Anthropocene: scientists propose this marker for the entry of the Earth into a new era

Since the XVIII^e century, scientists have set out to date the various events that have occurred during the earth’s history using a geological time scale. This great chronological system begins with the formation of the Earth and breaks down into several large geological eras (as the Paleozoicthe Mesozoic, etc.), themselves subdivided into periods/systems (Trias, Jurassic, Cretaceousetc.), eras/series then stages, in order to allow ever more precise dating.

Each compartment is therefore defined by a time interval, the beginning and the end of each era, period… being thus finely dated. Each interval has a reference stratigraphic section called the stratotype, which is characterized by several very specific paleontological, lithological or structural criteria with universal value. It is therefore natural that major mass extinctions served as a reference for dating the end of several periods.

Are we still in the Holocene?

If the geological time scale begins with the Eoarchaean, it is however open upwards. New levels, epochs or periods will therefore be added in the future to reflect the evolution of geological, environmental and biological conditions. Currently, we are in the era of Cenozoicmore precisely in the period Quaternarywhich is mainly characterized by a cycle of glaciation and through gender diversification Homo (whose appearance dates back to the end of the Pliocene). L’Holocene is the most recent era. It begins 11,700 years ago and is characterized by an interglacial period with a softening of the temperatures compared to the previous period, the Pleistocene. This favorable living environment has allowed a very stable development of the human species. But can we consider that we are still, today, in the Holocene?

the global warmingthe disappearance of many animal speciesthe modification of landscapes, pollution by synthetic chemical substances… For several decades, humanity has indeed imposed its mark and strongly impacted and modified his living environment, thus bringing about global and profound changes that surpass natural forces. For several years now, many scientists have been advancing the need to establish a new geological epoch, which would make it possible to account for the advent of the human kingdom and its impact on the Earth. This new era has a name:Anthropocenethe age of humans.

12 candidate sites to date the beginning of the Anthropocene

In the entire history of the Earth, the Anthropocene is thus the first geological period which is defined by the fact that its inhabitants have become the main driver of changes at the planetary level. If it is clear that we have entered this new period, it is still necessary to establish at what precise date to set the transition with the Holocene. Because as for the other periods and epochs, it is important to define a reference criterion but also a stratotype which will make it possible to date, almost everywhere in the world, the beginning of this new geological epoch.

Reflection groups have thus been created in order to think about this problem, which is much more complex than it seems. Twelve potential sites were proposed: the sediment of Beppu Bay in Japan, the deposits of Lake Crawford in Canada, the concretions Ernesto Cave in Italy, the corals of the Flinder Reef in Australia, the marine sediments of the Gotland Basin in the Baltic Sea, the ice cream carrots of the peninsula Antarcticmarine sediments of theestuary San Francisco in the United States, the deposits of the Searsville dam in the United States, the deposits of Lake Sihailongwan in China, the bogs of Śnieżka Bog in Poland, the urban floor of the Museum of Vienna in Austria, and the corals of the West Flower Garden Banc in the Gulf of Mexico.

Plutonium in the sediments, an indisputable marker of the human footprint

A new study has just shown that the first of these proposals, the sediments of Beppu Bay in Japan, could well represent a wise choice. Because the sediments of the ocean floor, but also the corals of this area have recorded a major change linked to human activity which could serve as a reference for dating the beginning of the Anthropocene.

From 1954, there are indeed deposits of plutonium. And this radioactive element is not natural. It is a synthetic element, produced by man and discovered for the first time in 1940 following the bombardment of a atom ofuranium 238 by deuterium. The nuclear tests which followed, from the beginning of the 1950s, therefore generated fallout of plutonium which was trapped in the marine sediments. What better marker to date the beginning of human impact on the environment and process control physical complex?

The sediments and corals of Beppu Bay could therefore be used as a reference to define the beginning of the Anthropocene. At least that’s what the authors of the study published in the journal Scientific Reports.

Beyond the scientific aspect, the definition of the Anthropocene on the same level as the other geological periods highlights light the power of the human impact on the Earth and its equivalence with the major natural processes that have governed the history of our Planet up to now. It confronts us with our responsibility and reminds us that human history is inseparable from that of the Earth.