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The late Paleozoic icehouse, also known as the Late Paleozoic Ice Age (LPIA) and formerly known as the Karoo ice age, was an ice age that began in the
Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...
and ended in the
Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...
, occurring from 360 to 255 million years ago (Mya), and large land-based ice-sheets were then present on Earth's surface. It was the second major icehouse period of the
Phanerozoic The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 538.8 million years to the present, and it began with the Cambrian Period, when anima ...
. It is named after the
tillite image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
( Dwyka Group) found in the
Karoo Basin The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a perio ...
of western
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...
, where evidence for the ice age was first clearly identified in the 19th century. The
tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...
assembly of the continents of
Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...
and
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
into
Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
, in the
Hercynian The Variscan or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. Nomenclature The name ''Variscan'', comes f ...
- Alleghany
Orogeny Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted ...
, made a major continental land mass within the Antarctic region, and the closure of the
Rheic Ocean The Rheic Ocean was an ocean which separated two major palaeocontinents, Gondwana and Laurussia (Laurentia-Baltica-Avalonia). One of the principal oceans of the Palaeozoic, its sutures today stretch from Mexico to Turkey and its closure resulted ...
and
Iapetus Ocean The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoco ...
saw disruption of warm-water currents in the
Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the ...
Ocean and
Paleotethys The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; exi ...
Sea and an increase in carbon sequestration via
silicate weathering In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is a ...
, which led to progressive cooling of summers, and the snowfields accumulating in winters, which caused mountainous alpine
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
s to grow, and then spread out of highland areas. That made
continental glacier In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Las ...
s, which spread to cover much of Gondwana. Data from Serpukhovian and Moscovian marine strata of South China point to glacioeustasy being driven primarily by long-period eccentricity, with a cyclicity of about 0.405 million years, and the modulation of the amplitude of Earth's obliquity, with a cyclicity of approximately 1.2 million years. This is most similar to the early part of the Late Cenozoic Ice Age, from the
Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
to the
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Arctic ice cap The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall a ...
, suggesting the climate of this episode of time was relatively warm for an icehouse period. Evidence from the Middle Permian Lucaogou Formation of
Xinjiang Xinjiang, SASM/GNC: ''Xinjang''; zh, c=, p=Xīnjiāng; formerly romanized as Sinkiang (, ), officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwest ...
, China indicates that the climate of the time was particularly sensitive to the 1.2 million year long-period modulation cycle of obliquity. It also suggests that palaeolakes such as those found in the Junggar Basin likely played an important role as a carbon sink during the later stages of the LPIA, with their absorption and release of carbon dioxide acting as powerful feedback loops during
Milankovitch cycle Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term was coined and named after Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he hypoth ...
driven glacial and interglacial transitions. Interpretations of the LPIA vary, with some
researchers Research is " creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness ...
arguing it represented one continuous glacial event and others concluding that as many as twenty-five separate ice sheets across Gondwana developed, waxed, and waned independently and diachronously over the course of the Carboniferous and Permian, with the distribution of ice centres shifting as Gondwana drifted and its position relative to the
South Pole The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...
changed. At the beginning of the LPIA, ice centres were concentrated in western South America; they later shifted eastward across Africa and by the end of the ice age were concentrated in Australia. Evidence from sedimentary basins suggests individual ice centres lasted for approximately 10 million years, with their peaks alternating with periods of low or absent permanent ice coverage. The glacial episodes that occurred during the late
Famennian The Famennian is the latter of two faunal stages in the Late Devonian Epoch. The most recent estimate for its duration estimates that it lasted from around 371.1 million years ago to 359.3 million years ago. An earlier 2012 estimate, still used b ...
and late middle to early late
