The Lively Earth: Important Features Make the Earth Unique

EASC 2112 Earth System The lively Earth: important features make the Earth unique Name: Leung Ho Nam, Banson UID: 2011712579 Introduction: The Earth is one of the eight planets in the solar system. The planet Earth is emphasized as â€Å"the rare Earth† in numerous literatures because of its unique physical conditions and the complicated interactions among all biotic and abiotic systems. Isotope dating indicates the earth was formed approximately from 4. 53 to 4. 568 Ga, according to isotope used (Allegre et. al. , 1995).Despite the precise formation time of the Earth, there is no exact planet formation model that is generally accepted except the minimum mass solar nebula model, MMSN (Canup, 2008). The MMSN model suggested the planetary accretion of the Earth and other terrestrial planets begins with a disc of hydrogen abundant gas and dust, circulating around the sun. Following by a series of collision, small particles combine and collapse repeatedly. The runaway growth slows down until reaching a certain mass (Canup, 2008). The formation process is crucial to the evolution of the Earth because it determines the source of materials which the Earth contains.The formation of the Earth, indeed, is not specific enough to comprise â€Å"the rare Earth† because all solar planets were grown within a circumsolar disc of gas and dust suggested by Canuo (2008). When we look at the solar system from the outer space, the Earth is probably the only shiny blue planet because of water surface reflection. 70 percent of the Earth surface is covered by the ocean. There is approximately 1. 4 billion km2 of liquid water by mass on Earth (Oak & Kanae, 2006). The existence of permanent liquid water responsible to create a mild temperature and a stable environment.Liquid water is an important element implicates the emergence and evolution of life on Earth after a few million years from the latest collision (Baross & Hoffman, 1985). The distinct blue colour of t he ocean and the green colour of the terrestrial land is obvious on the Earth surface. Nevertheless, it is hardly to observe the entire view of the surface because of the scattering effect (Adams, 1934) and screening effect of the cohesive cloud in the atmosphere. Differences between the earth’s atmosphere and other planetary atmosphere including the presence of oxygen and relatively low carbon dioxide concentration.The atmosphere is extremely important to the biosphere. Without atmosphere, organisms nowadays would probably remain in the simple form or single celled. Furthermore, the ozone layer in the atmosphere absorbs and reflects part of the solar radiation incoming from the sun. This reduction of solar radiation lowers down the atmospheric temperature dramatically which allows organisms to survive. The Earth would not be so unique among the solar system when missing either one of the systems. The Gaia hypothesis links this concept and indicates the Earth is a giant self- regulating system.The interactions of the organisms with their abiotic environments modified the condition of the Earth such as oxygen content and atmospheric temperature, making the Earth more habitable terrestrial planet (Lovelock, 1973). Evolution of the Earth: Allegre and the research team (1995) suggested that the Earth was formed 4. 53 to about 4. 7 Ga. The age range of the earth was estimated by means of a series of isotope dating so the results are relatively valid. The Earth queues the third planet from the sun and its average radius is 6371 km (Lide, 2000).Because of specific distance from the sun and the size, the Earth prevents some of the very light elements, such as hydrogen, from escaping, by gravitational force (Adams, 1934). Moreover, the Earth has a gravitational force of 10 g (Yoder, 1995). Gravitational force is an inconspicuous pull generated from the Earth core. The Earth self-spins once it is formed. The rotation period of the earth is 23 hours and 56 minutes (Gold, 1967). This spinning effect creates centrifugal force which differentiate substances by mass. Heavy metal tends to migrate toward the Earth core and leaving the light materials outside.When time passes, the surface of the earth cools and the first land formed. Although land also appears in other planets such as Mars, the crust of the Earth is different. Interestingly, unlike Mars, the Earth surface is not covered by a concrete sphere but a few tectonic plates. Since the Mars is much smaller than the Earth so the cooling effect of Mars is much faster than the Earth. By now, the crust of the Mars has not been renewed for a certain long period. The plate tectonic moves with three strategies, convergency, divergency and transformation. The movement of the plates driven by the underneath semisolid magma (Courteny, 2008).Surface morphology is determined by the way which the tectonic plates move and