A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances.

Interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...

s, on the other hand, are periods of warmer climate between glacial periods. The Last Glacial Period ended about 15,000 years ago. The Holocene is the current interglacial. A time with no glaciers on Earth is considered a greenhouse climate state.

Quaternary Period

Within the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

, which started about 2.6 million years before present, there have been a number of glacials and interglacials. At least eight glacial cycles have occurred in the last 740,000 years alone.

Penultimate Glacial Period

The Penultimate Glacial Period (PGP) is the glacial period that occurred before the Last Glacial Period. It began about 194,000 years ago and ended 135,000 years ago, with the beginning of the

Eemian The Eemian (also called the last interglacial, Sangamonian, Sangamonian Stage, Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Ri ...

interglacial.

Last Glacial Period

The last glacial period was the most recent glacial period within the Quaternary glaciation. It occurred in the Pleistocene, which began about 110,000 years ago and ended about 15,000 years ago. The glaciations that occurred during the glacial period covered many areas of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

and have different names, depending on their geographic distributions: ''Wisconsin'' (in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

), ''Devensian'' (in Great Britain), ''Midlandian'' (in Ireland), ''Würm'' (in the Alps), ''Weichsel'' (in northern Central Europe), ''Dali'' (in East China), ''Beiye'' (in

North China North China, or Huabei () is a List of regions of China, geographical region of China, consisting of the provinces of Beijing, Tianjin, Hebei, Shanxi and Inner Mongolia. Part of the larger region of Northern China (''Beifang''), it lies north ...

), ''Taibai'' (in Shaanxi) ''Luoji Shan'' (in southwest Sichuan), ''Zagunao'' (in northwest Sichuan), ''Tianchi'' (in the Tian Shan) ''Jomolungma'' (in the Himalayas), and ''Llanquihue'' (in Chile). The glacial advance reached the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eur ...

about 26,500 BP. In Europe, the ice sheet reached

Northern Germany Northern Germany (german: link=no, Norddeutschland) is a linguistic, geographic, socio-cultural and historic region in the northern part of Germany which includes the coastal states of Schleswig-Holstein, Mecklenburg-Vorpommern and Lower Saxony an ...

. Over the last 650,000 years, there have been on average seven cycles of glacial advance and retreat.

Next glacial period

Since orbital variations are predictable, computer models that relate orbital variations to climate can predict future climate possibilities. Work by Berger and Loutre suggests that the current warm climate may last another 50,000 years. The amount of heat trapping (greenhouse) gases being emitted into the Earth's oceans and its atmosphere may delay the next glacial period by an additional 50,000 years.

References

External links

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