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67-598: Based on the magnetic susceptibility of Miocene sedimentary stratigraphic sequences in the Huatugou section in the Qaidam Basin , the MMCO lasted from 17.5 to 14.5 Ma; rocks deposited during this interval have a high magnetic susceptibility due to the production of superparamagnetic and single domain magnetite amidst the warm and humid conditions at the time that defines the MMCO. Estimates derived from Mg/Ca palaeothermometry in

134-516: A superconductive magnet. An alternative is to measure the force change on a strong compact magnet upon insertion of the sample. This system, widely used today, is called the Evans balance . For liquid samples, the susceptibility can be measured from the dependence of the NMR frequency of the sample on its shape or orientation. Another method using NMR techniques measures the magnetic field distortion around

201-643: A deeper mixed layer . The Antarctic Circumpolar Current (ACC) became stronger as westerly wind stress increased and Antarctic sea ice diminished in extent. The global warmth of the MMCO resulted from its elevated atmospheric carbon dioxide concentrations relative to the rest of the Neogene. Boron-based records indicate p CO 2 varied between 300 and 500 ppm during the MMCO. A MMCO p CO 2 estimate of 852 ± 86 ppm has been derived from palaeosols in Railroad Canyon, Idaho . The primary cause of this high p CO 2

268-570: A result of the previous melting of the ice sheet, by increasing the freezing point of the seawater. The current rate of decline of the ice caps has caused many investigations and discoveries on glacier dynamics and their influence on the world's climate. In the early 1950s, scientists and engineers from the US Army began drilling into polar ice caps for geological insight. These studies resulted in "nearly forty years of research experience and achievements in deep polar ice core drillings... and established

335-403: A sample immersed in water inside an MR scanner. This method is highly accurate for diamagnetic materials with susceptibilities similar to water. The magnetic susceptibility of most crystals is not a scalar quantity. Magnetic response M is dependent upon the orientation of the sample and can occur in directions other than that of the applied field H . In these cases, volume susceptibility

402-404: A sample. Polar ice cap A polar ice cap or polar cap is a high- latitude region of a planet , dwarf planet , or natural satellite that is covered in ice . There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land, but only that it must be a body of solid phase matter in

469-495: A senior research scientist at NASA, found that the "rate of warming in the Arctic over the last 20 years is eight times the rate of warming over the last 100 years." In September 2012, sea ice reached its smallest size ever. Journalist John Vidal stated that sea ice is "700,000 sq km below the previous minimum of 4.17m sq km set in 2007". In August 2013, Arctic sea ice extent averaged 6.09m km , which represents 1.13 million km below

536-465: A similar path through Asia and into Australasia. In Japan, Pinus mikii was able to thrive due to warmer temperatures. The coast of southwestern Japan was predominantly populated by thermophilic ostracods. Northern South America possessed tropical evergreen broadleaf forests. The Atacama Desert already existed along the western coast of central South America and graded into temperate xerophytic shrubland and temperate sclerophyll woodland and shrubland to

603-469: A well defined zero-field susceptibility. Volume magnetic susceptibility is measured by the force change felt upon a substance when a magnetic field gradient is applied. Early measurements are made using the Gouy balance where a sample is hung between the poles of an electromagnet. The change in weight when the electromagnet is turned on is proportional to the susceptibility. Today, high-end measurement systems use

670-420: Is a dimensionless proportionality constant that indicates the degree of magnetization of a material in response to an applied magnetic field. A related term is magnetizability , the proportion between magnetic moment and magnetic flux density . A closely related parameter is the permeability , which expresses the total magnetization of material and volume. The volume magnetic susceptibility , represented by

737-411: Is a tensor derived from partial derivatives of components of M with respect to components of H . When the coercivity of the material parallel to an applied field is the smaller of the two, the differential susceptibility is a function of the applied field and self interactions, such as the magnetic anisotropy . When the material is not saturated , the effect will be nonlinear and dependent upon

