Links between Fluctuations in Glaciation and World's Biomes during the Quaternary - Essay Example

Running Head: THE LINKS BETWEEN FLUCTUATIONS IN GLACIATION AND THE WORLD'S BIOMES DURING THE QUATERNARY The Links between Fluctuations in Glaciation and the World's Biomes during the Quaternary Name Tutor Date The Links between Fluctuations in Glaciation and the World's Biomes during the Quaternary Emergence of the Current Climate The change from the warm greenhouse climate to the very cold climate of the quaternary was for the most part slow but sure. For the past 2.6 million years ago, elevated moisture transportation to higher latitudes owing to the changes within continental positions as well as mountain climbing together with evolution of more complicated ecosystems led to the decrease of carbon dioxide levels within the atmosphere/environment (Pollard, 2009). During this era, changes in the characteristics of the orbit of the earth which establishes the manner in which sunlight hits the earth had insignificant effects when compared to what followed thereafter. The changes during the tertiary period include the orbital forcing which were not strong enough to supersede the high atmospheric carbon concentrations and establish movement the positive feedbacks that enable glaciers at the pole to develop into mid latitudes (Naish, 2009). Orbital Forcings Basically, there are three aspects of the earth’s orbital patterns that give the best available hypothesis regarding what controls the strength as well as seasonability of the sunlight that hits and controls the level of the ice found on the surface of the planet (Pollard, 2009). Eccentricity When a bigger object is orbited by a smaller object, basically it does not move within an ideal circle. This means that there will be points when the object will be much nearer or farther from each other. To be precise, eccentricity refers to the measure of how much an orbital pattern goes away form an ideal circle. At present, the eccentricity of the earth is about 0.017 implying that the earth is about 3.2 million miles nearer to the sun at the perihelion (perihelion is the point nearest to the sun) than is at the aphelion (aphelion is the point furthest away from the sun). Periodic fluctuations within eccentricity are as a result of unevenness within the gravitational effects of both Jupiter and Saturn). The two common overview s regarding the effect of eccentricity on the climate of the earth, provided the present continental orientation include: the first one is that things become warmer when the perihelion take place during the time of the boreal summer solstice and also when this solstice drops during aphelion. The second overview is that basically more eccentricity although not always keeps up a correspondence to more glaciation (Naish, 2009). Obliquity The orbit of the earth has an axial tilt. This implies that the equator is not basically in line with the earth’s plane around the sun. At present, the axial tilt of the earth is approximately 23.44 degrees and also oscillates between 22.1 and 24.5 degrees for a period of 41, 000 years. As a result, the axial tilt leads to the development of the seasons. Consequently, less obliquity implies decreased variation within the intensity of the solar at high latitudes. The less variation results into making conditions more favorable for the development of glaciers at the poles (Pollard, 2009). Precession This is the third orbital forcing. During the rotation of the earth, oceans apply pressure on the solid surface. Both the ebb and flow of the tides lead to this pressure into being sporadically stronger or weaker at diverse positions on the earth. The variations within the ebb and flow are as a result of changes within the virtual points of the sun and moon. This together with the verity that earth has a bulge at the equator since earth is not an ideal sphere causes the direction of rotational axis to oscillate on a period of approximately 26, 000 years, a observable fact referred to as precession. In case the axis is pointed at the sun for the period of perihelion, consequently one hemisphere will have more extreme seasons as compared to the other. Extreme summers within the northern hemisphere which result into continental orientation lead into the spreading out of tree cover there and hence trees absorb more incoming radiation as compared to the grassland. Consequently, there is warming glacial retreat and hence additional expansion of the forest and increased warming (Salzmann, 2008). El Nino-Southern Oscillation (ENSO): Climate Linchpin About 4 million years ago, the panama seaway got closed and this changed the ocean’s patterns circulation. About 2 million years ago, the ocean sub surface had cooled such that it became possible for an outpouring of cool water within the eastern tropical pacific to break through the planet-wide layer of warm surface water as well as set up a cold tongue. What was to become El Nino-Southern Oscillation (ENSO) developed and the occurrence of this had two key outcomes: The first outcome is that it led to the development of a temperature gradient between the eastern and western tropical Pacific. This is normally at its most powerful point when the cold tongue projects to the surface; the La Nina phase of the ENSO cycle. This led into an east-west pressure gradient that made trade winds more powerful. Normally, trade winds blow westward across the pacific. Strengthened trade winds worked to sustain the pressure gradient which is responsible for their presence. Furthermore, the pressure gradient also developed deviation within the upper atmosphere that led into a movement of the mid-latitude storm tracks nearer to the poles enabling a rise in wintertime moisture transfer to elevated latitudes and a moisture sequestration within polar glaciers. This led into: A rise within planetary albedo or the surface’s capacity to reflect light. This caused more cooling. Moreover, it led into a rise within the height of the ice masses, which decreased their propensity to the melting of the surface. The East Antarctic ice sheet for instance, is further above sea level as compared to the west Antarctic and has demonstrated to be very resistant to the fluctuations of the global climate. More forceful ice implies that the high latitudes possess high albedo for more of the year, which implies more cooling (Pollard, 2009). The