Climate stage· The columns of time

Eemian

130 ka → 115 ka

The Eemian, from 130,000 to 115,000 years ago, is the last interglacial before our own.

Last interglacial before the present one, corresponding to substage MIS 5e. Polar temperatures exceed those of the present by about 3 to 5 °C, and global sea level stands several metres above the current level: the Eemian is thus the principal available example of a world warmer than ours.

What the evidence shows

A probabilistic assessment of the whole body of data concludes that global sea level during MIS 5e very likely stood at least 6 metres above the present level, with a two-thirds probability of exceeding 8 metres. That volume exceeds what either polar ice sheet could supply alone, which implies a contribution from both. The same orbital forcing that warmed the interglacial strengthened the African monsoon, and one of the green Sahara phases falls within this interval: the desert then ceases to be a barrier and constitutes a corridor between the African tropics and the Mediterranean.

Bounds and conventions

The sea level value is a probabilistic estimate and not a direct measurement. It results from combining local records, each corrected for the vertical movement of the ground that carries it, a phenomenon called glacial isostatic adjustment: an ice sheet three kilometres thick depresses the crust beneath it and the material displaced at depth raises a peripheral bulge; on melting, the depressed region rises for millennia while the bulge subsides. The present altitude of an ancient beach therefore combines sea level and ground movement. The lower bound of six metres is considerably better established than any higher value taken in isolation.

MIS 5e, the last interglacial before ours. Its recent boundary, around 115 ka, is conventional: the cooling was gradual.