The 'Anthropocene' is a term widely used since its coining by Paul Crutzen and Eugene Stoermer in 2000 to denote the present time interval, in which many geologically significant conditions and processes are profoundly altered by human activities. These include changes in:
The 'Anthropocene' is not a formally defined geological unit within the Geological Time Scale. A proposal to formalise the 'Anthropocene' is being developed by the SQS 'Anthropocene' Working Group for consideration by the International Commission on Stratigraphy, with a current target date of 2016. Care should be taken to distinguish the concept of an 'Anthropocene' from the previously used term Anthropogene (cf. below**).
The 'Anthropocene' is currently being considered by the SQS Working Group as a potential geological series/epoch, i.e. at the same hierarchical level as the Pleistocene and Holocene series/epochs, with the implication that it is within the Quaternary Period, but that the Holocene has terminated. It might, alternatively, also be considered at a lower (age/chron) hierarchical level; that would imply it is a subdivision of the ongoing Holocene Epoch/Series.
Broadly, to be accepted as a formal term the 'Anthropocene' needs to be (a) scientifically justified (i.e. the 'geological signal' currently being produced in strata now forming must be sufficiently large, clear and distinctive) and (b) useful as a formal term to the scientific community. In terms of (b), the currently informal term 'Anthropocene' has already proven to be very useful to the global change research community and thus will continue to be used, but it remains to be determined whether formalisation within the Geological Time Scale would make it more useful or broaden its usefulness to other scientific communities, such as the geological community.
The beginning of the 'Anthropocene' is most generally considered to be at c. 1800 CE, around the beginning of the Industrial Revolution in Europe (Crutzen's original suggestion); other potential candidates for time boundaries have been suggested, at both earlier dates (within or even before the Holocene) or later (e.g. at the start of the nuclear age). A formal 'Anthropocene' might be defined either with reference to a particular point within a stratal section, that is, a Global Stratigraphic Section and Point (GSSP), colloquially known as a 'golden spike; or, by a designated time boundary (a Global Standard Stratigraphic Age).
The 'Anthropocene' has emerged as a popular scientific term used by scientists, the scientifically engaged public and the media to designate the period of Earth's history during which humans have a decisive influence on the state, dynamics and future of the Earth system. It is widely agreed that the Earth is currently in this state.
Although the term 'Anthropocene' is a recent invention, it has precursors. The first was proposed by the Italian geologist Antonio Stoppani who recognised the effects that humans were increasingly having on Earth's systems. He proposed the term Anthropozoic era for the recent period. However, this was ignored. Other possible tentative terms include the Psychozoic, proposed by the American Joseph LeConte in 1879, and the Noosphere coined for this period in 1926 by Vladimir Vernadsky and Pierre Theillard de Chardin.
Excerpt from: Nilsson, T. 1983 The Pleistocene. Reidel, Dordrecht, p. 23-4.
Soviet scientists discarded the concept of an integrated Tertiary Period. They followed certain non-Russian writers in classifying the divisions Paleogene and Neogene as periods, which they divided into the conventional epochs. Being (as they saw it) a relic of an antiquated classification, the term Quaternary, too, had been abandoned and replaced by the designation Anthropogene (analogous to Paleogene, Neogene), though its conceptional meaning remained unaltered (cf. i.a. Gerasimov, 1979). The Quaternary or Anthropogene retained the rank of a period. Linguistically, however, the term Anthropogene seems less fortunate.
With similar motivation, Czechoslovakian geologists used the term Anthropozoikum as a synonym for Quaternary. Procedures of this kind clearly over-emphasize the significance of the changes that serve to distinguish the Quaternary.
Reference: Gerasimov, I.P. 1979 Anthropogene and its major problem. Boreas 8, 23-30.