Anthropocene means multiple crisis of our species – 07/11/2023 – Environment

The great transitions in the geological history of our planet usually correspond to processes that, from our species’ point of view, appear to be very long-term, unfolding over hundreds of thousands of years.

There are only two clear exceptions to this rule: the fall of the celestial body that ended the reign of dinosaurs 66 million years ago; and the beginning of the Anthropocene, the epoch of humanity, in the mid-20th century.

It is true that the proposal to agree on the exact starting point of the Anthropocene (the sediments dating back to the 1950s extracted from the bottom of Lake Crawford, in Canada, as announced this Tuesday) still has a considerable way to go before it is approved by the community. scientific.

But the similarities with the effects of the bolide that hit Earth tens of millions of years ago are significant — certainly, in part, because the analogy did not escape the very geologists responsible for the idea.

In both cases, we are talking about phenomena that happened at a clearly defined moment in time and that were able to produce a “signature” of their impact on a planetary scale —a trademark that cannot be confused with that of other events.

In the case of the end of the Age of Dinosaurs, the signature in question includes a thin layer of iridium, a metal much more common in meteorites than in the Earth’s crust, which strengthens the idea that the tragedy was caused by an object that fell into our planet.

One of the markers of the beginning of the Anthropocene is the presence of radioactive isotopes (variants of chemical elements) that the Earth does not usually produce by natural means, but are the result of nuclear weapons tests in the early years of the Cold War between the USA and the Union. Soviet.

Other similarities between the two events are more insidious and troubling. On the one hand, the meteorite’s impact 66 million years ago produced a host of different effects—planetary-scale fires, a possible spur to volcanism, drastic increases in ocean acidity, and a years-long “nuclear winter.”

The outbreak of the Anthropocene, although it is much less drastic in the short term (or while no one decides to use large nuclear arsenals against an enemy), corresponds to a multiplicity of crises, even more systemic than those of the Age of Dinosaurs.

That’s why Canadian lake sediments are marked not only by the signature of nuclear tests but also by evidence of the so-called Great Acceleration — the moment when modern civilization began to consume increasingly exorbitant amounts of fossil fuels and other natural resources.

This process also produced such things as organic pollutants and particulate matter linked to combustion on an industrial scale, which in their own way are as improbable and unmistakable as the variants of the radioactive element plutonium in American and Soviet bombs.

The combination of these different signatures is the very essence of what science has come to understand as the beginning of the Anthropocene. And that is why the movement to rename the geological moment we are going through is much more than an exercise in public relations or environmentalist propaganda, as the critics of the idea would say.

Inserting the era of humanity into the textbooks of the future is a way of recognizing that we are facing a multiple crisis directly linked to the transformation of our species into a geological force — something that had not happened before to any other species of mammal, or even vertebrate. , over hundreds of millions of years of existence of both groups.

From a single profound cause —our newly acquired ability to monopolize the biosphere’s energy sources and raw materials—, the so-called planetary limits are being surpassed.

In other words, everything indicates that our capacity to consume what the Earth produces already exceeds, in almost all aspects, the capacity of the biosphere to regenerate itself. Making the Anthropocene official is one of the ways to make clear, through a single word, the magnitude and risks of this process.