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804-421: Is applied perpendicular to the detection direction (called the "transverse susceptibility" regardless of the frequency), the effect has a peak at the ferromagnetic resonance frequency of the material with a given static applied field. Currently, this effect is called the microwave permeability or network ferromagnetic resonance in the literature. These results are sensitive to the domain wall configuration of

871-725: Is called the Monterey Carbon Excursion, which is globally recorded but mainly in the Circum-Pacific Belt. The Monterey Excursion seems to envelop the MMCO, meaning this carbon excursion started just before the climatic optimum and it ended just after it. However, recent work has challenged and contradicted the Monterey Hypothesis on the basis of evidence showing that the MMCO occurred during an interval of low organic carbon burial, likely due to enhanced bacterial decomposition of organic matter that recycled carbon back into

938-563: Is covered by floating pack ice ( sea ice ) over the Arctic Ocean . Portions of the ice that do not melt seasonally can get very thick, up to 3–4 meters thick over large areas, with ridges up to 20 meters thick. One-year ice is usually about 1 meter thick. The area covered by sea ice ranges between 9 and 12 million km . In addition, the Greenland ice sheet covers about 1.71 million km and contains about 2.6 million km of ice. When

1005-424: Is defined as I = d e f μ 0 M . {\displaystyle \mathbf {I} {\stackrel {\mathrm {def} }{=}}\mu _{0}\mathbf {M} .} This allows an alternative description of all magnetization phenomena in terms of the quantities I and B , as opposed to the commonly used M and H . There are two other measures of susceptibility,

1072-409: Is defined as a tensor : M i = H j χ i j {\displaystyle M_{i}=H_{j}\chi _{ij}} where i and j refer to the directions (e.g., of the x and y Cartesian coordinates ) of the applied field and magnetization, respectively. The tensor is thus degree 2 (second order), dimension (3,3) describing the component of magnetization in

1139-498: Is generally accepted to be elevated volcanic activity. Hydrothermal alteration by magmatic dikes and sills of sediments rich in organic carbon further contributed to rising p CO 2 . The activity of the Columbia River Basalt Group (CRBG), a large igneous province in the northwestern United States that emitted 95% of its contents between 16.7 and 15.9 Ma, is believed to be the dominant geological event responsible for

1206-672: Is the vacuum permeability (see table of physical constants ), and (1 + χ v ) is the relative permeability of the material. Thus the volume magnetic susceptibility χ v and the magnetic permeability μ are related by the following formula: μ = d e f μ 0 ( 1 + χ v ) . {\displaystyle \mu {\stackrel {\mathrm {def} }{=}}\mu _{0}\left(1+\chi _{\text{v}}\right).} Sometimes an auxiliary quantity called intensity of magnetization I (also referred to as magnetic polarisation J ) and with unit teslas ,

1273-650: Is therefore a dimensionless quantity . Using SI units , the magnetic induction B is related to H by the relationship B   =   μ 0 ( H + M )   = linear [   μ 0 ( 1 + χ v ) H   =   μ H ] {\displaystyle \mathbf {B} \ =\ \mu _{0}\left(\mathbf {H} +\mathbf {M} \right)\ {\overset {\text{linear}}{=}}[\ \mu _{0}\left(1+\chi _{\text{v}}\right)\mathbf {H} \ =\ \mu \mathbf {H} ]} where μ 0

1340-502: The Arctic has lost an average of 20,800 square miles (53,900 square kilometres) of sea ice per year while the Antarctic has gained an average of 7,300 square miles (18,900 km ) of sea ice per year. At the same time, the Arctic has been losing around 50 cubic kilometres (gigatons) of land ice per year, almost entirely from Greenland's 2.6 million gigaton sheet. On 19 September 2014, for

