Earth Energy Balance Issues - Term Paper Example

Earth Energy Balance Introduction: Sun is an essential source of energy for all the organisms on this planet and they benefit from it either directly or indirectly. There is little doubt that sun generate enormous amount of heat and radiation that travels a long distance to reach the earth. This energy then warms the earth and substantially influences the atmosphere around it. In a closed system, progressively everyday this heat energy would have accumulated and burned our planet like a giant microwave oven. But, this is certainly not the case because earth’s climate system is constantly returning most of the radiations that are projected on earth back into the space. This phenomenon is known as earth energy budget or earth energy balance. There are many factors that can deteriorate this balance and can contribute to significant changes in the climate of the earth. Earth Atmosphere: To understand how energy is received and returned to maintain energy balance it is important to understand what constitutes the atmosphere. There are five layers that surrounds the earth; exosphere, thermosphere, mesosphere, stratosphere and troposphere. Exosphere is the most outer space with particles so far apart that they do not affect the pathway of radiations from sun. Troposphere is the innermost layer that span from the earth surface to about 10 kilometers above. This layer is important as it provides the maximum reflection of radiation as discussed below. The following diagram (fig 1) demonstrates the inner three layers of earth atmosphere. Fig 1. Inner three layers of earth’s atmosphere Incoming radiation: Radiations from sun experience no interference as they travel undisturbed in space to reach the earth’s atmosphere. In the atmosphere, there are different layers with variable densities of gases and other molecules. When these radiations collide with these molecules they are deflected in many directions, a phenomenon known as scattering. An important concept to remember here is that these radiations that reach the earth have very small wavelength and not all but a small selective proportion of electromagnetic radiations can be scattered by molecular collision. (Ahrens, 2012). The rest of energy is absorbed by the earth system in various forms. Most of the energy is absorbed by the solid earth that increases the core and surface temperature. Part of the energy is absorbed by clouds, water vapors and other molecules present in the earth atmosphere. The following diagram (fig 2) represents the overall exchange budget of earth’s energy. Figure 2. Earth’s energy balance It is evident from the diagram that the total incoming energy absorbed by the earth system almost equals to the energy returned back to space thus maintaining energy balance. Outgoing radiations: The radiations received from sun can be returned back to space by two basic mechanisms as explained below. Reflection: Some of the energy that enters the atmosphere is reflected back as same short wavelength radiations identical to what was received from sun. Different component of earth’s atmosphere have variable ability to reflect these radiations and this property is known as ‘albedo’. Therefore, various surfaces have variable albedo. For example, deserts have high albedo because they are able to reflect about 40% of the radiations that reach them back into the space. On the other hand, ocean surfaces and rainforests have low albedo as they are able to reflect only a small proportion of radiations. (Ahrens, 2012). It is important to understand that those surfaces that have lower albedo tend to retain heat more than those with higher reflection abilities. By looking at fig 2, it can be observed that only a part of the radiations, about 30%, are reflected back into the space by earth surface, clouds and scattering process. There should be another way of returning the remaining 70% of the radiations which were absorbed by the atmosphere and the earth. Emission: Thermic emission is the most important process by which most of the earth and atmospheric temperature is maintained. Sun radiations absorbed by different earth and atmospheric surfaces is returned back as thermal emissions. Unlike reflected radiations, most of this energy is in the form of long wave radiations. (Ahrens, 2012). These radiations can either directly reach space or warm the atmospheric layers above that indirectly transfer this energy. All this process is summarized in the fig 2. Deteriorating the Balance: The energy balance of the earth is of great importance because any disruption in the normal system can affect the micro and macro environment of earth and surrounding atmosphere. There are various factors that have contributed in deteriorating the energy balance. Unfortunately, humans are responsible for most of these factors such as burning of fossil fuels and increasing the atmospheric pollution. Important question to ask here is what can theoretically cause disequilibrium so that the source of that factor can be traced. There is a greater possibility that the balance is deteriorated by retaining the energy rather than losing it. This simple means that not all the energy is sent back to space and some of it is retained. The possible mechanism is by hindering the pathways that return energy back to space as discussed earlier. For example, if reflected radiations are not allowed to escape into the space and they reflect back to earth. Another possibility is to alter the atmosphere around earth that hinders in the normal passage of surface energy into space in the form of emissions. All these mechanisms will increase the surface and atmospheric temperatures. Greenhouse effect: There are certain gases in the atmosphere that interferes with the normal return of reflected radiations into space and may scatter them in our environment increasing the atmospheric temperature. This phenomenon is called the greenhouse effect. There are certain gases naturally present in earth’s atmosphere that contributes in this effect and are called greenhouse gases. These gases include water vapors and carbon dioxide. Greenhouse effect is always considered as a negative entity which is a big misconception. The natural greenhouse effect is very important phenomenon that maintains the steady favorable temperature of our environment. Moon has no atmosphere, therefore, no greenhouse effect and its surface temperature is -18o C. On the other hand, earth has a surface temperature of about 15o C mainly because of this natural greenhouse effect. But the problems