The Anthropocene Epoch: Defining a New Geological Age

The scientific community has spent more than a decade debating a singular, massive question. Have humans altered the planet so drastically that we have ended the Holocene epoch and entered a new one? This proposed timeline is called the Anthropocene. While the term is widely used in pop culture and environmental science, the official geological ruling is far more complex and involves strict evidence found in rock, sediment, and ice.

The Recent Vote: A Geological Verdict

In March 2024, a defining moment occurred for the concept of the Anthropocene. The Subcommission on Quaternary Stratigraphy (SQS), a body within the International Union of Geological Sciences (IUGS), held a vote to decide if the Anthropocene should officially replace the Holocene on the International Chronostratigraphic Chart.

The proposal suggested that the Anthropocene began in the mid-20th century. This period is often called the “Great Acceleration,” marked by rapid industrialization, population growth, and nuclear testing.

The result: The proposal was rejected.

The committee voted 12 to 4 against the proposal (with several abstentions). This means that, officially, we are still living in the Holocene epoch. Specifically, we are in the Meghalayan Age, which began 4,200 years ago. The rejection does not deny that humans have changed the planet. Instead, the geologists argued that the timeline was too short and that human impact extends far deeper into history than just the 1950s.

The "Golden Spike" at Crawford Lake

To declare a new epoch, geologists need a Global Boundary Stratotype Section and Point (GSSP). This is often called a “Golden Spike.” It acts as the physical reference point in the geological record that shows exactly when a change occurred globally.

The Anthropocene Working Group (AWG) selected Crawford Lake in Ontario, Canada, as this primary site. Crawford Lake is unique because it is a meromictic lake. This means the water layers do not mix. Sediment sinks to the bottom and remains undisturbed, creating perfect annual layers similar to tree rings.

Researchers found distinct markers in the mud of Crawford Lake that spiked in the early 1950s:

• Plutonium-239: Radioactive isotopes from hydrogen bomb tests.
• Fly Ash: Residue from burning fossil fuels like coal at high intensity.
• Microplastics: Synthetic particles not found in nature before the 20th century.

Despite this clear evidence, the voting body determined that while these markers are real, they do not justify ending the Holocene after only 70 years.

Why Was the Proposal Rejected?

The debate over the Anthropocene highlights a clash between rigid geological standards and broader environmental reality. The geologists who voted “no” had several specific reasons for their decision.

The “Event” vs. “Epoch” Argument

Many stratigraphers believe human impact is better described as an ongoing geological “event” rather than a single epoch. Events can span millions of years and cut across different epochs. For example, the Great Oxidation Event changed Earth’s atmosphere permanently but did not fit neatly into one small time box. Viewing the Anthropocene as an event acknowledges that human agriculture began altering the landscape thousands of years ago, not just in 1952.

The Problem with 1950

Setting the start date to the 1950s ignores the massive environmental changes caused by early agriculture, the colonization of the Americas, and the early Industrial Revolution. Critics of the proposal argued that defining the Anthropocene by nuclear fallout narrows the scope of human influence too much.

Physical Evidence of Human Impact

Even though the capital-A “Anthropocene” is not yet an official epoch, the physical proof of humanity in the rock record is undeniable. Geologists refer to these man-made materials as “technofossils.” Future geologists looking at the strata of the 21st century will see a distinct layer unlike any before it.

Common markers include:

• Concrete: We have created enough concrete to coat the entire Earth in a layer two millimeters thick. It will act as a pervasive rock layer in the future.
• Aluminum: Pure metallic aluminum is rare in nature. The sheer volume of refined aluminum cans and construction materials will leave a permanent chemical signal.
• Chicken Bones: The modern broiler chicken has a skeleton distinct from its ancestors due to breeding. Billions of chicken bones in landfills create a worldwide fossil layer.
• Plastic: Plastic rocks, or “plastiglomerates,” are forming where melted plastic binds with sand and rock fragments.

The Future of the Term

The rejection of the proposal does not mean the word “Anthropocene” will disappear. It remains a vital concept in anthropology, sociology, history, and climate science. It serves as a framework for understanding how humanity has become a geological force on par with volcanoes or asteroid impacts.

Jan Zalasiewicz and Colin Waters, leaders of the Anthropocene Working Group, expressed disappointment in the March 2024 vote. However, they noted that the evidence gathered regarding Crawford Lake and other sites remains scientifically valid. The IUGS has stated that the Anthropocene will continue to be used as an informal geological term, much like the “Ice Age” is used informally to describe the Pleistocene.

Frequently Asked Questions

Is the Anthropocene officially recognized? No. As of the March 2024 vote by the International Union of Geological Sciences, the Anthropocene is not an official unit of the Geological Time Scale. We officially remain in the Holocene epoch.

Who coined the term Anthropocene? The term was popularized in 2000 by Paul Crutzen, a Nobel Prize-winning atmospheric chemist, and Eugene Stoermer, a biologist. Crutzen famously interrupted a conference to declare we were no longer in the Holocene.

What is the Meghalayan Age? The Meghalayan is the current age of the Holocene epoch. It began approximately 4,200 years ago. It is defined by a mega-drought that impacted civilizations across Egypt, Greece, and the Indus Valley.

Will there be another vote? According to the statutes of the International Commission on Stratigraphy, a rejected proposal cannot be voted on again for ten years. However, the debate over how to categorize human impact in geological terms will continue in scientific journals and conferences.