The term “Anthropocene Epoch” refers to a proposed new geological time interval. It signifies a period in Earth’s history where human activities have become the primary influence on the planet’s geology and ecosystems. This concept suggests that human actions are now comparable to natural geological forces in their ability to shape the Earth.
Understanding the Anthropocene Concept
A geological epoch is a subdivision of geological time, lasting millions of years, characterized by significant shifts in Earth’s climate, geology, and biological conditions. Epochs are part of a hierarchical structure of time that includes eons, eras, and periods. The Anthropocene is proposed to follow the Holocene Epoch, which began approximately 11,700 years ago after the last major ice age and continues to the present.
The Anthropocene concept suggests a departure from the relatively stable climatic conditions of the Holocene. Human actions are leaving a distinct and lasting mark on the planet, with their scale becoming substantial enough to potentially appear in future rock strata, indicating a fundamental shift in Earth’s system.
Human-Driven Planetary Changes
Industrialization and the extensive use of fossil fuels drive the Anthropocene. The burning of coal, oil, and natural gas releases greenhouse gases, such as carbon dioxide, into the atmosphere, leading to global warming. Since the Industrial Revolution, atmospheric carbon dioxide levels have risen from less than 280 parts per million to over 420 parts per million.
Agricultural practices and widespread land-use changes also contribute to planetary changes. Deforestation, urbanization, and habitat destruction modify Earth’s surface and disrupt ecosystems. The growing human population demands increased use of natural resources, often exceeding Earth’s capacity to regenerate them.
Pollution, including plastics and persistent organic pollutants, impacts Earth’s systems. Plastics, in particular, are now widely dispersed in sediments across terrestrial and marine environments. Human activities have also altered global biogeochemical cycles, such as the nitrogen and phosphorus cycles, largely due to the industrial production of fertilizers.
Resource extraction, through activities like mining and concrete production, reshapes the planet. The volume of concrete produced and incorporated into human constructions forms a distinct geological signature. These collective human actions have led to changes in the water cycle, imbalances in marine and terrestrial ecosystems, and an increase in extreme weather phenomena.
Evidence in Earth’s Systems
Scientists look for stratigraphic markers to identify the Anthropocene in geological records. These markers are distinct layers or features within rock strata that serve as a “fingerprint” of human activity. Such markers include novel materials, like plastics, which are now ubiquitous in sedimentary deposits and have long-term preservation potential when buried.
Concrete and aluminum are also considered new materials that can be preserved in geological layers. Radionuclides, traces of plutonium from nuclear bomb tests conducted between 1943 and 1963, serve as a globally synchronous marker. This “bomb pulse” is a strong candidate for a “golden spike,” a specific point in the geological record marking a boundary.
Evidence for the Anthropocene includes:
Changes in sediment composition, reflecting altered erosion patterns and the movement of earth material due to human activities.
Microscopic carbon residues, such as fly ash from fossil fuel combustion, found in sediment deposits with increased accumulation rates globally since the mid-20th century.
Fossil evidence, including the widespread dispersal of domesticated species and accelerated rates of species extinction, indicating human impact on biodiversity.
Chemical signatures, such as altered carbon dioxide levels in ice cores and disruptions to the nitrogen cycle, highlighting human-induced changes in Earth’s systems.
The Formal Recognition Discussion
The term “Anthropocene” is widely used in scientific and public discourse, but it is not yet an officially recognized geological epoch by the International Commission on Stratigraphy (ICS). The ICS, along with the International Union of Geological Sciences (IUGS), is responsible for formally defining geological time units.
The Anthropocene Working Group (AWG), established by the ICS in 2009, has been investigating evidence to support its formal adoption. A point of contention is the proposed start date for the epoch. While some suggest the Industrial Revolution in the mid-18th century as a starting point, others argue for the mid-20th century, coinciding with the “Great Acceleration” of human population growth and industrial production. The AWG proposed 1950 as the start date, marked by an upturn in plutonium levels globally.
Another aspect of the debate involves identifying a Global Stratotype Section and Point (GSSP), often called a “golden spike,” which is a physical marker in a geological section that defines the lower boundary of an epoch. The AWG proposed Crawford Lake in Ontario, Canada, as the GSSP, due to its distinct annual sediment layers showing traces of plutonium. However, in March 2024, the Subcommission on Quaternary Stratigraphy (SQS) voted against the formal proposal, and this decision was approved by the ICS and ratified by the IUGS. Despite this rejection, the term continues to be used by scientists and the public to describe the period of human impact on Earth.