from that time.

So writing about changes in landscapes, forest clearing, extinction of megafauna, “ecosystem engineering” and so on, as many participants in the debate do, is entirely irrelevant to the Anthropocene, unless it can be demonstrated that they changed the functioning of the whole Earth system in a detectable way. And they have not been able to do so.

Erle Ellis’s persistent attempts to redefine the Anthropocene as a matter of changes to the terrestrial biosphere have been particularly misleading, but one of the most misguided interventions is by an archaeologist who proposes that the Anthropocene began over 10,000 years ago when humans first began to modify land surfaces. No it didn’t; “stratigraphic evidence of direct human impact on the surface of the Earth” has absolutely no bearing on the Anthropocene, unless it can be shown that the impact was so large that it altered the functioning of the Earth system. And it didn’t.

While ecologists study the role of various species in an ecosystem, Earth system scientists study how the biota as a whole “breathes” and so helps to regulate the Earth system. While ecologists study the amount of nitrogen in the soil of an ecosystem, Earth system scientists study the way nitrogen cycles through the atmosphere, oceans, geosphere and biota. While ecologists’ records go back hundreds or at most thousands of years, Earth system scientists look back millions of years. And they worry about phenomena ecologists and archaeologists don’t even think about, like the Earth’s albedo.

When the authors of the sentence I quoted at the start write that the question is “When exactly did humans attain dominance of the earth’s environments?” they show only that they have read Crutzen, Steffen, Zalasiewicz and others through their own, distorting disciplinary lenses. When they equate “niche building” through domestication of plants with the vast and profound role humans now play in the functioning of the Earth system they wash all meaning out of Paul Crutzen’s term. When they conclude that the Anthropocene and the Holocene began at the same time, so that no new epoch is required, they are saying that what humans are doing to the Earth now is not qualitatively different to what humans did when they began to domesticate animals and cultivate crops.

This is manifestly absurd scientifically (and, it might be noted, provides political fodder for those who do not believe we face a crisis, that the arrival of the Anthropocene is no big deal). It shows that large numbers of natural scientists do not understand climate change, and do not comprehend what the IPCC is telling us.

At its core, the difference between ecological thinking versus Earth system thinking lies in divergent understandings of the object to which their thinking is applied. Ecological thinking focuses on ecosystems delimited by their spatial boundaries, and when the Earth is thought about at all it is conceived as a static ball of rock covered by overlapping ecosystems that make up a thin layer of biologically enriched fuzz.

Over the last 30 years this traditional (and in the right context useful) idea has been transcended by Earth system science with a deeper conception of the Earth as a total entity, stretching from the core of the planet to the moon and in an unceasing state of flux driven by natural cycles great and small, a flux in which humans in the Anthropocene have recently become the dominant process.

Newtonian physics applied locally is just fine, but it does not work when applied to a quantum world; in the same way, ecological thinking does not work when applied to the Earth system.

Few physicists trained in the last decades of the 19th century ever came to understand Einstein. To make the cognitive leap from ecological thinking to Earth system thinking cannot simply be learned but requires a gestalt shift, a mental reorganisation. Until that happens one cannot think correctly about the Anthropocene, and the wisest course is to butt out.


Potsdam, 11 August 2014

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© Copyright Clive Hamilton