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The Anthropocene
proposed start c. 1950; formal epoch rejected 2024· Theory or idea· Earth, climate & extinctions
DebatedScientists disagree about when, how or why.
The proposal that humans have changed Earth so much that a new geological epoch began, around 1950.
See it on the Life map →What happened
Chemist Paul Crutzen popularized the term in 2000. Humans now move more sediment than rivers, have raised carbon dioxide from about 280 to over 420 parts per million, and by about 2020 human-made materials such as concrete outweighed all living things. An expert working group proposed a start around 1950, marked by plutonium fallout from bomb tests, with Crawford Lake in Ontario as the reference site. In March 2024 geologists voted against making it a formal epoch. It remains widely used informally.
Why it matters
It frames humanity as a geological force comparable to ice ages or asteroid impacts, and ties together climate change, extinctions and pollution.
The evidence (fossils, genes, rocks)
Rock, lake and ice layers record plutonium, microplastics, soot, fertilizer nitrogen and a sharp carbon dioxide rise; the 2024 rejection vote by the geologists' Quaternary subcommission is on record.
Still debated
Whether it is best treated as an epoch, a drawn-out 'event' like the rise of oxygen, or neither; and when significant human influence really began.
Inside this (4)
Connections (4)
▸Agriculture begins started the human reshaping behind The AnthropoceneDebated
The connection
Farming began the large-scale human reshaping of Earth: forests cleared, soils plowed, wild species replaced by crops and livestock. Farmland now covers about half of habitable land, and livestock and humans make up roughly 96% of mammal body weight. Some scientists trace the Anthropocene's roots to early farming, which may have raised carbon dioxide and methane thousands of years ago.
When and how
Fertile Crescent from about 11,500 years ago, then independently in China, the Americas, New Guinea and Africa; the 'early Anthropocene' idea was proposed by William Ruddiman in 2003.
How sure are we?
Pollen cores record forest clearance; ice cores show methane and carbon dioxide rising unusually several thousand years ago, though the cause is disputed.
Debates and open questions
Whether early farming really changed climate, and whether such a gradual start can mark an epoch; the working group rejected it as too spread out over millennia.
▸Columbian exchange is one proposed start of The AnthropoceneDebated
The connection
After 1492 crops, animals and diseases crossed between the hemispheres, mixing life globally. Epidemics killed a large share of the Americas' Indigenous peoples, and abandoned farmland regrew as forest, drawing down carbon dioxide. Simon Lewis and Mark Maslin argued this caused a 1610 dip in Antarctic ice cores, the 'Orbis spike', and proposed it as the Anthropocene's start.
When and how
The Americas, Europe, Africa and Asia, from 1492; the 1610 proposal was published by Lewis and Maslin in Nature in 2015.
How sure are we?
Antarctic ice cores show a carbon dioxide dip of about 7–10 parts per million around 1610, and sediments worldwide begin showing crops and species from other continents.
Debates and open questions
Death toll estimates vary widely, into the tens of millions; how much of the dip came from forest regrowth rather than natural cooling is disputed.
▸Industrial Revolution & fossil fuels is one proposed start of The AnthropoceneDebated
The connection
Coal, and later oil, let humans burn ancient carbon at vast scale, raising carbon dioxide, spreading soot and powering explosive population growth. When Paul Crutzen proposed the Anthropocene in 2000, he dated it to the late 1700s, when ice cores show carbon dioxide starting to climb and James Watt improved the steam engine.
When and how
Britain from about 1760, spreading to Europe, North America and Asia; Crutzen's proposal came at a scientific meeting in Mexico in 2000, then in Nature in 2002.
How sure are we?
Ice cores and air measurements show carbon dioxide rising from about 280 parts per million around 1800 to over 420 today; lake sediments record soot and fly ash.
Debates and open questions
Industry spread unevenly over two centuries, so geologists preferred the sharper, worldwide 1950s signal, and in 2024 they rejected a formal epoch altogether.
▸A sixth mass extinction? is often cited as a sign of The AnthropoceneDebated
The connection
Species are now vanishing far faster than the natural background rate, through habitat loss, hunting, invasive species and climate change. These losses, plus the global mixing of species, will leave a fossil record that future geologists could read as a boundary, much as past mass extinctions mark the boundaries between geological periods.
When and how
Worldwide, since about 1500; popularized by Richard Leakey and Roger Lewin's The Sixth Extinction (1995) and Elizabeth Kolbert's book of the same name (2014).
How sure are we?
The IUCN Red List documents roughly 900 extinctions since 1500, and a 2019 UN-backed assessment (IPBES) estimated about a million species are threatened.
Debates and open questions
Whether losses have reached mass-extinction scale, usually about 75% of species, or are only heading there; the proposed formal marker was plutonium fallout, not extinctions.