The Anthropocene Era? Source: https://www.timetoast.com/timelines/geological-timeline-97048f3e-ae5b-46a3-8c85-6d00ad03622f
According to some scientists and newspapers, the world has entered a new geological epoch (1), supposedly characterized by the fact that humans have become the main geological force, a force that has great impact on the environmental changes we are experiencing right now, especially climate change. This epoch should be labeled “the Anthropocene”. This comes from the Greek anthropos, human being, and cainos, recent, new (the suffix “-cene” is therefore attached in geology to each geological era or epoch and specifies that it is the latest known). The tremendous impact of human activity on the biosphere would have resulted in the end of the Holocene to enter the human epoch: the Anthropocene.
This is a very controversial thesis and many scientists disagree with it. Nevertheless, we often see articles popping up on the topic, usually around the International Geological Congress that takes place every four years. So what should we think about this? I wanted to see for myself, to dig a bit deeper in the history of the concept, and to see if it is scientifically valid or useful. Let’s see!
The term was coined in 2000 by the chemist Paul Jozef Crutzen, a Nobel Prize winner. He further developed his idea in an article published in Nature in 2002. According to him the Anthropocene starts with the beginning of the thermo-industrial revolution, around 1784 (a date chosen by convention and corresponding to James Watt’s patent on the steam locomotive). According to Crutzen, the greenhouse gas emissions due to human activity led to global warming and the collapse of biodiversity. Other major changes that occurred in the biogeochemical cycles of water, azote and phosphate are also due to human influence. Although we cannot deny the tremendous and damaging impact of human activity on the planet, does that mean that we have to coin the Anthropocene as a geological epoch? Let’s see if there is any stratigraphic tangibility to the concept.
The International Geological Congress has an international commission in charge of the stratigraphy, which they measure based on stratigraphic division. Within this commission, some scientists oversee the Quaternary stratigraphy, and among them, we find a working group on the Anthropocene that was formed during the 2012 congress meeting. Their job was to find any stratigraphic evidence for the Anthropocene theory. Although they starting working on gathering evidence, no decision was made and the research was pushed to continue in 2016.
Indeed, the 35th International Geological Congress took place last summer, from August 24th to September 4th, 2016 in Cape Town, South Africa. The working group then tried to answer such questions as: Does the Anthropocene have a stratigraphic reality? Shall it be accurately defined as a stratigraphic unit or can we settle for the informal use of the term? What would the characteristic stratigraphic markers be? Which sediment should account for its basis in reality? What stratigraphic ruptures in the sedimentation can account for the Anthropocene hypothesis? Basically, they are looking for a ‘golden spike’ (Global boundary Stratotype Section and Point), which is a physical reference point in strata at one carefully selected place. The signal should occur globally and synchronically if we are to define a new geological epoch. So, what is this signal? What are we looking for in the geological record to account for the Anthropocene hypothesis?
Stratigraphy. Source: http://adventuregeology.blogspot.com/
According to the working group the top two candidates are radiocarbon and plutonium, which are both the result of nuclear test fallouts. Consequently, they place the beginning of the Anthropocene around 1950, also known as “the Great Acceleration”, a period during which the whole range of indicators of the human footprint on Earth (demography, CO2 emissions, energy consumption, biodiversity extinction, forest withdrawal, nitrogen and phosphorus cycles, etc) rose tremendously. The beginning of the Anthropocene is being associated with the beginning of planet-wide radionuclide fallout caused by thermonuclear weapons tests. So, for the working group it’s not the carbon dioxide concentration, the measure proposed by Paul Crutzen placing the beginning of the Anthropocene at the end of XVIIIth century, that must be chosen as the golden pike : depending on which marker we choose, the beginning of the Anthropocene will not be the same.
Other candidates for the golden pike have been proposed by other scientists: aluminum, plastic, fuel ash particles, methane concentration, oxygen isotope change, nitrate and phosphate concentration, acceleration in rates of erosion and sedimentation, as well as biostratigraphic evidences such as extinctions, unprecedented levels of species invasions across the Earth, a variety of fossilizable biological remains, including chicken bones fossils! The problem is that all those modifications are progressive, which make it difficult to find a synchronic criterion and to place a limit for the beginning of the Anthropocene.
There are also other candidates for the supposed beginning of the Anthropocene (besides 1784 and 1950). Some scientist place the alleged beginning of it at -7ka, during the Neolithic and the beginnings of agriculture and farming; or around 1610 when Europeans invaded America which was the beginning of globalization and capitalist economy and the mix of different species from different continents.
What we can see is that there are a lot of speculations and theories, but not many answers and scientific facts. One of the Anthropocene working group’s task is to find a reliable golden pike before the next International Geology Conference that will take place in Delhi in March 2020 (and then present it to the congress and defend their case). Even if we are facing tremendous changes due to human activity that are long-lasting, and some irreversible and that will probably leave a permanent record in the Earth’s strata, we don’t have a reliable marker to establish that we are in the Anthropocene yet.
Another critique that was made, besides the one on the marker and the difficulty to place the beginning of the Anthropocene is that this period of time is too short compared to the epochs that we are used dealing with on the Geological Time Scale, such as the Holocene for example, that began approximately 11,700 years ago. As argues Patrick De Wever, professor at the Muséum National d’Histoire Naturelle in Paris, “the Anthropocene period is defined as due to human activity, and therefore is to be placed inside the history of humankind and has a place in the calendar of human history. Why do some want to make it a geological era? This would be both useless and inappropriate because it doesn’t possess the characteristics [of a geological era or epoch]” (2).
According to De Wever, there is a small group (the Anthropocene working group) that tries to push this concept into the Geological Time Scale, but they gave only two presentations at the previous congress on the topic. According to him, the press is exalting the debate even though most geologists disagree with the concept. The work of the Anthropocene working group is far from being completed and from reaching consensus. He believes the debate around the Anthropocene is more societal than geological.
Currently, in the humanities, there is a tremendous number of publications around the concept of the Anthropocene. It has the advantage of rising ecological consciousness, by allowing us to take the full measure of the scale at which the changes in the biosphere due to human activity are occurring and its irreversibility. It helps us acknowledge our responsibility in the current state of the planet and provoke a debate. Nevertheless, even in the humanities, some academics criticize the Anthropocene concept as being a unique, unequivocal and catastrophist story, one that does not allow for much resistance, standardizes and reduces the complexities of the social and natural world we live in. Who is the anthropos in the Anthropocene? Do all humans have the same responsibility in the ecological crisis we are facing right now? Some scholars suggested terms such as “Capitalocene” that seem to better take into account the production systems that led us to the current situation. Anyway, let’s just remember that, even from the point of view of the field of the humanities, the concept is in debate.
The Anthropocene is not indisputably a geological epoch, at least for the moment now, even if it raises some interest in a broader sense when we speak about the sciences of the Earth System, beyond stratigraphy. An informal use of the term is still an option, but not with a certain recognition as an actual geological epoch, at least not yet.
This article was written by Olga Potot, a Master’s student in the Museum’s “Museology of Social and Natural Sciences” specialization.
Bibliography:
(1) And we here speak of an epoch, not an era. The theory considered here is the one according to which the Anthropocene epoch would follow the Holocene epoch, within the quaternary era.
(2) Patrick De Wever, professeur au MNHN, Le Monde, 12/09/2016
Muséum national d'histoire naturelle 