Tournaisian The Tournaisian is in the ICS geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous. The Tournaisian age lasted from Ma to Ma. It is preceded by the Famennian (the uppermost stage ...
are sometimes considered discrete glaciations separate from and preceding the LPIA proper that began between 335 and 330 Mya during the
Viséan The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from to Ma. It follows th ...
or
Serpukhovian The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from Ma to Ma. It is preceded by the Visean and is followed by ...
. Likewise, the more geographically limited glaciations that persisted in some parts of Gondwana until the last alpine glaciers melted in what is now eastern Australia around 255 Mya are sometimes not considered part of the LPIA proper either, which is said to have peaked during the
Asselian In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between and million years ago (Ma). ...
and early
Sakmarian In the geologic timescale, the Sakmarian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Sakmarian lasted between 293.52 and million years ago (Ma). It was preceded by the Asselian and followed by ...
and ended in the late Sakmarian around 290 Mya or near the
Artinskian In the geologic timescale, the Artinskian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Artinskian likely lasted between and million years ago (Ma) according to the most recent revision of the ...
-
Kungurian In the geologic timescale, the Kungurian is an age or stage of the Permian. It is the latest or upper of four subdivisions of the Cisuralian Epoch or Series. The Kungurian lasted between and million years ago (Ma). It was preceded by the Art ...
boundary and the associated Kungurian Carbon Isotopic Excursion under this more restricted definition. At least two major periods of glaciation within the LPIA proper are known: *The first
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 advances. Interglacials, on the other hand, are periods of warmer climate betw ...
occurred from the Serpukhovian to the Moscovian: ice sheets expanded from a core in southern Africa and South America. A relatively warm interglacial interval spanning the Kasimovian and Gzhelian, coinciding with the Alykaevo Climatic Optimum, occurred between this first major glacial period and the later second major glacial period. *The second glacial period occurred from the late
Gzhelian The Gzhelian ( ) is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from to Ma. It follows the Kas ...
across the Carboniferous-Permian boundary to the early Sakmarian; ice sheets expanded from a core in Australia and
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. From the late Sakmarian onward, and especially following the Artinskian Warming Event (AWE), these ice sheets declined, as indicated by a negative
δ18O In geochemistry, paleoclimatology and paleoceanography ''δ''18O or delta-O-18 is a measure of the ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O). It is commonly used as a measure of the temperature of precipitation, as a mea ...
excursion. Other, minor or more geographically limited glacial intervals have also been identified: *The aforementioned interval of transient glaciations spanning from the Famennian to the late Visean or earliest Serpukhovian. *A glacial interval limited to Australia spanning the latest Sakmarian and the Artinskian, known regionally as P2 (P1 coinciding with the Gondwana-wide glaciations during the Asselian and early Sakmarian). This regional glaciation occurred amidst a global pulse of net warming and deglaciation, as evidenced by the retreat of ice sheets in Central Africa and in the Karoo Basin. *A second, longer regional interval also limited to Australia from the middle Kungurian to the early
Capitanian In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian Epoch or Series. The Capitanian lasted between and million years ago. It was preceded by ...
, known as P3. Unlike the previous glaciations, this one and the following P4 glaciation were limited to alpine glaciation. *A final regional Australian interval lasting from the middle Capitanian to the late
Wuchiapingian In the geologic timescale, the Wuchiapingian or Wujiapingian (from in the Liangshan area of Hanzhong, Shaanxi Province) is an age or stage of the Permian. It is also the lower or earlier of two subdivisions of the Lopingian Epoch or Series. T ...
, known as P4. This glacial period was interrupted by a rapid warming interval corresponding to a surge in activity from the Emeishan Traps and corresponding
Capitanian mass extinction event The Capitanian mass extinction event, also known as the end-Guadalupian extinction event or the pre-Lopingian crisis was an extinction event that predated the end-Permian extinction event and occurred around 260 million years ago during a period ...
. The time intervals here referred to as glacial and interglacial periods represented intervals of several million years corresponding to colder and warmer icehouse intervals, respectively, were influenced by long term variations in palaeogeography, greenhouse gas levels, and geological processes such as rates of volcanism and of silicate weathering and should not be confused with shorter term cycles of glacials and interglacials that are driven by astronomical forcing caused by Milankovitch cycles.


