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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 glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier A glacier ( or ) is a persistent body of dense ice that is constantly movi ...
s 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 and ...

ice age
. The current
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 ...
interglacial began at the end of 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 ...
, about 11,700 years ago.


Pleistocene

During the 2.5 million years of 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 ...
, numerous glacials, or significant advances of continental ice sheets, 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
and
Europe Europe 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 continents. Ordered ...

Europe
, occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter interglacials. During interglacials, such as the present one, the climate warms and the
tundra In physical geography Physical geography (also known as physiography) is one of the two fields of geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the ...

tundra
recedes polewards following the ice sheets. Forests return to areas that once supported tundra vegetation. Interglacials are identified on land or in shallow epicontinental seas by their paleontology. Floral and faunal remains of species pointing to temperate climate and indicating a specific age are used to identify particular interglacials. Commonly used are mammalian and molluscan species, pollen and plant macro-remains (seeds and fruits). However, many other fossil remains may be helpful: insects, ostracods, foraminifera, diatoms, etc. Recently, ice cores and
ocean sediment Marine sediment, or ocean sediment or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor. These particles have their origins in soil and Rock (geology), rocks and have been Sediment transport, transported f ...
cores provide more quantitative and accurately-dated evidence for temperatures and total ice volumes. Interglacials and glacials coincide with cyclic changes in
Earth's orbit Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi), and one complete orbit takes  days (1 sidereal year), during which time Earth has traveled 940 million km (584 million mi). Jean Meeus, ''Astron ...
. Three orbital variations contribute to interglacials. The first is a change in Earth's orbit around the Sun, or
eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off- center, in geometry * Eccentricity (graph theory) of a ...
. The second is a shift in the tilt of Earth's axis, or
obliquity In astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses mat ...
. The third is the wobbling motion of Earth's axis, or
precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In other ...
. In the
Southern Hemisphere The Southern Hemisphere is the half (hemisphere Hemisphere may refer to: * A half of a sphere As half of the Earth * A hemispheres of Earth, hemisphere of Earth ** Northern Hemisphere ** Southern Hemisphere ** Eastern Hemisphere ** Western He ...

Southern Hemisphere
, warmer summers occur when the lower-half of Earth is tilted toward the Sun and the planet is nearest the Sun in its elliptical orbit. Cooler summers occur when Earth is farthest from the Sun during the Southern Hemisphere summer. Such effects are more pronounced when the eccentricity of the orbit is large. When the obliquity is large, seasonal changes are more extreme. Interglacials are a useful tool for geological mapping and for anthropologists, as they can be used as a dating method for
hominid The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose ...
fossils. Brief periods of milder climate that occurred during the last glacial are called
interstadial Stadials and interstadials are phases dividing the Quaternary period, or the last 2.6 million years. Stadials are periods of colder climate while interstadials are periods of warmer climate. Each Quaternary climate phase is associated with a Mari ...
s. Most, but not all, interstadials are shorter than interglacials. Interstadial climates may have been relatively warm, but not necessarily. Because the colder periods (stadials) have often been very dry, wetter (not necessarily warmer) periods have been registered in the sedimentary record as interstadials as well. The oxygen isotope ratio obtained from seabed sediment
core sample . A pied butcherbird The pied butcherbird (''Cracticus nigrogularis'') is a songbird native to Australia. Described by John Gould in 1837, it is a black and white bird long with a long hooked bill. Its head and throat are black, making a disti ...

core sample
s, a
proxy Proxy may refer to: * Proxy or agent (law), a substitute authorized to act for another entity or a document which authorizes the agent so to act * Proxy (climate), a measured variable used to infer the value of a variable of interest in climate r ...
for the average global temperature, is an important source of information for changes in Earth's climate. An interglacial optimum, or climatic optimum of an interglacial, is the period within an interglacial that experienced the most 'favourable'
climate Climate is the long-term pattern of weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a la ...

climate
and often occurs during the middle of that interglacial. The climatic optimum of an interglacial both follows and is followed by phases within the same interglacial that experienced a less favourable climate (but still a 'better' climate than the one during the preceding or succeeding
glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age#REDIRECT Ice age {{Redirect category shell, 1= {{R from move {{R from ambiguous term {{R from other capitalisation {{R unprintwor ...
s). During an interglacial optimum, sea levels rise to their highest values, but not necessarily exactly at the same time as the climatic optimum.