density of the plates. Tectonic activities, earthquake, mountain-building, volcanic eruption and subduction zone, are restricted along plate boundaries (Courtery, 2008). Volcanic activities and oceanic subduction are extremely important processes to deliver materials from the inner core and renew surface materials respectively. These recycling processes keep providing accessible resources for the living organisms. Atmosphere and ocean formation was also suggested to be related to volcanic activities (Morbidelli, 2000).Aforementioned that self-spinning of the Earth differentiate substances on Earth. Iron, as a metal that can be magnetized, and with accordingly high atomic mass, moves inward and forms the core. After 60 million years after the late Heavy Bombardment, the magnetic field was established (Staff, 2010). Studies from Karato (1993) implies the magnetic field may relate to the magnetizing properties of iron. No matter how the Earth’s magnetic field was formed, it â€Å"prevents the atmosphere being stripped away by the solar wind† (Staff, 2010 ). Atmosphere: The atmosphere is the outermost, thin layer enclosing the Earth.The composition of the atmosphere for example, oxygen, is imperative to the evolution of the Earth. The atmosphere of the Earth is comparable to the nearby terrestrial planet such as Mars and Venus. Given that the average distance and the size of Venus from the sun is 3/4 and 4/5 of the Earth, Venus has an atmosphere (Adams, 1934). Spectroscopic studies indicate that the atmosphere of Venus does not show any markings representing the presence of oxygen and water vapour, even if these elements, once, had been appearing on Venus, they were consumed by the crust.Another result in the same spectroscopic concluded that the Venus atmosphere contains a high concentration of carbon dioxide, triggering a sever greenhouse effect (Adams, 1934). In addition to Venus, the Mars with only one tenth by the mass of the Earth also has an atmosphere. Spectrograms studies raised significant markings on ? 8300 and ? 8700 reco gnizes the appearance of water and carbon dioxide respectively on the Mars atmosphere(Kaplan et. al. , 1964). The presence of water on Mars is obvious with the ice cap present in the polar region of Mars (Adams, 1934).Not surprisingly, oxygen absents in Mars atmosphere and was proofed by the light frequency relative to carbon dioxide was not absorbed by the Mars atmosphere (Kaplan et. al.. 1964). From the example of Venus and Mars, it clearly shows that containing such a high concentration of oxygen, 21%, with extraordinary low carbon dioxide concentration, 0. 03%, as the Earth’s atmosphere is uncommon in the solar system. The composition of the Earth atmosphere provides with evidences that it has been modified by some other factors. This modification, as we know, was conducted by plants.Plants inhale carbon dioxide and exhale free oxygen as a by-product through the process of photosynthesis, inorganic substances were also converted into organic substances during the process (Berkner & Marshall, 1965). Free oxygen facilitates the evolution of organisms because high oxygen concentration triggers aerobic respiration, without oxygen, organisms nowadays would probably remain simple (Fenchel & Finlay, 1994). Differences between aerobic and anaerobic respiration not only limit on the requirement of oxygen, the oxidizing power and good electron accepting properties of oxygen boosts energy metabolism (Babcock, 1999).Babcock (1999) also stated that aerobic respiration releases much more ATPs than anaerobic respiration, ATP can be treated as the energy storage unit in organisms. In other words, organisms undergo aerobic respiration can perform more vigorous activities or prolong the duration of the activities. Furthermore, the ozone layer derived from the excess free oxygen incubated a habitable environment for living organisms. The ozone layer with related to energy budget and the effect on human was well examined in Norway (Adams, 1934; Henriksen, 1990) .The ozone layer prevents living organisms burnt to death by screening out part of the UV-radiation reaching to the Earth surface. Hydrosphere: By the time when Earth was just formed, water from asteroids,  proto-planets, and  comets was locked in the core. Volcanic extrusion and outgassing brings magma along with dissolved gas and water vapour to the surface respectively. Extruded gas and water vapour suspended in the atmosphere therefore atmospheric pressure continuously increases. Water condenses when the atmospheric vapour pressure is saturated.Water droplets fall onto the ground and ocean formed (Morbidelli, 2000). Liquid water is an advance heat reservior because of having an extremely high specific heat capacity, 4200J/kg/?. This significantly high specific heat capacity, in other words, a large sum of energy can only result in a small extent of changes in temperature of