Climate stage· The columns of time
Eemian
130 ka → 115 ka
The last interglacial before our own, warmer than the present, with seas that stood several metres higher. Nothing in the recent past comes closer to a rehearsal of a warm world.
What the evidence shows
A probabilistic assessment of the evidence concludes that global sea level during the interval that specialists number MIS 5e was very likely at least 6 metres above present, with a two in three chance that it exceeded 8. That is more water than either polar ice sheet could supply alone, which is why the Eemian is studied so closely: it is a measured case of a world slightly warmer than ours. The same orbital forcing that warmed the interglacial also strengthened the African monsoon, and one of the green Sahara periods falls here; those are the windows in which the desert stops being a barrier and becomes a corridor between the African tropics and the Mediterranean.
Bounds and conventions
The sea level figure is a probability, not a measurement: it comes from combining many local records, each corrected for how the ground beneath it has risen or sunk since. The lower bound of six metres is far more secure than any single higher value.
MIS 5e, the last interglacial before our own. Its recent boundary, around 115 ka, is a convention: the cooling was gradual.
Sources
- Lisiecki, L. E., Raymo, M. E. (2005). A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003.
- Kopp, R. E. et al. (2009). Probabilistic assessment of sea level during the last interglacial stage. Nature 462, 863-867.
- Larrasoaña, J. C., Roberts, A. P., Rohling, E. J. (2013). Dynamics of Green Sahara Periods and Their Role in Hominin Evolution. PLoS ONE 8(10), e76514.