According to a study titled “The Anthropocene is functionally and stratigraphically distinct from the Holocene” and published on Science Magazine, we, humans, changed the world so much that now we can say the world entered a completely a new geological era, “Anthropocene”.
What is Anthropocene?
The term is not new. As early as the 1960s, Soviet scientists used the term to refer to the Quaternary, the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). The Quaternary follows the Neogene Period and spans from 2.588 ± 0.005 million years ago to the present.
The Quaternary Period is divided into two epochs: the Pleistocene (2.588 million years ago to 11.7 thousand years ago, the world’s recent period of repeated glaciations) and the Holocene (11.7 thousand years ago to today, began after the last major ice age).
In the 1980s, ecologist Eugene F. Stoermer and atmospheric chemist Paul Crutzen claimed that the influence of human behavior on the Earth’s atmosphere in recent centuries was so significant as to constitute a new geological epoch for its lithosphere.
In 2008 a proposal was presented to the Stratigraphy Commission of the Geological Society of London to make the Anthropocene a formal unit of geological epoch divisions. A large majority of that Stratigraphy Commission decided the proposal had merit and should be examined further. Steps are being taken by independent working groups of scientists from various geological societies to determine whether the Anthropocene will be formally accepted into the Geological Time Scale.
Archean to Anthropocene
Nevertheless, today, many scientists are using the term “Anthropocene”, and the Geological Society of America entitled its 2011 annual meeting: Archean to Anthropocene: The past is the key to the future.
There is no clear agreement between scientists when the Anthropocene started (if it did start). Some scientists propose that, based on atmospheric evidence, it may be considered to start with the Industrial Revolution (late eighteenth century).
Some scientists claim it began with species exchange between old and new worlds, following the 1492 arrival of Europeans in the Americas. Some put it even earlier, at the beginning of the rise of agriculture and the Neolithic Revolution (around 12,000 years BP-“Before Present”).
In January 2015, 26 of the 38 members of the International Anthropocene Working Group published a paper suggesting that the Trinity test (it was the code name of the first detonation of a nuclear weapon, conducted by the United States Army on July 16, 1945, as part of the Manhattan Project.) on July 16, 1945, was the starting point of the proposed new epoch.
However, a significant minority supports one of several alternative dates. In March 2015, a paper published in Nature suggested either 1610 or 1964 could be the beginning of the Anthropocene. Other scholars point to the diachronous character of the physical strata of the Anthropocene, arguing that onset and impact are spread out over time, not reducible to a single instant or date of start.
The signatures of Anthropocene
According to the study cited at the beginning of the article, the main signatures defining the new epoch are:
The massive production of plastics, concrete, and aluminum
These materials forming abundant, rapidly evolving “technofossils“, recent anthropogenic deposits contain new minerals and rock types, reflecting rapid global dissemination of novel materials including elemental aluminum, concrete, and plastics that form abundant, rapidly evolving “technofossils” and can be found in newly formed rocks with high quantities.
The fallout from nuclear explosions
Starting from the Trinity test (July 16, 1945), the amount of carbon-14 and ordinarily rare plutonium-293 began to rise. Between 1952 (the first full-scale thermonuclear test was done by the United States in 1952) and 1980, the tests of thermonuclear weapons rapidly increased that amount.
Particles from fossil fuels
With the global increase in the use of fossil fuels in around 1950, black carbon, inorganic ash spheres, and spherical carbonaceous particles also increased rapidly worldwide. The radioactive elements and these particles will be visible in sentiments and rocks millions of years from now.
The excessive rate of animal extinctions
It began in the 1500s, accelerated in the late 19th century, and now it is going downhill. It will leave its mark in the fossil records, and millions of years from now, humans (if the human race can survive, of course) will surely detect this.
It is as big as (if not bigger) the major extinction events in the prehistoric ages such as the Cretaceous-Paleogene extinction event, mass extinction of some three-quarters of plant and animal species on Earth -including all non-avian dinosaurs– that occurred over a geologically short period of time, 66 million years ago.
In addition, species assemblages have been altered worldwide by geologically unprecedented transglobal species invasions and changes associated with farming and fishing, permanently reconfiguring Earth’s biological trajectory.
Related: Is Anthropocene a joke?
Some scientists, such as Whitney Autin, a stratigrapher (a scientist who studies rocks) at the SUNY College of Brockport criticize the idea. In a paper published in 2012 (with John M. Holbrook from the Texas University), Autin suggests the Anthropocene is more about pop culture than pure science.
Autin and Holbrook wrote:
“If the prescribed conditions are met (note: please see the original paper for the prescribed conditions), then Anthropocene might be a useful time stratigraphic term. In essence, it describes the disruptions driven by human activities. However, elevating terms that may become iconic in pop culture is not in itself sufficient evidence to amend formal stratigraphic practice. Science and society have much to gain from a clear understanding of how humans drive Earth-system processes instead of conducting an esoteric debate about stratigraphic nomenclature. Let the Anthropocene retain its rightful place as a focal point in the culture wars over the recognition and interpretation of the environmental process.”
The Anthropocene Working Group plans to meet in mid-2016 to submit evidence and decide whether the Anthropocene is a true geologic epoch. The proposal is set to be reviewed by the International Commission on Stratigraphy later in 2016. Should it be approved there, the proposal to adopt the term will have to be ratified by the International Union of Geological Sciences before its formal adoption as part of the geologic time scale.
Related: Forget the Anthropocene: we’ve entered the synthetic age