Specific interglacials

The last six interglacials are: * Marine Isotope Stage 13 (524–474 thousand years ago). *
Hoxnian __NOTOC__ The Hoxnian Stage was a middle 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 pe ...
/ Holstein / Mindel-Riss / Marine Isotope Stage 11 (424–374 thousand years ago). * Purfleet Interglacial / Holstein / Mindel-Riss /
Marine Isotope Stage 9Marine Isotope Stage 9 (MIS 9) is a Marine Isotope Stage in the geological record. It is the final period of the Lower Paleolithic, and lasts from 337,000 to 300,000 years ago according to Lisiecki and Raymo's Lorraine Lisiecki#LR04 Benthic Stack (Li ...
(337–300 thousand years ago). * La Bouchet Interglacial / Arousa Interglacial / Aveley Interglacial / Marine Isotope Stage 7e (242–230 thousand years ago). MIS 7a, MIS 7b and MIS 7c may or may not be included. MIS 7d was a cold period dividing the MIS 7 interglacial into two distinct periods. MIS 7e contained the climatic optimum. *
Eemian The Eemian (also called the last interglacial, , Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Riss-Würm) was the which began ...
/
Marine Isotope Stage 5 Marine Isotope Stage 5 or MIS 5 is a Marine Isotope Stage in the geologic temperature record The geologic temperature record are changes in Earth Earth is the third planet from the Sun and the only astronomical object known to harbor li ...
e (130–115 thousand years ago). The preceding interglacial optimum occurred during the Late Pleistocene
Eemian Stage 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 ...
, 131–114 ka. During the Eemian the climatic optimum took place during
pollen zone Pollen zones are a system of subdividing the last glacial period and Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years before present Before Present (BP) years is a time scale used mainl ...
E4 in the type area (city of
Amersfoort Amersfoort is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: Penguin.Kuper, A. and Kuper, J., eds (1996) ''The Social Science Encyclopedia''. 2nd edition. London: Routledge. ...

Amersfoort
,
Netherlands ) , national_anthem = ( en, "William of Nassau") , image_map = EU-Netherlands.svg , map_caption = , image_map2 = BES islands location map.svg , map_caption2 = , image_map3 ...

Netherlands
). Here this zone is characterized by the expansion of ''
Quercus An oak is a tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including on ...

Quercus
'' (oak), ''
Corylus The hazel (''Corylus'') is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may al ...
'' (hazel), ''
Taxus ''Taxus'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including their ana ...

Taxus
'' (yew), ''
Ulmus Elms are deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists are agriculturists who grow f ...
'' (elm), ''
Fraxinus ''Fraxinus'' , English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become th ...
'' (ash), ''
Carpinus Hornbeams are hardwood is a popular hardwood Hardwood is wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees and other woody plants. It is an organic materiala natural composite mater ...
'' (hornbeam), and ''
Picea A spruce is a tree of the genus ''Picea'' , a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Earth. ''Picea'' is the sole genus ...

Picea
'' (spruce). During the Eemian Stage sea level was between 5 and 9.4 meters higher than today and the water temperature of the
North Sea The North Sea is a sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
was about 2 °C higher than at present. *
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 ...
(12,000 years ago to the present). During the present interglacial, the Holocene, the climatic optimum occurred during the
Subboreal The Subboreal is a climatic period, immediately before the present one, of 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 (geo ...
(5 to 2.5 ka BP, which corresponds to 3000 BC–500 BC) and
Atlanticum
Atlanticum
(9 to 5 ka, which corresponds to roughly 7000 BC–3000 BC). The current climatic phase following this climatic optimum is still within the same interglacial (the Holocene). That warm period was followed by a gradual decline until about 2000 years ago, with another warm period until the
Little Ice Age The Little Ice Age (LIA) was a period of cooling that occurred after the Medieval Warm Period The Medieval Warm Period (MWP) also known as the Medieval Climate Optimum, or Medieval Climatic Anomaly was a time of warm climate Climate is the ...
(1250–1850).


See also

* Greenhouse and icehouse Earth *
Milankovitch cycles Milankovitch cycles describe the collective effects of changes in the 's movements on its over thousands of years. The term is named for n and . In the 1920s, he hypothesized that variations in , , and resulted in cyclical variation in the r ...

Milankovitch cycles
*
Snowball Earth The Snowball Earth hypothesis proposes that, during one or more of Earth's Greenhouse and icehouse Earth, icehouse climates, the Earth's surface, planet's surface became entirely or nearly entirely frozen. It is believed that this occurred someti ...
*
Interstadial Stadials and interstadials are phases dividing the Quaternary period, or the last 2.6 million years. Stadials are periods of colder climate while interstadials are periods of warmer climate. Each Quaternary climate phase is associated with a Mari ...
periods *
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 ...
*
Timeline of glaciation A timeline is a display of a list of events in Chronology, chronological order. It is typically a graphic design showing a long bar labelled with calendar date, dates paralleling it, and usually contemporaneous events. Timelines can use any ...


References

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