second outcome was the infiltration of cool and more nutrient rich water coming from the depths of the ocean raised the level of phytoplankton blooms within that segment of the ocean. As phytoplankton concluded their life cycles, the dropped to the bottom of the ocean as well as sequestered carbon within their bodies. This further decreased the concentrations of carbon dioxide and putting emphasis on the cooling trend. By 1.8 million years ago, which was the beginning of the Pleistocene period, thing had cooled to the level that the planet was waxing and waning between glacial as well as interglacial cycles on an era 41.000 years, according to the oscillations of obliquity cycle. These glacial cycles went on until around 1.17 million years ago, when additional escalation of the cold tongue within the eastern pacific led to the development of the contemporary walker circulation. This led to even more pole ward moisture transportation and armored the positive feedbacks as illustrated above. This strengthened the development of glacial and hence led to the development of the current 100, 000 year glacial cycle (Salzmann, 2008). Aspects of modern glacial-integral cycles Whereas there are still discussions about the comparative significance of the feedbacks that result into glaciation in addition to deglaciation, there are three main aspects that have been theorized consist of: Glacial carbon dioxide storage/release According to this theory, as glaciers expand, they get both forests and grasslands covered and this sequesters biomass which is mainly plant tissue and lowering latent atmospheric concentrations of the carbon. After the glaciers reach some point, nevertheless their bases start melting and streams having carbon are hence discharged. Consequently, this facilitates the escapement of the contained carbon. This assists in increasing atmospheric levels as well as the temperature of the earth more so if the discharges take place at the setting up of orbital conditions more favorable to warming (Stone, 2008). Northern hemisphere discharge events and southern ocean carbon dioxide In this hypothesis, as the cooling of the earth goes on, oceans absorb and store carbon dioxide within their depths. Basically, when orbital conditions that are favorable to warming start, more so if they take place together with the carbon escape as illustrated above, the northern hemisphere ice sheets begin melting and hence release fresh water into the Atlantic, at times at a disastrous pace. Swift releases trigger the balance between salt and fresh water that makes the Atlantic Meridional Overturning Circulation (AMOC) functioning. As a result, a close down within the AMOC results to an disruption of the ocean currents that take warm air masses to the high latitudes of the Northern Hemisphere but also leads into warming within the South Atlantic and more outpouring around Antarctica. Fundamentally, more Southern Ocean outpouring implies more out-gassing of stored oceanic carbon dioxide, which contributes to more warming, additional ice releases incidences, more carbon dioxide as well warming (Solomon, 2007). Re-growth and Carbon Sequestration In this hypothesis, as glaciers retreat, vegetation comes back and hence takes out atmospheric carbon. Finally, the quantities of carbon are decreased to a level that, given the exact orbital circumstances, glaciation goes back and hence the cycle starts again. For the past million years, the modern glacial-interglacial cycle has attributed an estimated nine degree Fahrenheit global temperature fluctuation in addition to a corresponding 80-120 ppm carbon dioxide fluctuation. In this case, the glacial-interglacial carbon dioxide range is between 180 and 300 parts per million (Stone, 2008). Carbon dioxide level According to the latest studies, for about 2.6 years ago, the level of carbon dioxides concentrations within the atmosphere reached between 330 and 400 ppm. During this period, global temperature were between 2-3 higher than now and also sea levels were higher than now by about 10-25 meters, meaning that global ice volume was extremely low compared to today. There were higher fluctuations within ice cover on Greenland as well as West Antarctica and during the warm intermissions those area were almost certainly fundamentally free of ice. Some ice could also have been lost from some parts of East Antarctica during warm intermissions. Coniferous forests reinstated tundra within the high latitude of the Northern Hemisphere and also Arctic Ocean could have been seasonally free of sea-ice (Salzmann, 2008). Conclusion Whereas the past climatic changes can be connected to geological incidence, it is not possible to relay the warming of earth from 1970 to anything identifiable as having geological cause for instance volcanic activity, continental dislocation, or changes within the energy gotten from the sun. The latest warming is accompanied by a rise in carbon dioxide and a reduction in Arctic se ice. These two are founded on physical theory and geological analogues and hence are anticipated to warm the climate. Large part of the modern rise in carbon dioxide results from burning fossil fuels, with some contribution from cement manufacture as well as from deforestation. Generally, human activities have released over 500 billion tones of carbon to the atmosphere from around 1750, whereby 65% of this has resulted from burning of fossil fuels. Some of the carbon contribution to the atmosphere comes from volcanoes. However, carbon from volcanoes is equivalent to just about one percent of what human activities add yearly and is not contributing to a net increase (Solomon, 2007). References Naish, T. (2009). Obliquity-paced Pliocene West Antarctic ice sheet oscillations. Nature. Vol. , 322-328. Stone, E.J., (2008). Late Pliocene Greenland glaciation controlled by a decline in atmospheric CO2 levels. Nature. Vol. 454 (7208), 1102-1105. Pollard, D. (2009). Modeling West Antarctic ice sheet growth and collapse through the past five million years. Nature. Vol. 458, 329-332. Salzmann, U. (2008). A new global biome reconstruction and data-model comparison for the Middle Pliocene. Global Ecology and Biogeography. Vol. 17(3), 432-447. Solomon, S. (2007). Climate change 2007: The physical science basis. Contribution of Working Group I to the 4th Assessment Report of the IPCC. Cambridge: Cambridge University Press. Read More

