Geologists on an international subcommittee recently rejected a proposal to formally recognize that we have entered the Anthropocene, a new geological epoch that represents the time when massive, relentless human influences began to overwhelm Earth’s regulatory systems.
A new era needs a start date. The geologists were therefore asked to vote on a proposal to mark the start of the Anthropocene using a sharp increase in plutonium traces found in sediment at the bottom of an unusually undisturbed lake in Canada, which matched many other markers of human influence .
The whole process was controversial and the two us who are on the subcommittee (Chairman Jan Zalasiewicz and Vice-Chairman Martin Head) even refused to cast a vote because we did not want to legitimize it. In any case, the proposal was opposed by long-standing members.
Why this opposition? Many geologists, who are used to working with millions of years, find it difficult to accept an era of just seventy years – that’s just one human life. Yet the evidence suggests that the Anthropocene is very real.
Environmental scientist Erle Ellis was among the critics who welcomed the decision, stating in The Conversation: “If there is one major reason why geologists rejected this proposal, it is because its recent dating and shallow depth are too limited to reveal the deeper evidence of human existence. caused planetary changes.”
It is an oft-repeated argument. But it misses the point completely. When Paul Crutzen first proposed the term Anthropocene during a moment of insight at a scientific meeting in 2000, it was not out of the realization that humans have changed the functioning and geological record of the Earth, or to put all their consequences under one umbrella. to understand the term. He and his colleagues were fully aware that people had been doing that for millennia. That’s nothing new.
Crutzen’s insight was completely different. He said that the Earth’s system – that is, the really fundamental things like the composition of the atmosphere, the climate and all ecosystems – has recently deviated sharply from the stability they had shown for thousands of years during the Holocene epoch, a stability that allowed human civilization to grow and prosper.
It makes no sense, Crutzen said, to use the Holocene for the present day. He conceived of the Anthropocene as the time when human impact suddenly and dramatically intensified enough to push the Earth into a new state. Science journalist Andrew Revkin (who coined the name “Anthrocene” before Crutzen’s inspiration) aptly called it the “great zoom.”
Meat on bones
We are part of the Anthropocene Working Group (AWG) which has collected evidence to give geological substance to Crutzen’s concept. The AWG had a mandate: to assess the Anthropocene as a potential geological time unit in which “human modification of natural systems has become predominant.” So not just any impact, but a decisive impact.
There is now no doubt about this decisive change – nor that it has left sufficient traces in recent geological strata to justify describing the Anthropocene as a unit of geological time (for such a unit must be readable in rock strata for millions of years). from now on, and not just felt as a change in circumstances). These layers are rich in fallout from nuclear bomb tests, microplastics, pesticides, fly ash, invasive species shells and much more.
Read more: Dawn of the Anthropocene: Five ways we know humans have triggered a new geological epoch
But how to show the difference between Crutzen’s idea and the “age of man” that Ellis wrote about, which he, along with others, has proposed calling an “Anthropocene event” spanning 50,000 years or more? We can use the same diagram they used:
It’s a nicely laid out, easy-to-understand image that summarizes the changes caused by human activity over the past million years. All these things certainly happened. But what is lost here is any sense of the quantified speed and magnitude of the change, apart from a bit of shading. When you look at it you wonder what all the fuss is about.
That’s because there is no Y-axis (the vertical one). It only has the X-axis, that of time. The Y-axis is what scientists use to represent the magnitude of measurements such as temperature and mass. It is absolutely crucial to gain an objective, numbers-based understanding of what is actually happening.
Now let’s see how things look when a Y-axis is added. This only shows the past 30,000 years, including the entire Holocene, but doesn’t use a logarithmic scale (that is, it doesn’t crush the big numbers) so it shows more clearly how things relate to time.
The speed and scale of the recent changes are striking. The sharp upswings are essentially Crutzen’s Anthropocene, which represents the last 72 years of what has been called the “great acceleration” of population, consumption, industrialization, technical innovation, and globalization (a more detailed way of describing the “ large zoom”).
Similar graphs can be drawn for the number of species extinctions and invasions, or for the production and distribution of fly ash, concrete, plastic, and a host of other things. They show that Crutzen’s Anthropocene is real, evidence-based, and represents (at least) change on a historical scale. The importance for all of us, of course, is that the near-vertical recent trends in these charts are still mostly upward, zooming in on a new kind of planet. The consequences cannot help but last for thousands of years – and some will change the Earth forever.
Era versus event
The Anthropocene as an epoch is thus very different from the ‘event’ of Erle Ellis and others, which includes all human influence on the planet (and is thus about a thousand times longer than the epoch, and differs in many other ways). They are both valid concepts, of course, and they overlap somewhat, just as a mouse overlaps in some respects with a blue whale (they are both mammals and share much of their genetic code). But they are different.
It is therefore absurd to give them the same name: to take Crutzen’s term and apply it to a completely different purpose, thereby obscuring the real meaning of his insight and its significance. Under another name (the Anthropolithic perhaps?) it could well complement an Anthropocene era.
Indeed, humans have had a long and complex impact on the planet. For almost all this time, they have left their mark on the earth, but they have not completely overwhelmed it. Less than a century ago, processes that began during the Industrial Revolution gained momentum. That is the Anthropocene as an era. It is real, it has already become geology and it will not go away. It is best to acknowledge it, to help us deal with its consequences.
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This article is republished from The Conversation under a Creative Commons license. Read the original article.
Simon Turner is secretary of the Anthropocene Working Group. Simon Turner received funding (2020-2023) from Haus der Kulturen der Welt (HKW, Berlin) as scientific coordinator for the programs ‘Evidence & Experiment’ and ‘Anthropocene Curriculum’ (https://www.anthropocene-curriculum.org).
Colin Waters is chairman of the Anthropocene Working Group.
Jan Zalasiewicz is affiliated with the Subcommittee on Quaternary Stratigraphy (chairman) and the Anthropocene Working Group.
Martin Head is part of the Anthropocene Working Group and the Quaternary Subcommittee.