1407-683: The Fermi surface of the material. An analogue non-linear relation between magnetization and magnetic field happens for antiferromagnetic materials . When the magnetic susceptibility is measured in response to an AC magnetic field (i.e. a magnetic field that varies sinusoidally ), this is called AC susceptibility . AC susceptibility (and the closely related "AC permeability") are complex number quantities, and various phenomena, such as resonance, can be seen in AC susceptibility that cannot occur in constant-field ( DC ) susceptibility. In particular, when an AC field

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1474-1057: The International System of Quantities (ISQ) upon which the SI is based. However, many tables of magnetic susceptibility give the values of the corresponding quantities of the CGS system (more specifically CGS-EMU , short for electromagnetic units, or Gaussian-CGS ; both are the same in this context). The quantities characterizing the permeability of free space for each system have different defining equations: B CGS = H CGS + 4 π M CGS = ( 1 + 4 π χ v CGS ) H CGS . {\displaystyle \mathbf {B} ^{\text{CGS}}=\mathbf {H} ^{\text{CGS}}+4\pi \mathbf {M} ^{\text{CGS}}=\left(1+4\pi \chi _{\text{v}}^{\text{CGS}}\right)\mathbf {H} ^{\text{CGS}}.} The respective CGS susceptibilities are multiplied by 4 π to give

1541-425: The benthic foraminifer Oridorsalis umbonatus suggest the onset of the MMCO occurred at 16.9 Ma, peak warmth at 15.3 Ma, and the end of the MMCO at 13.8 Ma. Global mean surface temperatures during the MMCO were approximately 18.4 °C, about 3 °C warmer than today and 4 °C warmer than preindustrial. The latitudinal zone of tropical climate was significantly extended. The latitudinal climate gradient

1608-481: The domain wall configuration of the material. Several experimental techniques allow for the measurement of the electronic properties of a material. An important effect in metals under strong magnetic fields, is the oscillation of the differential susceptibility as function of ⁠ 1 / H ⁠ . This behaviour is known as the De Haas–Van Alphen effect and relates the period of the susceptibility with

1675-468: The fresh water on Earth is contained in this ice sheet. Data from the National Snow and Ice Data Center shows that the sea ice coverage of Antarctica has a slightly positive trend over the last three decades (1979–2009). Over the past several decades, Earth's polar ice caps have gained significant attention because of the alarming decrease in land and sea ice. NASA reports that since the late 1970s,

1742-487: The i th direction from the external field applied in the j th direction. In ferromagnetic crystals, the relationship between M and H is not linear. To accommodate this, a more general definition of differential susceptibility is used: χ i j d = ∂ M i ∂ H j {\displaystyle \chi _{ij}^{d}={\frac {\partial M_{i}}{\partial H_{j}}}} where χ ij

1809-460: The magnetic susceptibility (from Latin susceptibilis  'receptive'; denoted χ , chi ) is a measure of how much a material will become magnetized in an applied magnetic field . It is the ratio of magnetization M ( magnetic moment per unit volume ) to the applied magnetic field intensity H . This allows a simple classification, into two categories, of most materials' responses to an applied magnetic field: an alignment with

1876-747: The molar magnetic susceptibility ( χ m ) with unit m /mol, and the mass magnetic susceptibility ( χ ρ ) with unit m /kg that are defined below, where ρ is the density with unit kg/m and M is molar mass with unit kg/mol: χ ρ = χ v ρ ; χ m = M χ ρ = M ρ χ v . {\displaystyle {\begin{aligned}\chi _{\rho }&={\frac {\chi _{\text{v}}}{\rho }};\\\chi _{\text{m}}&=M\chi _{\rho }={\frac {M}{\rho }}\chi _{\text{v}}.\end{aligned}}} The definitions above are according to

1943-511: The polar region . This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that are over land, and cover less than 50,000 km : larger bodies are referred to as ice sheets . The composition of the ice will vary. For example, Earth's polar caps are mainly water ice, whereas Mars 's polar ice caps are a mixture of solid carbon dioxide and water ice. Polar ice caps form because high-latitude regions receive less energy in

