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End of the last ice age (Holocene begins)
11,700 years ago· Event· Earth, climate & extinctions
Well establishedStrong fossil, genetic or geological evidence.
The warm, stable epoch we live in, which began 11,700 years ago when the last ice age's final cold snap ended abruptly.
See it on the Life map →What happened
The last glacial period peaked about 26,000–19,000 years ago, then warmed in fits, interrupted by a cold snap called the Younger Dryas. When it ended, 11,700 years ago, Greenland warmed by perhaps 10°C within decades. Ice sheets kept melting for thousands of years. Sea level, about 120 meters below today's at the ice peak, rose until roughly 7,000 years ago, drowning Beringia, the land under the North Sea, and the floor of the Yellow Sea between Korea and China.
Why it matters
Its relatively steady, warm climate made farming, permanent villages and eventually cities possible; all of recorded human history fits inside it.
The evidence (fossils, genes, rocks)
Greenland ice cores: in 2008 the start was formally fixed at a level in the NGRIP core where dust, snowfall and oxygen isotopes shift sharply. Pollen in lake mud and drowned shorelines confirm the change.
Still debated
Exactly what triggered the Younger Dryas cold snap; a flood of meltwater slowing Atlantic currents is the leading idea, while a comet impact is a disputed alternative.
Connections (3)
▸Pleistocene ice ages ended in End of the last ice age (Holocene begins)Well established
The connection
The last glacial period gave way in fits: warming from about 19,000 years ago, then the Younger Dryas cold snap from about 12,900, then abrupt warming. That final jump, 11,700 years ago, marks the Holocene's start. Strictly, the Holocene is an interglacial: the ice-age cycles have paused, not necessarily ended.
When and how
Worldwide, 11,700 years before the year 2000; formally defined in 2008 by a level in the NGRIP ice core from Greenland.
The evidence
Ice cores, ocean sediments and lake records show the warming in sequence; counting annual layers in Greenland cores dates it to within about a century.
Debates and open questions
When the next glacial period would naturally begin, and how much human carbon emissions have postponed it, likely by tens of thousands of years.
▸Milankovitch cycles timed the warming that began End of the last ice age (Holocene begins)Strong evidence
The connection
After about 20,000 years ago, orbital shifts raised northern summer sunshine. Ice sheets began melting, carbon dioxide rose from about 190 to 280 parts per million, and warming spread worldwide, with setbacks such as the Younger Dryas cold snap. The Holocene, our current warm interval, began 11,700 years ago as that last cold spell ended.
When and how
Worldwide, about 20,000 to 11,700 years ago; the Holocene's start is officially defined in a Greenland ice core.
How sure are we?
Ice cores show carbon dioxide and temperature rising together; sea level rose about 120 meters as ice melted, recorded in drowned reefs and coastlines.
Debates and open questions
Why the Holocene has been so stable, and whether early farming's greenhouse gases helped keep the next ice age away, as William Ruddiman has argued.
▸End of the last ice age (Holocene begins) provided the stable climate for Agriculture beginsStrong evidence
The connection
Ice-age climate swung so wildly, decade to decade, that relying on planted crops would have been risky, and low carbon dioxide limited plant growth. The Holocene's warmer, wetter, steadier climate let wild cereals thrive and made farming dependable. Within a few thousand years of its start, farming arose independently in several regions.
When and how
Fertile Crescent from about 11,500 years ago, China about 10,000–9,000, Mexico about 9,000 and New Guinea about 7,000 years ago, and later elsewhere.
How sure are we?
Farming began on several continents soon after 11,700 years ago, and climate records show Pleistocene instability; Peter Richerson and colleagues made this case in 2001.
Debates and open questions
Climate made farming possible but does not explain why people chose it; population growth, social change and feasting are also argued.