Climate stage· The columns of time

Last glacial

115 ka → 11.7 ka

The last glacial, from 115,000 to 11,700 years ago, is about a hundred thousand years of mostly cold and unstable climate.

Last glacial stage, running from MIS 5d to MIS 2, that is, about a hundred thousand years of predominantly cold and unstable climate. It is during this interval that the species definitively leaves Africa, reaches Australia, establishes itself in Europe and enters the Americas.

What the evidence shows

The cold constituted an obstacle and simultaneously a condition of passage. The lowering of sea level exposed the continental shelves, joined Australia and New Guinea into a single continent called Sahul, attached Britain to the European mainland and emerged Beringia between Siberia and Alaska. None of these passages existed without water immobilised as ice elsewhere. The stage extends from MIS 5d to MIS 2; its thermal minimum, the Last Glacial Maximum, is the subject of a separate band, and most of these passages were open and used before it.

Bounds and conventions

A single colour represents a stage whose internal variability is strong. Three synchronised Greenland cores distinguish within it a long series of abrupt warmings, called Dansgaard-Oeschger events and numbered in the stratigraphic framework established on those cores; several altered temperature by several degrees within a few decades. Ice supplies that measurement by the inverse of the procedure used for marine shells: water vapour loses more of its heavy molecules along its path the more it cools, so that snow falling in cold air is poorer in heavy oxygen than that of temperate air, and each annual layer preserves the temperature of the corresponding year. The description as cold holds on average and not for the experience of the populations concerned.

MIS 5d to MIS 2: a hundred thousand years of mostly cold, unstable climate, with temperate interstadials that this row does not detail.