2010-593: The 1981–2010 average for that month. In addition to Earth, the planet Mars also has polar ice caps. They consist of primarily water-ice with a few percent dust. Frozen carbon dioxide makes up a small permanent portion of the Planum Australe or the South Polar Layered Deposits. In both hemispheres a seasonal carbon dioxide frost deposits in the winter and sublimates during the spring. Data collected in 2001 from NASA missions to Mars show that

2077-511: The Arctic. Northern North America was dominated by cool-temperate forests. Western North America was mostly composed of warm-temperate evergeen broadleaf and mixed forest. In spite of the climatic changes, the niches of Oregonian equids were unchanged throughout the MMCO. What is now the Mojave Desert was a grassland dominated by C 3 grasses during the MMCO. Central America had tropical vegetation, as it does today. Terrestrial mammals in

Middle Miocene Climatic Optimum - Misplaced Pages Continue

2144-726: The CGS molar susceptibility with unit cm /mol or emu/mol⋅Oe . If χ is positive, a material can be paramagnetic . In this case, the magnetic field in the material is strengthened by the induced magnetization. Alternatively, if χ is negative, the material is diamagnetic . In this case, the magnetic field in the material is weakened by the induced magnetization. Generally, nonmagnetic materials are said to be para- or diamagnetic because they do not possess permanent magnetization without external magnetic field. Ferromagnetic , ferrimagnetic , or antiferromagnetic materials possess permanent magnetization even without external magnetic field and do not have

2211-449: The CGS volume magnetic susceptibility of water at 20 °C is 7.19 × 10 , which is 9.04 × 10 using the SI convention, both quantities being dimensionless. Whereas for most electromagnetic quantities, which system of quantities it belongs to can be disambiguated by incompatibility of their units, this is not true for the susceptibility quantities. In physics it is common to see CGS mass susceptibility with unit cm /g or emu/g⋅Oe , and

2278-474: The CRC. In Earth science , magnetism is a useful parameter to describe and analyze rocks. Additionally, the anisotropy of magnetic susceptibility (AMS) within a sample determines parameters as directions of paleocurrents , maturity of paleosol , flow direction of magma injection, tectonic strain, etc. It is a non-destructive tool which quantifies the average alignment and orientation of magnetic particles within

2345-550: The Central Paratethys. Because of the dense, humid forests covering central eastern France and northern Germany, the species richness of these areas was high and mammals were dominated by small taxa, while the more arid Iberian Peninsula had a lower species richness and a relative absence of medium-sized mammals. In Poland, the Mid-Polish Lignite Seam was formed due to an abundance of peat-forming vegetation. Along

2412-605: The EAIS remained relatively thick. Additionally, Antarctica's polar ice sheets exhibited high variability and instability throughout this warm period. Modelling of ocean circulation shows that the Atlantic Meridional Overturning Circulation (AMOC) was strengthened by the greater inflow of waters from the Pacific and Indian Oceans due to more open Panama and Tethys Seaways . This stronger AMOC in turn resulted in

2479-436: The MMCO as an analogue for what Earth's future climate will look like. Arguably, it is the best of all possible analogues; the p CO 2 of the cooler Pliocene has already been exceeded, while the warmer Eocene had global temperatures and carbon dioxide levels so high that reaching them would require scenarios that are no longer considered realistic or likely to occur. Magnetic susceptibility In electromagnetism ,

2546-482: The MMCO. The MMCO's temperature estimates of 3–4 °C above the preindustrial mean are similar to those projected in the future by mid-range forecasts of anthropogenic global warming conducted by the Intergovernmental Panel on Climate Change (IPCC). Estimates of future p CO 2 are also remarkably similar to those derived for the MMCO. Because of these many similarities, many palaeoclimatologists use

