OWARDS THE ANTHROPOCENE A NEW GEOLOGICAL ERA TRIGGED BY HUMANITY ?

Lake Crawford, near Toronto in Canada, has been recognized since Tuesday July 11 as a reference site for the beginning of the Anthropocene. This site was chosen this Tuesday evening by The Anthropocene Working Group (AWG) as the world reference for the beginning of the Anthropocene, a name proposed in 2002 by Paul Crutzen, Nobel Prize in Chemistry. This one square kilometer body of water was chosen because it concentrates many emblematic traces of human activities. For example, sediments laden with microplastics, ashes from the combustion of oil and coal, concentrations of pollen which testify to the evolution of vegetation and temperature changes, and even the fallout from explosions linked to nuclear tests.

Humans become a geological factor.

These elements are proof that a new chapter in the history of the Earth has opened. For this scientific working group, which started its work 14 years ago, and which chose this site, we have entered a new geological era , that of the anthropocene, from the Greek "anthropos" which means "human". . For the first time, a new period is created which considers human activities as a key factor which has as much importance as other extra-human parameters such as the activities of the sun. The Anthropocene is the age of the Earth in which humans became a geological factor.

For these scientists, we left the Holocene, that is to say the temperate period which started 12,000 years ago, at the end of the last glaciation and which allowed the development of the human species. Because a rupture has occurred: certain environmental and climatic balances have been broken under the influence of human activities.

Change of period, or not ? Steaming theory or not ?

For these scientists, the changes have been so rapid that they are bringing the planet into a period of unprecedented climate and environmental uncertainty. A period that deserves a new name. For Jan Zalasiewicz, chairman of the working group, it is urgent to recognize the Anthropocene. Because otherwise, we would give the impression that the conditions of the Holocene, the very ones that allowed us to flourish on Earth, are still there. However, "it is clear that this is no longer the case", he believes "Science is about establishing what is real and what is not. And the Anthropocene is very real."

But it's not won yet, because, officially, we are still in the Holocene. The International Commission on Stratigraphy, which validates geological designations, has strict rules, in particular that of identifying a primary marker that marks the change of period.

For the defenders of the Anthropocene, it could be, for example, the plutonium rejected by nuclear tests, because there is very little of it in the natural state. This would therefore start this new era around 1945 - 1950, a period which also corresponds to the acceleration of human consumption, of industrial production.

Other geologists, if they recognize that there was indeed a "break" in the last century, however, believe that all the criteria are not met to speak squarely of a "new era". Phil Gibbard, secretary of the ICS, prefers the term "geological event". "The conditions that caused the glaciations haven't changed, so we can expect the Holocene to be just another interglacial." In short, that the Holocene will end with the entry into a new ice age, similar to the one that preceded it, Man having been only a hiccup in the long history of the planet.

In 2002, Paul Crutzen, Nobel Prize in Chemistry, was the first to propose recording the end of the Holocene and the beginning of the Anthropocene.

For him, the issue was almost vital: it would make it possible to focus humanity on future challenges, to make it aware of the gravity of the situation, and to "change the paradigm in scientific thought".