Late Paleozoic glaciations

According to Eyles and Young, "Renewed Late Devonian glaciation is well documented in three large intracratonic basins in Brazil (Solimoes, Amazonas and Paranaiba basins) and in Bolivia. By the Early Carboniferous (c. 350 Ma) glacial strata were beginning to accumulate in sub-Andean basins of
Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...
,
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
and
Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to ...
. By the mid-Carboniferous glaciation had spread to Antarctica, Australia, southern Africa, the Indian Subcontinent, Asia and the Arabian Peninsula. During the Late Carboniferous glacial accumulation (c. 300 Ma) a very large area of Gondwana land mass was experiencing glacial conditions. The thickest glacial deposits of Permo-Carboniferous age are the Dwyka Formation (1000 m thick) in the
Karoo Basin The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a perio ...
in southern Africa, the Itararé Group of the
Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande ...
, Brazil (1400 m) and the
Carnarvon Basin The Carnarvon Basin is a geological basin located in the north west of Western Australia which extends from the Dampier Archipelago to the Murchison bioregion, and is the main geological feature that makes up the North West Shelf. The onsho ...
in eastern Australia. The Permo-Carboniferous glaciations are significant because of the marked glacio-
eustatic Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
changes in sea level that resulted and which are recorded in non-glacial basins. Late Paleozoic glaciation of Gondwana could be explained by the migration of the supercontinent across the South Pole." In northern
Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the no ...
glacial landforms like striations, rôche moutonnées and
chatter mark A chatter mark is one or, more commonly, a series of wedge shaped marks left by chipping of a bedrock surface by rock fragments carried in the base of a glacier ( glacial plucking). Marks tend to be crescent-shaped and oriented at right angles ...
s can be found buried beneath Late Carboniferous-Early Permian glacial deposits (
Edaga Arbi Glacials The Edaga Arbi Glacials are a Palaeozoic geological formation in Tigray (northern Ethiopia) and in Eritrea. The matrix is composed of grey, black and purple clays (locally silt), that contains rock fragments up to 6 metres across. Pollen dating y ...
). Glaciofluvial sandstones, moraines, boulder beds, glacially striated pavements, and other glacially derived geologic structures and beds are also known throughout the southern part of the Arabian Peninsula. In southern Victoria Land, Antarctica, the Metschel Tillite, made up of reworked Devonian Beacon Supergroup sedimentary strata along with Cambrian and Ordovician granitoids and some Neoproterozoic metamorphic rocks, preserves glacial sediments indicating the presence of major ice sheets. Northern Victoria Land and Tasmania hosted a distinct ice sheet from the one in southern Victoria Land that flowed west-northwestward. The
Sydney Basin The Sydney Basin is an interim Australian bioregion and is both a structural entity and a depositional area, now preserved on the east coast of New South Wales, Australia and with some of its eastern side now subsided beneath the Tasman Sea. ...
of eastern Australia lay at a palaeolatitude of around 60°S to 70°S during the Early and Middle Permian, and its sedimentary successions preserve at least four phases of glaciation throughout this time. Debate exists as to whether 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 North ...
experienced glaciation like the Southern Hemisphere did, with most palaeoclimate models suggesting that ice sheets did exist in Northern Pangaea but that they were very negligible in
volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The def ...
. Diamictites from the Atkan Formation of
Magadan Oblast Magadan Oblast ( rus, Магаданская область, r=Magadanskaya oblast, p=məgɐˈdanskəjə ˈobləsʲtʲ) is a federal subject (an oblast) of Russia. It is geographically located in the Far East region of the country, and is adminis ...
,
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eight ...
have been interpreted as being glacigenic, although recent analyses have challenged this interpretation, suggesting that these diamictites formed during a Capitanian integrlacial interval as a result of volcanogenic
debris flows Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally ...
associated with the formation of the Okhotsk–Taigonos Volcanic Arc.


Causes

The evolution of land plants with the onset of the
Devonian Period The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...
, began a long-term increase in planetary
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well ...
levels. Large
tree ferns The tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae (scaly tree ...
, growing to 20 m high, were secondarily dominant to the large arborescent
lycopods Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching s ...
(30–40 m high) of the
Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous ...
coal forest Coal forests were the vast swathes of wetlands that covered much of the Earth's tropical land areas during the late Carboniferous ( Pennsylvanian) and Permian times.Cleal, C. J. & Thomas, B. A. (2005). "Palaeozoic tropical rainforests and their e ...
s that flourished in equatorial
swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
s stretching from
Appalachia Appalachia () is a cultural region in the Eastern United States that stretches from the Southern Tier of New York State to northern Alabama and Georgia. While the Appalachian Mountains stretch from Belle Isle in Newfoundland and Labrador, C ...
to
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
, and later on the flanks of the
Urals The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through western ...
.
Oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well ...
levels reached up to 35%, and global carbon dioxide got below the 300 parts per million level, possibly as low as 180 ppm during the Kasimovian, which is today associated with glacial periods. This reduction in the
greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...
was coupled with
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity a ...
and
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
(as tree trunks and other vegetation debris) accumulating and being buried in the great Carboniferous
Coal Measures In lithostratigraphy, the coal measures are the coal-bearing part of the Upper Carboniferous System. In the United Kingdom, the Coal Measures Group consists of the Upper Coal Measures Formation, the Middle Coal Measures Formation and the Lower Coa ...
. The reduction of carbon dioxide levels in the atmosphere would be enough to begin the process of changing polar climates, leading to cooler summers which could not melt the previous winter's snow accumulations. The growth in snowfields to 6 m deep would create sufficient pressure to convert the lower levels to ice. Earth's increased planetary
albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
produced by the expanding ice sheets would lead to
positive feedback Positive feedback (exacerbating feedback, self-reinforcing feedback) is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the ...
loops, spreading the ice sheets still further, until the process hit limit. Falling global temperatures would eventually limit plant growth, and the rising levels of oxygen would increase the frequency of fire-storms because damp plant matter could burn. Both these effects return carbon dioxide to the atmosphere, reversing the "snowball" effect and forcing greenhouse warming, with CO2 levels rising to 300 ppm in the following
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
period. Over a longer period the evolution of termites, whose stomachs provided an anoxic environment for methanogenic lignin-digesting bacteria, prevented further burial of carbon, returning carbon to the air as the greenhouse gas
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on ...
. Once these factors brought a halt and a small reversal in the spread of ice sheets, the lower planetary albedo resulting from the fall in size of the glaciated areas would have been enough for warmer summers and winters and thus limit the depth of snowfields in areas from which the glaciers expanded.
Rising sea levels Rising may refer to: * Rising, a stage in baking - see Proofing (baking technique) *Elevation * Short for Uprising, a rebellion Film and TV * "Rising" (''Stargate Atlantis''), the series premiere of the science fiction television program ''Starg ...
produced by global warming drowned the large areas of flatland where previously anoxic swamps assisted in burial and removal of carbon (as
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dead ...
). With a smaller area for deposition of carbon, more carbon dioxide was returned to the atmosphere, further warming the planet. Over the course of the Early and Middle Permian, glacial periods became progressively shorter while warm interglacials became longer, gradually transitioning the world from an icehouse to a greenhouse as the Permian progressed. Obliquity nodes that triggered glacial expansion and increased tropical precipitation before 285.1 Mya became linked to intervals of marine anoxia and increased terrestrial aridification after this point, a turning point signifying the icehouse-greenhouse transition. By 250 Mya, planet Earth had returned to a percentage of oxygen similar to that found today.