2613-545: The MMCO. Dense, humid rainforests covered much of France , Switzerland , and northern Germany , while southern and central Spain were arid and contained open environments. In the North Alpine Foreland Basin (NAFB), hydrological cycling intensified during the MMCO. The Austrian locality of Stetten had a mean winter temperature of 9.6–13.3 °C and a mean summer temperature of 24.7–27.9 °C, contrasting with −1.4 °C and 19.9 °C respectively in

2680-776: The MMCO. The CRBG has been estimated to have added 4090–5670 Pg of carbon into the atmosphere in total, 3000–4000 Pg of which was discharged during the Grande Ronde Basalt eruptions, explaining much of the MMCO's anomalous warmth. Carbon dioxide was released both directly from volcanic activity as well as by cryptic degassing from intrusive magmatic sills that liberated the greenhouse gas from existing sediments. However, CRBG activity and cryptic degassing do not sufficiently explain warming before 16.3 Ma. Enhanced tectonic activity led to increased volcanic degassing at plate margins, causing high background warmth and complementing CRBG activity in driving temperatures upwards. Albedo decrease from

2747-691: The Miocene; temperatures here may have been kept low by an uplift of the Appalachian Mountains . Northern South America developed increased seasonality in its precipitation patterns as a consequence of the ITCZ's northward migration during the MMCO. The Bolivian Altiplano had a MAT of 21.5–21.7 ± 2.1 °C, in stark contrast to its present MAT of 8–9 °C, while its MMCO precipitation patterns were identical to those of today. The Cape Peninsula in South Africa

Middle Miocene Climatic Optimum - Misplaced Pages Continue

2814-480: The applied field, the magnetization of the material adds its own magnetic field, causing the field lines to concentrate in paramagnetism, or be excluded in diamagnetism. Quantitative measures of the magnetic susceptibility also provide insights into the structure of materials, providing insight into bonding and energy levels . Furthermore, it is widely used in geology for paleomagnetic studies and structural geology . The magnetizability of materials comes from

2881-424: The atomic-level magnetic properties of the particles of which they are made. Usually, this is dominated by the magnetic moments of electrons . Electrons are present in all materials, but without any external magnetic field, the magnetic moments of the electrons are usually either paired up or random so that the overall magnetism is zero (the exception to this usual case is ferromagnetism ). The fundamental reasons why

2948-712: The corresponding ISQ quantities (often referred to as SI quantities) with the same units: χ m SI = 4 π χ m CGS {\displaystyle \chi _{\text{m}}^{\text{SI}}=4\pi \chi _{\text{m}}^{\text{CGS}}} χ ρ SI = 4 π χ ρ CGS {\displaystyle \chi _{\text{ρ}}^{\text{SI}}=4\pi \chi _{\text{ρ}}^{\text{CGS}}} χ v SI = 4 π χ v CGS {\displaystyle \chi _{\text{v}}^{\text{SI}}=4\pi \chi _{\text{v}}^{\text{CGS}}} For example,

3015-402: The data from the National Snow and Ice Data Center. Still, between these same years, the overall average ice coverage appears to have declined from 8 million km to 5 million km . Earth's south polar land mass, Antarctica , is covered by the Antarctic ice sheet . It covers an area of about 14.6 million km and contains between 25 and 30 million km of ice. Around 70% of

3082-469: The first time since 1979, Antarctic sea ice extent exceeded 7.72 million square miles (20 million square kilometres), according to the National Snow and Ice Data Center . The ice extent stayed above this benchmark extent for several days. The average maximum extent between 1981 and 2010 was 7.23 million square miles (18.72 million square kilometres). The single-day maximum extent in 2014

3149-484: The form of solar radiation from the Sun than equatorial regions, resulting in lower surface temperatures. Earth's polar caps have changed dramatically over the last 12,000 years. Seasonal variations of the ice caps takes place due to varied solar energy absorption as the planet or moon revolves around the Sun. Additionally, in geologic time scales, the ice caps may grow or shrink due to climate change. Earth's North Pole

