Eemian interglacial
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The Eemian interglacial era (known as the Sangamon interglacial in North America, the Ipswichian interglacial in the UK, and the Riss-Würm interglacial in the Alps) is the second-to-latest interglacial era of the Ice Age. It began about 131,000 years ago. Changes in orbital parameters from today (greater obliquity and eccentricity, and perihelion), known as the Milankovitch cycle, probably led to greater seasonal temperature variations in the Northern Hemisphere, although global annual means temperatures were probably similar to those of the Holocene. The Eemian climate is believed to have been about as stable as the Holocene (see ice core), except probably warmer than. The warmest peak of the Eemian was around 125,000 years ago, when forests reached as far north as North Cape (which is now tundra) in northern Norway well above the Arctic Circle at . Hardwood trees like hazel and oak grew as far north as Oulu, Finland. Sea levels at that time were 5-8 meters higher than they are now, possibly indicating greater deglaciation than today (mostly from partial melting of the ice sheet of Greenland).([Aber 2004]) Scandinavia was an island due to the inundation of vast areas of northern Europe and the West Siberian Plain.
At the peak of the Eemian, the northern hemisphere winters were generally warmer and wetter than now, though some areas were actually slightly cooler than today. Trees grew as far north as southern Baffin Island in the Canadian Arctic Archipelago instead of only as far north as Kuujjuaq in northern Quebec, and the prairie-forest boundary in the Great Plains of the United States lay further west — near Lubbock, Texas, instead of near Dallas, Texas, where the boundary 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.
Kaspar et al. (GRL, 2005) perform a comparison of a coupled GCM with reconstructed Eemian temperatures for Europe. Central Europe (north of the Alps) is found to be 1-2°C warmer than present; south of the alps conditions are 1-2°C cooler than today. The model (forced with observed GHG concentrations and Eemian orbital parameters) generally reproduces these observations, and hence they conclude that these factors are enough to explain the Eemian temperatures.
Sea level
Sea level at peak was probably 4-6m higher than today (references in Overpeck et al.), with much of this coming from Greenland but some likely to have come from Antarctica. Global mean sea surface temperatures are not thought to have been significantly higher than holocene, hence the thermal expansion difference from today is small.
Ipswichian interglacial
This name is used by British geologists and archaeologists who named it after the town of Ipswich in the English county of Suffolk, where some of the deposits it created were first found.See also
References
- Kaspar, F et al.; GRL 2005, v32 L11703
- Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Daniel R. Muhs, Richard B. Alley, Jeffrey T. Kiehl, Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise, Science 311, 24 March 2006.
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