The term “Antropoceno,” or Anthropocene, describes our current time, proposing that human activity is now a primary force shaping the planet’s physical systems. This concept suggests a move away from the Holocene Epoch, the relatively stable period of the last 11,700 years. This idea frames humanity not as inhabitants, but as active geological agents altering the Earth’s fundamental operations.
The Geological Case for a New Epoch
Geologists define transitions in Earth’s history by identifying major, planet-wide changes preserved in layers of rock, ice, or sediment. These transitions are marked by a clear signal, referred to as a “golden spike” or Global Boundary Stratotype Section and Point (GSSP). This marker must be a distinct, globally identifiable layer signifying a profound shift in Earth’s systems. For the Anthropocene to be formally recognized, its beginning must be identifiable in the geological record this way.
One line of evidence comes from atmospheric changes captured in ice cores. These records show that concentrations of greenhouse gases like carbon dioxide and methane, stable for thousands of years, began to rise with industrialization. They then surged dramatically in the mid-20th century, reaching unprecedented levels and providing a global signal of altered planetary chemistry.
A distinct layer of novel materials is also becoming a permanent feature in sediments. Materials that did not exist before the 20th century, such as microscopic plastic particles, concrete, and pure aluminum, are now found globally. Scientists refer to these human-made remnants as “technofossils,” arguing they form a new, identifiable stratum that will be visible to future geologists.
The sharpest and most precisely dated signal is the presence of artificial radionuclides from nuclear weapons testing. The atmospheric detonation of atomic bombs, beginning in 1945, spread radioactive isotopes like plutonium-239 across the planet. This fallout settled and was incorporated into sediments and glacial ice, creating a globally synchronous marker in the geological record.
Pinpointing the Beginning
A central part of the scientific discussion has been determining a precise start date for this proposed epoch. One of the earlier considerations was the Industrial Revolution, which initiated the rise in atmospheric carbon dioxide. However, many scientists found this signal too gradual and not distinct enough in the geological strata to serve as a sharp boundary.
A more favored proposal centered on the mid-20th century, following the first atomic bomb detonation in 1945. The subsequent period of intense atmospheric nuclear testing distributed a clear and measurable layer of artificial radionuclides worldwide. This radioactive signature offers a sharp, globally synchronized marker that is easily detectable in sediments and ice cores, meeting the criteria for a “golden spike.”
The Great Acceleration
The concept of the Great Acceleration describes the escalation of human enterprise that began around 1950. It represents the period when the human impact on the planet’s systems went from significant to overwhelming. This was a simultaneous surge across a wide range of human activities, creating a planetary-scale shift in a short amount of time.
This surge was driven by a confluence of socio-economic factors. The primary drivers included:
- Explosive growth in the global population after World War II.
- Unprecedented economic expansion, measured by indicators like Gross Domestic Product.
- Massive increases in resource consumption, including water and energy.
- Soaring use of fertilizers for agriculture to support the growing population.
This era also saw the globalization of human systems on a new scale. International trade expanded, and transportation networks became denser and faster. These developments accelerated the movement of materials and organisms around the planet, further altering ecosystems. The Great Acceleration, therefore, represents the underlying engine of change that explains why so many geological markers became pronounced after 1950.
The Official Status and Scientific Debate
The formal process of adding a new epoch to the Geologic Time Scale involves rigorous review. The Anthropocene Working Group (AWG) was formed in 2009 to study the evidence. The AWG concluded that the Anthropocene should be a formal epoch starting in the early 1950s, selecting Crawford Lake in Canada as the site for its “golden spike.”
In March 2024, the voting members of the Subcommission on Quaternary Stratigraphy (SQS) rejected the AWG’s proposal. The decision indicated that the evidence for an epoch starting in the 1950s was not sufficient to formally end the Holocene under the strict rules for defining geological time units. This vote was later upheld by the International Union of Geological Sciences (IUGS), the ultimate authority on the Geologic Time Scale.
This rejection means the Anthropocene is not currently an official, recognized epoch in geology. The decision does not diminish the scientific evidence of profound human impact on the Earth. Many scientists who voted against the 1950s proposal argued that human influence is a long-term process that fits poorly into a single, sharply defined epoch.
Despite its formal rejection, the term “Anthropocene” remains a widely used concept across science and the humanities. It is employed to describe the current period of human-driven global change. The debate has highlighted the immense scale of humanity’s influence, even if it does not yet have a formal place on the official timeline of Earth’s history.