3216-411: The fundamental drilling technology for retrieving deep ice cores for climatologic archives." Polar ice caps have been used to track current climate patterns but also patterns over the past several thousands years from the traces of CO 2 and CH 4 found trapped in the ice. In the past decade, polar ice caps have shown their most rapid decline in size with no true sign of recovery. Josefino Comiso,

3283-596: The high temperatures of the Middle Miocene . The West African Monsoon strengthened. The strengthening of West African offshore winds and enhancement of continental weathering in North Africa caused oxygen minimum zones to expand in the Atlantic off the coast of West Africa. The world of the MMCO was heavily forested; trees grew across the Arctic and even in parts of Antarctica. Tundras and forest tundras were absent from

3350-467: The ice breaks off (calves) it forms icebergs scattered around the northern Atlantic. According to the National Snow and Ice Data Center , "since 1979, winter Arctic ice extent has decreased about 4.2 percent per decade". Both 2008 and 2009 had a minimum Arctic sea ice extent somewhat above that of 2007. At other times of the year the ice extent is still sometimes near the 1979–2000 average, as in April 2010, by

3417-458: The magnetic field, χ > 0 , called paramagnetism , or an alignment against the field, χ < 0 , called diamagnetism . Magnetic susceptibility indicates whether a material is attracted into or repelled out of a magnetic field. Paramagnetic materials align with the applied field and are attracted to regions of greater magnetic field. Diamagnetic materials are anti-aligned and are pushed away, toward regions of lower magnetic fields. On top of

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3484-409: The magnetic moments of the electrons line up or do not are very complex and cannot be explained by classical physics . However, a useful simplification is to measure the magnetic susceptibility of a material and apply the macroscopic form of Maxwell's equations . This allows classical physics to make useful predictions while avoiding the underlying quantum mechanical details. Magnetic susceptibility

3551-399: The material and eddy currents . In terms of ferromagnetic resonance, the effect of an AC-field applied along the direction of the magnetization is called parallel pumping . The CRC Handbook of Chemistry and Physics has one of the few published magnetic susceptibility tables. The data are listed as CGS quantities. The molar susceptibility of several elements and compounds are listed in

3618-523: The minimal cold months temperature (mCMT) was at least 8.0 °C and the minimal warm months temperature (mWMT) was about 18.3 °C, with an overall MAT no cooler than 17.4 °C. Central Europe's annual precipitation range was 1050–1600 mm, based on data from Hevlín Quarry in the Czech Republic . Climatic data from Poland and Bulgaria suggest a minimal latitudinal temperature gradient in Europe during

3685-467: The ocean-atmosphere system, and that this organic carbon burial nadir contributed to the sustained warmth of the MMCO. Climate modelling has shown that there remain as-of-yet unknown forcing and feedback mechanisms that had to have existed to account for the observed rise in temperature during the MMCO, as the amount of carbon dioxide known to have been in the atmosphere during the MMCO along with other known boundary conditions are insufficient to explain

3752-470: The present. In the Paratethys, marine biodiversity peaked at the culmination of the MMCO. The MMCO may have favoured the spread of pongines into Asia by creating continuous stretches of subtropical forest that enabled the migration of these apes from Africa into Eurasia. There was a simultaneous dispersal of rhizomyine and ctenodactyline rodents along this same corridor. A dispersal of Uvaria followed

3819-721: The present; precipitation amounts at this site were 9–24 mm in winter and 204–236 mm in summer. Unusually, the bottom waters of the Vienna Basin show a marked cooling during the MMCO. The Northern Hemisphere summer location of the Intertropical Convergence Zone (ITCZ) shifted northward; because the ITCZ is the zone of maximum monsoon rainfall, the precipitation brought by the East Asian Summer Monsoon (EASM) increased over southern China while simultaneously declining over Indochina. The Tibetan Plateau

