The Anthropocene is a proposed geological epoch defined by humanity’s measurable, permanent impact on Earth’s geology and ecosystems. The word combines the Greek “anthropo” (human) and “cene” (new), and it describes the idea that human activity has altered the planet so fundamentally that it constitutes a new chapter in Earth’s 4.5-billion-year history. Chemist Paul Crutzen and biologist Eugene Stoermer introduced the term in 2000.
Why Scientists Proposed a New Epoch
Earth’s history is divided into named time periods based on evidence preserved in rock, ice, and sediment. The current officially recognized epoch is the Holocene, which began roughly 11,700 years ago as the last ice age ended. The case for the Anthropocene rests on a simple but striking observation: the physical and chemical signatures humans are leaving in Earth’s geological record are unlike anything in the Holocene.
Atmospheric carbon dioxide sat at roughly 280 parts per million for nearly 6,000 years of human civilization. By 2022, NOAA measurements at Mauna Loa Observatory in Hawaii recorded 421 ppm, more than 50 percent higher than pre-industrial levels. That shift shows up in ice cores and ocean sediments the same way volcanic eruptions and asteroid impacts show up in older rock layers. But CO2 is just one signal. Plutonium from nuclear weapons testing in the 1940s and 1950s settled into lake beds and soil worldwide, creating a sharp, unmistakable chemical marker. At Crawford Lake in Ontario, Canada, scientists found this plutonium spike preserved in annual layers of lake sediment, followed by an equally sharp drop after the 1963 nuclear test ban treaty.
The Great Acceleration After 1950
One of the most important concepts behind the Anthropocene is the “Great Acceleration,” a term for the dramatic surge in human activity and environmental change that began around 1950. Researchers tracking 24 global indicators, 12 measuring human activity (economic growth, population, energy use, water consumption, transportation) and 12 measuring environmental change (greenhouse gas levels, ocean acidification, deforestation, biodiversity loss), found a consistent pattern. Nearly all the graphs bend sharply upward at the same moment: the mid-twentieth century.
Before 1950, human impacts were significant but regional. After 1950, those impacts became global and began driving changes in Earth’s core systems, its carbon cycle, nitrogen cycle, and biodiversity, that fall outside the normal range of variation seen during the entire Holocene. The researchers behind the Great Acceleration framework noted that the shift wasn’t gradual. It was abrupt enough to pinpoint, with some scientists even suggesting a symbolic start date: July 16, 1945, when the first atomic bomb was detonated in New Mexico.
When Does It Start?
The start date has been one of the most debated questions in the Anthropocene discussion. Early proposals placed the boundary at the Industrial Revolution in the late 1700s, when fossil fuel use began reshaping the atmosphere. Others argued for 1610, a date tied to a measurable dip in atmospheric CO2 caused by the deaths of tens of millions of Indigenous people in the Americas after European colonization. With massive populations gone, forests regrew across abandoned farmland and pulled enough carbon from the air to leave a detectable trace in Antarctic ice cores.
In 2019, the Anthropocene Working Group, the scientific body tasked with evaluating the proposal, voted to place the start at the mid-twentieth century Great Acceleration, using radionuclides (the radioactive fallout from nuclear testing) as the primary marker. This choice reflects the principle that a geological boundary needs a clear, globally synchronous signal in the physical record, and nuclear fallout provides exactly that.
It’s Not Officially Recognized
Despite widespread use of the term in science, media, and culture, the Anthropocene is not a formally recognized unit of geological time. In March 2024, the International Commission on Stratigraphy’s Subcommission on Quaternary Stratigraphy voted to reject the proposal to formalize the Anthropocene as an epoch. The International Union of Geological Sciences approved that rejection.
The vote didn’t mean scientists deny that humans are reshaping the planet. The disagreement was procedural and definitional. Some geologists felt that an epoch, which in Earth’s history typically spans millions of years, was the wrong category for changes measured in decades. Others argued the proposal was too narrowly defined, focusing on a single site (Crawford Lake) and a single marker (plutonium), when human impacts began at different times in different places. The term remains widely used in scientific literature and public discourse. It simply doesn’t appear on the official Geologic Time Scale.
The Scale of Biological Change
One of the most consequential dimensions of the Anthropocene concept is what’s happening to other species. Current extinction rates are estimated at 100 to 1,000 times higher than the natural background rate, the pace at which species would disappear without human influence. That background rate sits at roughly 0.1 to 1 extinction per million species per year. A 2022 analysis in Biological Reviews estimated that 150,000 to 260,000 species have gone extinct in the roughly 500 years since 1500, translating to 300 to 520 extinctions per year across an estimated two million known species.
These numbers have led many biologists to describe the current period as a sixth mass extinction, comparable in trajectory (though not yet in total scale) to the five previous mass extinction events in Earth’s history, including the one that killed the dinosaurs 66 million years ago. The driving forces are habitat destruction, pollution, climate change, invasive species, and overexploitation, all amplified by the same post-1950 acceleration visible in other indicators.
Alternative Names and Critiques
Not everyone agrees that “Anthropocene” is the right word. The term implies that humans as a whole are responsible, but critics point out that the environmental destruction driving this proposed epoch is not evenly distributed across all human societies. Several alternative names have been proposed to sharpen the diagnosis.
“Capitalocene,” a term first proposed by historian Andreas Malm in 2009, frames the crisis as a product of capitalism specifically, not humanity in general. “Plantationocene” traces the damage to the colonial plantation system that reorganized land, labor, and ecosystems on a global scale. Donna Haraway, a prominent scholar in science and technology studies, has argued for “Chthulucene,” a term meant to emphasize that humans are part of a larger web of living systems rather than separate masters of the planet. These aren’t just academic word games. Each name carries a different argument about what caused the crisis and, by extension, what kinds of responses make sense.
Ecologist Anna Tsing has offered another lens: the Holocene was the long period when refugia, places where biodiversity could recover after disruptions like fires, droughts, or deforestation, still existed in abundance. What makes the current moment different is the systematic destruction of those refugia. When the places that allow ecosystems to bounce back are themselves gone, the capacity for recovery disappears with them.