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A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an
ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents an ...

ice age
that is marked by colder temperatures and
glacier A glacier (; ) is a persistent body of dense ice Ice is into a state. Depending on the presence of such as particles of soil or bubbles of air, it can appear transparent or a more or less bluish-white color. In the , ice is abunda ...

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 period A glacial period (alternatively glacial or ...
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 The Holocene ( ) is the current geological epoch In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age (geology), age but shorter than a period (geology), period. The current epoch is the Holocene E ...
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 The Cenozoic ( ; ) is Earth's current geological era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal ...
, which started about 2.6 million years
before present Before Present (BP) years is a time scale used mainly in archaeology Archaeology or archeology is the study of human activity through the recovery and analysis of material culture. Archaeology is often considered a branch of socio-cultural ...
, 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 Stage, Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Riss-Würm) wa ...
interglacial.


Last Glacial Period

The last glacial period was the most recent glacial period within the
Quaternary glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age#REDIRECT Ice age {{ ...
. It occurred in the
Pleistocene The Pleistocene ( , often referred to as the ''Ice Age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the earth’s most recent period of repeated glaciations. Before a change finally ...
, 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 Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remain ...

Northern Hemisphere
and have different names, depending on their geographic distributions: ''Wisconsin'' (in
North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continen ...

North America
), ''Devensian'' (in
Great Britain Great Britain is an island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atoll An atoll (), ...

Great Britain
), ''Midlandian'' (in
Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic. It is separated from Great Britain to its east by the North Channel (Great Britain and Ireland), North Channel, the Irish Sea ...

Ireland
), ''Würm'' (in the
Alps The Alps ; german: Alpen ; it, Alpi ; rm, Alps; sl, Alpe ) are the highest and most extensive mountain range A mountain range is a series of mountains ranged in a line and connected by high ground. A mountain system or mountain belt ...

Alps
), ''Weichsel'' (in northern
Central Europe Central Europe is an area of Europe Europe is a which is also recognised as part of , located entirely in the and mostly in the . It comprises the westernmost peninsulas of the of Eurasia, it shares the continental landmass of with both ...

Central Europe
), ''Dali'' (in
East China East China () is a geographical and a loosely defined cultural region In geography, regions are areas that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and the interacti ...

East China
), ''Beiye'' (in
North China North China, or Huabei ( ) is a geographical region of China, consisting of the provinces of Beijing Beijing ( ; ; ), Chinese postal romanization, alternatively romanized as Peking ( ), is the Capital city, capital of the People's Rep ...

North China
), ''Taibai'' (in
Shaanxi Shaanxi (; , ; Chinese postal romanization, alternately Shensi) is a landlocked Provinces of China, province of the China, People's Republic of China. Officially part of Northwest China, it borders the province-level divisions of Shanxi (NE, ...

Shaanxi
) ''Luoji Shan'' (in southwest
Sichuan Sichuan (; , ; alternatively romanized as Szechuan or Szechwan) is a landlocked province A province is almost always an administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, admini ...

Sichuan
), ''Zagunao'' (in northwest
Sichuan Sichuan (; , ; alternatively romanized as Szechuan or Szechwan) is a landlocked province A province is almost always an administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, admini ...

Sichuan
), ''Tianchi'' (in the
Tian Shan The Tian Shan,; dng, Тянсан, ; otk, 𐰴𐰣 𐱅𐰭𐰼𐰃, ; tr, Tanrı Dağı; mn, Тэнгэр уул, ; ug, تەڭرىتاغ, , ; kk, Тәңіртауы / Алатау, , ; ky, Теңир-Тоо / Ала-Тоо, , ; uz, Tyan- ...

Tian Shan
) ''Jomolungma'' (in the
Himalayas The Himalayas, or Himalaya (; Sanskrit Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language of South Asia that belongs to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It ar ...

Himalayas
), and ''Llanquihue'' (in
Chile Chile, officially the Republic of Chile, is a country in the western part of South America South America is a entirely in the and mostly in the , with a relatively small portion in the . It can also be described as the southern ...

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 In glaciology Lateral moraine on a glacier joining the Gorner Glacier, Zermatt">Gorner_Gla ...
about 26,500 BP. In
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

Europe
, the ice sheet reached
Northern Germany Northern Germany (german: Norddeutschland) is the region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and phenomen ...
. 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 Berger is a surname in both German language, German and French language, French, although there is no etymological connection between the names in the two languages. The French surname is an occupational name for a shepherd, from Old French ''bergie ...

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

{{DEFAULTSORT:Glacial Period
Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Period, a descriptor for a historical or period drama ...