The Eemian interglacial era (Sangamon era in North America) is the second-to-latest interglacial era of the Ice age. It began about 131,000 years ago, consisted of an early warm period of about 3,000 to 4,000 years duration, a rapid cooling and then a much slower cooling leading to the next glacial era. However, recent ice core analyses have shown that during the course of the Eemian, there were several short periods in which glacial conditions prevailed. The onset and close of these periods were very abrupt. The warmest peak of the Eemian was around 125,000 years ago, when forests reached as far north as North Cape (now tundra) in northern Norway. Hardwood trees like Hazel and Oak grew as north as in Oulu, Finland. Sea levels at that time were higher than they were now, possibly indicating greater deglaciation of even more of the world than now (one presumes the ice caps of Greenland and Antarctica). Scandinavia was an island.

At the peak of the Eemian, the world was generally warmer and wetter than it now is. Trees grew as far north as Baffin Island in the Canadian arctic archipelago, and the prairie-forest boundary in the Great Plains lay further west -- near Lubbock, Texas instead of near Dallas, Texas where it now exists. The era quickly cooled to conditions cooler and drier than the present, and by 114,000 years ago, a glacial era had returned.