water. The high energy absorption ability combined with the ocean current makes the ocean a good vecto r for transporting absorbed solar energy and regulating global climate (Michon, 2006). Apart from an excellent thermal reservoir, liquid water is also a good solvent.Gases in the atmosphere and minerals from the hydorthermal vents can easily dissolve into the water. Dissolved gas and minerals has planted a seed to the extensive evolution of life throughout the geological time (Morris, 2007). Biosphere: As we discussed the geosphere, atmosphere and the hydrosphere above, these systems have one thing in common. All the systems are linked with the biosphere. Although other planets in the solar system exhibit either physical feature, mostly not more than two, with Earth. The true uniqueness of the Earth raised from the presents of life which cannot be found on other planets recently.The origin of life is still a hot arguing topic among groups of scientists. However, the hydothermal vent is the most commonly and recently acceptable concepts of the origin of life (Baross & Hoffman, 19 85). The origin of life via submarine hydrothermal vent hypothesis has not been disproved yet since it was published because there are no other environment on Earth can provide a thermo-stable habitat with abundant minerals supply, for example, nitrogen and sulphur, for life establishment (Baross & Hoffman, 1985). Photosynthesis is considered as a key issue of the origin of life (Hartman, 1996).Bacteria record found in western Australia, dated as 3. 5 billion years ago, stated that cyanobacteria may be the first autotrophic organism and responsible for the later atmospheric modification (Awranik, 1992). This key process opens the window of free oxygen, hence considerably boosted the evolution of organisms. The GAIA Hypothesis: Every system discussed above has its own features and contributions within the system boundaries. There is no doubt that every literatures when emphasizing the planet Earth, it can hardly find any paper just put the focus on a single system.The same situat ion can also be observed in this article. For example, in the discussion part of the origin and development of the atmosphere, the tectonic activities and outgassing processes were mentioned. Moreover, a similar case was obtained when investigating biosphere. Although the whole part is bias towards living organisms, the effect of atmosphere to the biosphere can hardly be eliminated. The above situation is not due to the habit of the authors or the regulations of the publishers but it is the real case of the Earth.All systems on the Earth, including geosphere, atmosphere, hydrosphere, biosphere or even self-defined systems, are interdependent. These systems interact with each other to create a more habitable planey. This complex interaction has long been observed by James Lovelock (1973) and explained in the GAIA Hypothesis. GAIA hypothesis suggested early life form achieve some sort of ability to control the global climate and the effect is still active. Lovelock (1972) stated that once the life exist on Earth, the physical environment and the chemical states had resulted a dramatic change.For example, the solar radiation level had increased dramatically since life exists. The Earth surface temperature, nevertheless, has only changed for a few degrees, throughout billion of years, compared to the current temperature. More interestingly, the rate and the extent of temperature change during the past billion years is so slow and mild respectively that the environment always permit the persistence of living organisms or provide long enough time for organisms to adapt. Without life, the atmosphere of the Earth will be similar to that of Mars and Venus.The above example, therefore, proved that the atmosphere we are now breathing is â€Å"biological contrivance† (Lovelock, 1972). The terms â€Å"Spaceship Earth† (Lovelock, 1972) was used to represent the planet where we are living. When astronauts were sent into the space, all the requirements for survi val can only obtain from the storage in the spaceship. If either system in the spaceship fails, astronauts will probably die. Conclusion: Doubtlessly, the Earth has many physical environments that absent in other planets. For example, liquid water and living organisms.However, what really makes the Earth rare is the interaction between different functional systems with unknown complexity. These interactions connected to the terminology of the â€Å"Spaceship Earth† meaning the Earth has the ability to self-regulate to adjust its own environmental condition that result in a harmonious giant system. Reference: Awramik, S. M. (1992). The oldest records of photosynthesis. PhotosynthesisResearch 33 (2): 75-89 Claude J. Allegre,  Gerard Manhes,  Christa Gopel, (1995). The age of the Earth. David R. Lide. (2000). 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