As a result, the axial tilt leads to the development of the seasons. Consequently, less obliquity implies decreased variation within the intensity of the solar at high latitudes. The less variation results into making conditions more favorable for the development of glaciers at the poles (Pollard, 2009). Precession This is the third orbital forcing. During the rotation of the earth, oceans apply pressure on the solid surface. Both the ebb and flow of the tides lead to this pressure into being sporadically stronger or weaker at diverse positions on the earth.

The variations within the ebb and flow are as a result of changes within the virtual points of the sun and moon. This together with the verity that earth has a bulge at the equator since earth is not an ideal sphere causes the direction of rotational axis to oscillate on a period of approximately 26, 000 years, a observable fact referred to as precession. In case the axis is pointed at the sun for the period of perihelion, consequently one hemisphere will have more extreme seasons as compared to the other.

Extreme summers within the northern hemisphere which result into continental orientation lead into the spreading out of tree cover there and hence trees absorb more incoming radiation as compared to the grassland. Consequently, there is warming glacial retreat and hence additional expansion of the forest and increased warming (Salzmann, 2008). El Nino-Southern Oscillation (ENSO): Climate Linchpin About 4 million years ago, the panama seaway got closed and this changed the ocean’s patterns circulation.

About 2 million years ago, the ocean sub surface had cooled such that it became possible for an outpouring of cool water within the eastern tropical pacific to break through the planet-wide layer of warm surface water as well as set up a cold tongue. What was to become El Nino-Southern Oscillation (ENSO) developed and the occurrence of this had two key outcomes: The first outcome is that it led to the development of a temperature gradient between the eastern and western tropical Pacific. This is normally at its most powerful point when the cold tongue projects to the surface; the La Nina phase of the ENSO cycle.

This led into an east-west pressure gradient that made trade winds more powerful. Normally, trade winds blow westward across the pacific. Strengthened trade winds worked to sustain the pressure gradient which is responsible for their presence. Furthermore, the pressure gradient also developed deviation within the upper atmosphere that led into a movement of the mid-latitude storm tracks nearer to the poles enabling a rise in wintertime moisture transfer to elevated latitudes and a moisture sequestration within polar glaciers.

This led into: A rise within planetary albedo or the surface’s capacity to reflect light. This caused more cooling. Moreover, it led into a rise within the height of the ice masses, which decreased their propensity to the melting of the surface. The East Antarctic ice sheet for instance, is further above sea level as compared to the west Antarctic and has demonstrated to be very resistant to the fluctuations of the global climate. More forceful ice implies that the high latitudes possess high albedo for more of the year, which implies more cooling (Pollard, 2009).

The second outcome was the infiltration of cool and more nutrient rich water coming from the depths of the ocean raised the level of phytoplankton blooms within that segment of the ocean. As phytoplankton concluded their life cycles, the dropped to the bottom of the ocean as well as sequestered carbon within their bodies. This further decreased the concentrations of carbon dioxide and putting emphasis on the cooling trend. By 1.8 million years ago, which was the beginning of the Pleistocene period, thing had cooled to the level that the planet was waxing and waning between glacial as well as interglacial cycles on an era 41.

000 years, according to the oscillations of obliquity cycle.

Read More