The Last Glacial Maximum and human refugia

Date

c. 26,500 – 19,000 years ago

Category

Environment & climate

Region

Global (Eurasia, Africa, Americas)

Era

Prehistory

Significance

The Last Glacial Maximum (LGM) was the most recent interval of maximum global ice cover, when continental ice sheets over North America (Laurentide), northern Europe and Scandinavia reached their greatest extent, roughly between 26,500 and 19,000 years ago.

Vast volumes of water were locked in ice, lowering global sea levels by about 120 metres and exposing continental shelves. Average temperatures fell sharply and habitable zones contracted, forcing human and animal populations into climatically milder 'refugia' such as Iberia (Franco-Cantabrian region), the Italian and Balkan peninsulas, and parts of Ukraine, while sub-Saharan Africa and Southeast Asia remained comparatively buffered. Population sizes shrank and fragmented, producing genetic bottlenecks and drift that reshaped human genetic diversity; estimates of Europe's LGM population range from a few thousand to over a hundred thousand. The recolonisation of northern latitudes during the subsequent deglaciation traces directly back to these refugial populations. The LGM provides the climatic backdrop for the Upper Palaeolithic in Eurasia and conditioned the timing and routes of later human dispersals, including the peopling of the Americas.

Related environment & climate events

• The Pleistocene–Holocene boundary and the start of the Holocene
  c. 11,700 years ago (c. 9700 BCE)
• End of the African Humid Period and Desertification of the Sahara
  c. 3500–2700 BCE
• Late Pleistocene megafaunal extinctions and the overkill-vs-climate debate
  c. 15,000 – 10,000 years ago
• The 8.2-kiloyear abrupt cooling event
  c. 6200 BCE
• The Toba super-eruption and the disputed 'volcanic winter'
  c. 74,000 years ago
• The Younger Dryas cold reversal
  c. 12,900 – 11,700 years ago

Further reading

A New Green History of the World

The wider story

A New Green History of the World

Clive Ponting

The classic accessible account of how environment and climate have shaped human history.

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