Anthropocene
Anthropocene is a term that has been used to refer to the period of time during which humanity has become a planetary force of change. It appears in scientific and social discourse, especially with respect to accelerating geophysical and biochemical changes that characterize the 20th and 21st centuries on Earth. Originally a proposal for a new geological epoch following the Holocene, it was rejected as such in 2024 by the International Commission on Stratigraphy and the International Union of Geological Sciences.
The term has been used in research relating to Earth's water, geology, geomorphology, landscape, limnology, hydrology, ecosystems and climate. The effects of human activities on Earth can be seen, for example, in regards to biodiversity loss, and climate change. Various start dates for the Anthropocene have been proposed, ranging from the beginning of the Neolithic Revolution, to as recently as the 1960s. The biologist Eugene F. Stoermer is credited with first coining and using the term anthropocene informally in the 1980s; Paul J. Crutzen re-invented and popularized the term.
The Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy of the ICS voted in 2016 to proceed towards a formal golden spike proposal to define an Anthropocene epoch in the geologic time scale. Later that year, the group presented the proposal to the International Geological Congress.
In 2019, the AWG voted in favour of submitting a formal proposal to the ICS by 2021. The proposal located potential stratigraphic markers to the mid-20th century. This time period coincides with the start of the Great Acceleration, a post-World War II time period during which global population growth, economic growth, pollution and exploitation of natural resources have all increased at a dramatic rate. The Atomic Age also started around the mid-20th century, when the risks of nuclear wars, nuclear terrorism, and nuclear accidents increased.
Twelve candidate sites were selected for the GSSP; the sediments of Crawford Lake, Canada were finally proposed, in 2023, to mark the lower boundary of the Anthropocene, starting with the Crawfordian stage/age in 1950.
In 2024, after 15 years of deliberation, the Anthropocene Epoch proposal of the AWG was voted down by a wide margin by the SQS, owing largely to its shallow sedimentary record and extremely recent proposed start date. The ICS and the IUGS later formally confirmed, by a near unanimous vote, the rejection of the AWG's Anthropocene Epoch proposal for inclusion in the Geologic Time Scale. The IUGS statement on the rejection concluded: "Despite its rejection as a formal unit of the Geologic Time Scale, Anthropocene will nevertheless continue to be used not only by Earth and environmental scientists, but also by social scientists, politicians and economists, as well as by the public at large. It will remain an invaluable descriptor of human impact on the Earth system."
Development of the concept
As early as 1873, the Italian geologist Antonio Stoppani acknowledged the increasing power and effect of humanity on the Earth's systems and referred to an 'anthropozoic era'. From 1877 onward, the term 'Psychozoic' was used by geologists such as Joseph LeConte and Johannes Herman Frederik Umbgrove.File:The Anthropocene triple threat—climate change, biodiversity loss, and global food insecurity - Fsufs-05-564900-g001.jpg|thumb|upright=1.1|The Anthropocene is characterized by human impacts on their environment, with ramifications for variables such as climate change, biodiversity loss, and global food insecurity.An early concept for the Anthropocene was the Noosphere by Vladimir Vernadsky, who in 1938 wrote of "scientific thought as a geological force". Scientists in the Soviet Union appear to have used the term Anthropocene as early as the 1960s to refer to the Quaternary, the most recent geological period.
Ecologist Eugene F. Stoermer subsequently used Anthropocene with a different sense in the 1980s and the term was widely popularised in 2000 by atmospheric chemist Paul J. Crutzen, who regarded the influence of human behavior on Earth's atmosphere in recent centuries as so significant as to constitute a new geological epoch.
The term Anthropocene is informally used in scientific contexts. The Geological Society of America entitled its 2011 annual meeting: Archean to Anthropocene: The past is the key to the future. The new epoch has no agreed start-date, but one proposal, based on atmospheric evidence, is to fix the start with the Industrial Revolution 1780, with the invention of the steam engine. Other scientists link the new term to earlier events, such as the rise of agriculture and the Neolithic Revolution.
Evidence of relative human impact – such as the growing human influence on land use, ecosystems, biodiversity, and species extinction – is substantial; scientists think that human impact has significantly changed the growth of biodiversity. Those arguing for earlier dates posit that the proposed Anthropocene may have begun as early as 14,000–15,000 years BP, based on geologic evidence; this has led other scientists to suggest that "the onset of the Anthropocene should be extended back many thousand years"; this would make the Anthropocene essentially synonymous with the current term, Holocene.
Anthropocene Working Group
In 2008, the Stratigraphy Commission of the Geological Society of London considered a proposal to make the Anthropocene a formal unit of geological epoch divisions. A majority of the commission decided the proposal had merit and should be examined further. Independent working groups of scientists from various geological societies began to determine whether the Anthropocene will be formally accepted into the Geological Time Scale.In January 2015, 26 of the 38 members of the International Anthropocene Working Group published a paper suggesting the Trinity test on 16 July 1945 as the starting point of the proposed new epoch. However, a significant minority supported one of several alternative dates. A March 2015 report suggested either 1610 or 1964 as the beginning of the Anthropocene. Other scholars pointed 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.
A January 2016 report on the climatic, biological, and geochemical signatures of human activity in sediments and ice cores suggested the era since the mid-20th century should be recognised as a geological epoch distinct from the Holocene.
The Anthropocene Working Group met in April 2016 to consolidate evidence supporting the argument for the Anthropocene as a true geologic epoch. Evidence was evaluated and the group voted to recommend Anthropocene as the new geological epoch in August 2016.
In April 2019, the Anthropocene Working Group announced that they would vote on a formal proposal to the International Commission on Stratigraphy, to continue the process started at the 2016 meeting. In May 2019, 29 members of the 34 person AWG panel voted in favour of an official proposal to be made by 2021. The AWG also voted with 29 votes in favour of a starting date in the mid 20th century. Ten candidate sites for a Global boundary Stratotype Section and Point have been identified, one of which will be chosen to be included in the final proposal. Possible markers include microplastics, heavy metals, or radioactive nuclei left by tests from thermonuclear weapons.
In November 2021, an alternative proposal that the Anthropocene is a geological event, not an epoch, was published and later expanded in 2022. This challenged the assumption underlying the case for the Anthropocene epoch – the idea that it is possible to accurately assign a precise date of start to highly diachronous processes of human-influenced Earth system change. The argument indicated that finding a single GSSP would be impractical, given human-induced changes in the Earth system occurred at different periods, in different places, and spread under different rates. Under this model, the Anthropocene would have many events marking human-induced impacts on the planet, including the mass extinction of large vertebrates, the development of early farming, land clearance in the Americas, global-scale industrial transformation during the Industrial Revolution, and the start of the Atomic Age. The authors are members of the AWG who had voted against the official proposal of a starting date in the mid-20th century, and sought to reconcile some of the previous models. They cited Crutzen's original concept, arguing that the Anthropocene is much better and more usefully conceived of as an unfolding geological event, like other major transformations in Earth's history such as the Great Oxidation Event.
In July 2023, the AWG chose Crawford Lake in Ontario, Canada as a site representing the beginning of the proposed new epoch. The sediment in that lake shows a spike in levels of plutonium from hydrogen bomb tests, a key marker the group chose to place the start of the Anthropocene in the 1950s, along with other elevated markers including carbon particles and nitrates from the burning of fossil fuels and widespread application of chemical fertilizers respectively. Had it been approved, the official declaration of the new Anthropocene epoch would have taken place in August 2024, and its first age may have been named Crawfordian after the lake.