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A glacial period is an interval of time within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate within an ice age. The last glacial period ended about 10,000 to 15,000 years ago; the current Holocene epoch marked the beginning of the interglacial we are presently in.

Main articles: Quaternary glaciation and timeline of glaciation

Glacial and interglacial cycles of the late Pleistocene epoch within the Quaternary glaciation, as represented by atmospheric CO₂, measured from ice core samples going back 650,000 years

Within in the Quaternary glaciation (2.58 Ma to present), there have been various glacials and interglacials.

Within the Pleistocene extent of the Quaternary ice age, there have been the following glacials and interglacials, from earliest to latest:

• Bramertonian interglacial
• Pre-Pastonian glaciation
• Pastonian interglacial
• Beestonian stage
• Cromerian interglacial
• Kansan glaciation
• Hoxnian interglacial
• Wolstonian glaciation
• Eemian interglacial
• Last glacial period

Main article: Last glacial period

The last glacial period was the most recent glacial period within the current ice age, occurring in the Pleistocene epoch, which began about 70,000 and ended between 10,000 and 15,000 Before Present (BP). The glaciations that occurred during this glacial period covered many areas of the Northern Hemisphere, and have different names, depending on their geographic distributions: Wisconsin (in North America), Devensian (in the British Isles), Midlandian (in Ireland), Würm (in the Alps), and Weichsel (in northern central Europe). The glacial advance reached its maximum extent about 18,000 BP. In Europe, the ice sheet reached northern Germany.

See also: Milankovitch cycles

Since orbital variations are predictable^[1], if one has a model that relates orbital variations to climate, it is possible to run such a model forward to "predict" future climate. Two caveats are necessary: that anthropogenic effects (global warming) are likely to exert a larger influence over the short term, and that the mechanism by which orbital forcing influences climate is not well understood.

An often-cited 1980 study by Imbrie and Imbrie determined that "Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6,000 years ago will continue for the next 23,000 years."^[2]

More recent work by Berger and Loutre suggests that the current warm climate may last another 50,000 years.^[3]

• Glacier
• Geologic time scale
• Glacial history of Minnesota