Effects

The development of high-frequency, high-amplitude glacioeustasy, which resulted in sea level changes of up to 120 metres between warmer and colder intervals, during the beginning of the LPIA, combined with the increased geographic separation of marine ecoregions and decrease in ocean circulation it caused in conjunction with closure of the Rheic Ocean, has been hypothesised to have been the cause of the Carboniferous-Earliest Permian Biodiversification Event. The rising levels of oxygen during the late Paleozoic icehouse had major effects upon
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
of plants and animals. Higher oxygen concentration (and accompanying higher atmospheric pressure) enabled energetic metabolic processes which encouraged evolution of large land-dwelling arthropods and flight, with the dragonfly-like ''
Meganeura ''Meganeura'' is a genus of extinct insects from the Late Carboniferous (approximately 300 million years ago). They resembled and are related to the present-day dragonflies and damselflies, and were predatory, with their diet mainly consisting of ...
'', an aerial predator, with a wingspan of 60 to 75 cm. The herbivorous stocky-bodied and armoured millipede-like ''
Arthropleura ''Arthropleura'' () is a genus of extinct millipede arthropods that lived in what is now North America and Europe around 345 to 290 million years ago, from the Viséan stage of the lower Carboniferous Period to the Sakmarian stage of the low ...
'' was long, and the semiterrestrial Hibbertopterid
eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is ...
s were perhaps as large, and some
scorpion Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always end ...
s reached . The rising levels of oxygen also led to the evolution of greater fire resistance in vegetation and ultimately to the evolution of flowering plants.


Milankovitch cycles

The LPIA, like the present
Quaternary glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma (million years ago) and is ongoing. Although geologists describe ...
, saw glacial-interglacial cycles governed by Milankovitch cycles acting on timescales of tens of thousands to millions of years. Periods of low obliquity, which decreased annual insolation at the poles, were associated with high moisture flux from low latitudes and glacial expansion at high latitudes, while periods of high obliquity corresponded to warmer, interglacial periods. Milankovitch cycles profound impacts on marine at the height of the LPIA, with high-latitude species being more strongly affected by glacial-interglacial cycles than low-latitude species. Also during this time, unique sedimentary sequences called
cyclothems In geology, cyclothems are alternating stratigraphic sequences of marine and non-marine sediments, sometimes interbedded with coal seams. Historically, the term was defined by the European coal geologists who worked in coal basins formed during ...
were deposited. These were produced by the repeated alterations of marine and nonmarine environments resulting from glacioeustatic rises and falls of sea levels linked to Milankovitch cycles.


See also

*
History of Earth The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologi ...
*
Quaternary glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma (million years ago) and is ongoing. Although geologists describe ...
– the current ice age *
Timeline of glaciation There have been five or six major ice ages in the history of Earth over the past 3 billion years. The Late Cenozoic Ice Age began 34 million years ago, its latest phase being the Quaternary glaciation, in progress since 2.58 million years ago. ...


References


Bibliography

* {{Ice Ages Glaciology Ice ages Carboniferous events Permian events Carboniferous Africa Permian Africa Carboniferous Antarctica Permian Antarctica Carboniferous Australia Permian Australia Carboniferous India Carboniferous South America Permian South America Karoo