3886-534: The reduction in Earth's surface area covered by deserts and the expansion of forests was an important positive feedback enhancing the warmth of the MMCO. The nature and magnitude of organic carbon burial during the MMCO is controversial. The orthodox hypothesis holds that the increase in organic carbon burial on lands submerged by rising sea levels resultant from the increased warmth were an important negative feedback inhibiting further warming. This positive carbon excursion

3953-462: The south. In eastern South America south of 35° S, warm-temperate evergreen broadleaf and mixed forest predominated, alongside temperate grassland. The MMCO played a major role in the partitioning and diversification of South America's land mammal faunas. In Africa, rapid speciation in Bicyclus representing the continent's largest radiation of satyrine butterflies occurred amidst the climatic changes of

4020-531: The southern residual ice cap undergoes sublimation inter-annually. The most widely accepted explanation is that fluctuations in the planet's orbit are causing the changes. On 29 April 2015, NASA stated that its New Horizons missions had discovered a feature thought to be a polar ice cap on the dwarf planet Pluto . The probe's flyby of Pluto in July 2015 allowed the Alice ultraviolet imaging spectrometer to confirm that

4087-481: The symbol χ v (often simply χ , sometimes χ m  – magnetic, to distinguish from the electric susceptibility ), is defined in the International System of Units  – in other systems there may be additional constants – by the following relationship: M = linear χ v H . {\displaystyle \mathbf {M} {\overset {\text{linear}}{=}}\chi _{\text{v}}\mathbf {H} .} Here, χ v

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4154-750: The tectonically active region of western North America experienced a surge in species originations. In Europe, there was a northward expansion of thermophilic plants during the MMCO. Along the northwestern coast of the Central Paratethys , mixed mesophytic forest vegetation predominated. At the Stetten locality, spruces and firs increased in abundance during transgressive phases of precessionally forced transgressive-regressive cycles, while marshes , many of them saline , dominated by Cyperaceae and swamps dominated by Taxodiaceae prevailed during sea level lowstands. Offshore, coral reefs were able to develop in

4221-411: The western margin of the Central Paratethys, primate diversity exploded, likely because of the unique mosaic of different habitats it hosted. The genus Procervulus was able to diversify its dietary habits as a result of the MMCO's effects on vegetation and ecosystem structure in Europe. Europe also contained an abundance of ectothermic vertebrates due to its much warmer climate in the MMCO compared to

4288-471: Was about 0.3 °C per degree of latitude. During orbital eccentricity maxima, which corresponded to warm phases, the ocean's lysocline shoaled by approximately 500 metres. The Arctic was ice free and warm enough to host permanent forest cover across much of its extent. Iceland had a humid and subtropical climate. The mean annual temperature (MAT) of the United Kingdom was 16.9 °C. In Central Europe ,

4355-546: Was overall wetter and warmer. Overall, Western North America north of 40° N was wetter than south of 40° N. The interior Pacific Northwest experienced a dramatic increase in precipitation during the MMCO around 15.1 Ma. In contrast, the Mojave region of western North America exhibited a drying trend. Along the New Jersey shelf, the MMCO did not result in any discernable climatic signal relative to earlier or later climatic intervals of

4422-465: Was reached on 20 Sep, according to NSIDC data, when the sea ice covered 7.78 million square miles (20.14 million square kilometres). The 2014 five-day average maximum was reached on 22 Sep, when sea ice covered 7.76 million square miles (20.11 million square kilometres), according to NSIDC . This increase could be due to the reduction in the salinity of the Antarctic Ocean as

4489-406: Was significantly warmer than today, and its environment fluctuated between open riparian forest and swampland. In Antarctica , average summer temperatures were about 10 °C. The East Antarctic Ice Sheet (EAIS) was severely reduced in area, and it may have occupied as little as 25% of its present volume. However, despite its diminished size and its retreat away from the coastline of Antarctica,

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