arise when excess of these greenhouse gases accumulates in the atmosphere and amplifies greenhouse effect. Most of these gases are released into the atmosphere by human activities. These gases include carbon dioxide, nitrous oxide, methane, perfluorocarbons, hydrofluorocarbons, sulfur hexafluoride etc. (Ramseur et al. 2008) Fossil Fuels: Most of the today’s world economy runs on fossil fuels. The combustion of these natural resources can largely contribute to the production of gases that can deteriorate the energy balance by mechanisms discussed above. The main greenhouse gas produced during fossil fuel combustion is carbon dioxide. Most common source is combustion smoke from traffic vehicles that also contributes to air pollution. Factories: Most of the factories require use of certain chemicals that are disposed off in the environment adding to greenhouse gases such as sulfur hexafluoride. Cutting trees: Human activities not only produce greenhouse gases it also decrease their natural removal from the environment. Trees and natural vegetations use carbon dioxide and light energy to produce food for survival of all species on earth. They are the primary producers and contribute enormously by keeping atmospheric carbon dioxide under normal concentration. But unfortunately humans are cutting them down to clear space and use them as a source of fuel or for other purposes. This removal of vegetations is in progress at an alarming pace which is far more than at which nature can replace them. Chlorofluorocarbons: This group of gases is most frequently used in aerosol sprays and in the production certain other materials. They have dual effect on the environment. These gases not only enhance natural greenhouse effect but also deplete ozone layer in the atmosphere (fig 1). Ozone is a protective layer that does not allow harmful ultraviolet radiations to pass through it. Thereby, preventing them to reach the earth surface, protecting humans from developing life threatening skin cancers and other abnormalities. (Peterson et al. 2012) Effect of Earth Energy Disequilibrium: Any disruption in the energy balance of earth can have long lasting and catastrophic effects. Major problem with heat retention is that it increases the surface temperature more than what is naturally or optimally required. This can lead to swirl in the natural cycle, mostly resulting in extreme variations in the weather. A very important impact of global warming is the melting of ice caps at the poles. This has led to rise in the sea levels that threaten more land to go under water. Moreover, this disruption has raised the risks for floods, droughts, hurricanes and other natural disasters that are weather dependant. (Ramseur et al. 2008). In a philosophical nutshell, nature takes its course to ensure that equilibrium is maintained which sometimes can be catastrophic for living beings. Unfortunately, humans are the main culprit in shifting this natural balance. Humans the only culprit? This is a very important question. There is no doubt that human activities as mentioned above contribute significantly in causing a disruption in earth energy balance. But are they the only culprit or there are other major factors that can play part in this environmental threat? An important natural greenhouse gas discussed before is water vapors. Recent research has shown that water vapors contribute more in global warming than what they have been credited before. The research report by Solomon et al published in 2010, highlighted that water vapor content of the stratosphere decreased after 2000, thereby, slowing the increase of earth surface temperature. The report continues to state that there is a limited data that suggest that water vapor content of stratosphere increased during 1980 to 2000, mainly contributing to the greenhouse effect that resulted in dramatic increase of earth surface temperature. This research study indicates that there are other factors apart from well known carbon dioxide that can significantly alter the earth energy equilibrium. Volcanic eruptions, a completely natural phenomenon, are common source of incorporating water vapors into the atmosphere. Therefore, it can be said that nature itself is partially disrupting the natural balance of this earth. Possible Solutions: By looking at the causative factors it is easy to formulate certain possible solutions to the problem. The most important factor is the combustion of fossil fuels that generates a lot of carbon dioxide. Finding an alternate energy source that can replace fossil fuels can help a great deal in solving this crisis. But this energy source should also be pollution free and must have clean air benefits. One possible solution is the use of solar energy to produce electricity. Moreover, vehicles that can make use of inbuilt solar panels are also under experimentation but a significant development is required before this technology can be introduced on large scale to replace fossil fuels. Other possible solutions include use of wind energy to generate electricity. Another source of energy that is used by few developed countries includes nuclear power plants that can fulfill significant energy needs. But these giant structures require proper management and prone to possible radioactive hazards that can have catastrophic outcomes. Conclusion: Energy coming to earth is returned back to space to maintain energy equilibrium. Earth energy balance is very important as any disruption can have significant consequences. Greenhouse effect is an important phenomenon that provides optimum surface temperature. But any excess effect can cause further abnormal increase in this temperature leading to melting of ice caps, increase in the sea level and other natural catastrophes. Both human and natural factors contribute to amplification of greenhouse effect. There are certain possible solutions to this problem but a coordinated global partnership is required to implement those solutions. Reference Ahrens, C D. Essentials of Meteorology: An Invitation to the Atmosphere. Belmont, CA: Brooks/Cole, 2012. Print. Petersen, James F, Dorothy I. Sack, and Robert E. Gabler. Physical Geography. Belmont, CA: Brooks/Cole Cengage Learning, 2012. Print. Ramseur, Jonathan L, Larry Parker, and Brent D. Yacobucci. Greenhouse Gases: Management, Reduction, and Impact. New York: Novinka Books, 2008. Print. Solomon, S, K.H Rosenlof, R.W Portmann, J.S Daniel, S.M Davis, T.J Sanford, and G.-K Plattner. "Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming." Science. 327.5970 (2010): 1219-1223. Print. Read More