Global Warming Essay

Large tracts of forests worldwide are now being cleared. Some are already cleared for industrial or agricultural purposes. The remaining trees may not be enough to absorb the carbon dioxide in the atmosphere. The carbon dioxide is used by plants to manufacture food. It is also called a greenhouse gas. This kind of gas retains heat longer compared to other gases. Surface temperature rises as more trees and plants are cut or destroyed. The resulting high surface temperature due to the accumulation of the carbon dioxide is referred to as the greenhouse effect. Carbon dioxide in the atmosphere acts like the glass in a greenhouse. It traps heat from the environment. It causes air temperature to rise. The glass of the greenhouse prevents warm air from escaping (Williams 63-66). The air temperature inside the greenhouse rises as a result. This would lead to global warming. Moreover, global warming pertains to an increase of the temperature of the Earth’s atmosphere and oceans in these present days. During the 20th century, the atmospheric temperature of the earth increased 0. 6  ± 0. 2  °Celsius. The upsurge amounts of carbon dioxide and other greenhouse gases are the major causes of the component of warming. They are produced through the burning of agriculture, fossil fuels and land clearing and may precede to an upsurge in the greenhouse effect. There is an initial assumption that a greenhouse effect possibly takes place because of the Swedish chemist Svante Arrhenius during 1897(Jenner et. al 258). In addition, climate sensitivity denotes to the equilibrium response to upsurge greenhouse gases and different anthropogenic and â€Å"natural climate forcing† (Davidson 325). This will be revealed through observational and model researches. The said sensitivity is generally showed through the temperature response that is anticipated â€Å"from a doubling of CO2 in the atmosphere† (Davidson 325). There is a report in 2001 from the Intergovernmental Panel on Climate Change (IPCC) that evaluates the climate sensitivity between the scales of 1. 5–4. 5  °C. The intents of this paper are to: (1) understand what global warming really is; (2) know about the historical warming of the earth; (3) figure out the causes of the global warming and; (4) find out the expected effects of global warming. II. Background A. What is global warming? Global warming is defined as â€Å"the increase of average world temperatures as a result of what is known as the greenhouse effect† (Bellamy et. al 145). This would mean that it is an intense upsurge of world temperature which is the outcome of so- called greenhouse effect. There are many factors why the world is experiencing global warming. And one of these factors is the human activities like cutting down of trees that are supposedly be the one absorbing the carbon dioxide in the atmosphere. There are gases in the atmosphere that portray as glass in the greenhouse which permits sunlight to warm the surface of the earth but trap the heat when it â€Å"radiates back into space†( Bellamy et. al 157). When the greenhouse gases formed in the atmosphere, the earth starts to get warmth. Nowadays, most countries experienced global warming. It is one the outcomes of people’s irresponsibility because humankind tends to destroy the forest by cutting the old trees and never replaces them. The graph below shows the global temperatures from 1860 to 2000. Moreover, the earth’s surface is warmed by the Sun and radiates heat back into space. Gases such as carbon dioxide, nitrogen oxides, methane and CFCs in the atmosphere trap some of this heat, and warm the lower atmosphere. The atmosphere radiates heat back to Earth. This is called the â€Å"greenhouse effect†, and without it the Earth would be so cold that life could not exist. But many scientist fear that the huge amounts of these â€Å"greenhouse gases† released into the atmosphere by industrial processes and burning fossil fuels are warming the earth so much that they will eventually upset the world’s climate, and cause sea levels to rise. In addition, some scientists predict that the earth’s temperature could rise 3  °C by 2070. After this, the rise will level off and the temperature will stabilize (Bellamy et. al 163). If the Antarctic ice sheet melted, sea levels could rise; threatening low-lying areas such as the US coast. B. The earth’s energy balance. But for the greenhouse effect, life on Earth would not exist. The Sun emits radiation to the Earth. If we could imagine a flat surface at the top of the atmosphere, that radiation is about 340 watts per square meter (340 W/m-2). Just over 100 W/m-2 is reflected out again by atmospheric aerosols and clouds, and the Earth’s surface, leaving some 240 W/m-2 that heat up the surface of the Earth (Carwardine 76-77) . The system must be in balance—energy â€Å"in† must equal energy â€Å"out†Ã¢â‚¬â€so the Earth needs to re-radiate this amount back into the atmosphere. But the amount actually re-radiated depends on the Earth’s surface temperature: the hotter the surface is the more it will emit radiation. The outgoing radiation takes the form of â€Å"long wave† infrared thermal radiation. If the system balanced â€Å"naturally†, then the Earth’s surface would have a temperature of about –19 ° C (-66 ° F) since at this temperature 240 W/m-2 would be emitted (Carwardine 98). Obviously, something else must be happening because at such low average temperatures life would not exist. The Earth’s surface is very much warmer than this â€Å"natural† level (around 15 ° C/59 ° F) and hence far more radiation is emitted than the 240 W/m-2. What happens is that a lot of the Earth’s re-radiation bounces back to the Earth’s surface because it gets absorbed mainly by water vapor and carbon dioxide (CO2) in the atmosphere. Water vapor, CO2, and a few other minor gases act like a â€Å"blanket†. The balance is secured as follows: Incoming solar radiation: + 340 W m-2 Reflected from clouds, the Earth’s surface, etc. : – 100 W m-2 Net incoming radiation absorbed by the Earth = + 240 W m-2 Outgoing radiation: – 420 W m-2 Greenhouse effect: + 180 W m-2 Net outgoing (thermal) radiation = – 240 W m-2 The way the system balances, then, is that the Earth’s surface warms up compared to what would happen if the Earth was not surrounded by a blanket of greenhouse gases. C. The anthropogenic greenhouse effects. The greenhouse effect refers to the way in which gases in the Earth’s atmosphere warm the Earth like the glass roof of a greenhouse—by letting sunlight in but keeping the reflected heat energy trapped inside (Johnston 550). These naturally occurring gases, notably carbon dioxide and water vapor, are called greenhouse gases. III. Discussion A. Historical warming of the earth During 1860-1900, global temperatures on seas and on lands had experienced great upsurge of temperature by 0. 75  °C as recorded in the instrument temperature record. Beginning in 1979, the land temperatures had doubled which was the same as the ocean temperatures. And in that year, the temperatures below the troposphere had upsurge between 0. 12 and 0. 22  °C every 10 years as recoded in the satellite temperature measurements. It was believed before that world temperature was stable two thousand years in the past 1850 with the assumption that temperature was stable maybe because of the regional wavering like the Little Ice Age or Medieval Warm Period (â€Å"Temperature record of the past 1000 years†. Wikipedia, the free encyclopedia). The graph below illustrates the reconstructions of Northern Hemisphere temperatures for the last 1000 years as stated to several older articles. B. Causes of the global warming There many causes why global warming is happening at present. These causes are generally or mostly based on man’s conduct. The causes why there is global warming because of the release of carbon dioxide from power plants, emitted cars, trucks, airplanes, buildings, methane, nitrous oxide, deforestation, city gridlock and carbon in atmosphere and ocean . C. Effects of global warming The great effects of global warming to our environment and for humankind are plentiful and wide-ranging. The major effect of global warming is the upsurge global average temperature. It also leads to â€Å"rising sea levels, altered patterns of agriculture, increased extreme weather events, and the expansion of the range of tropical diseases† (Johnston 554). The anticipated climate changes are also one of the effects of global warming. Not only that, it also affects the weather condition. IV. Conclusion Global warming has great effects to our environment especially to humankind. Global warming has many factors why it is occurring. One of these reasons is deforestation. Deforestation makes our environment warmth because of the remaining small amount of trees that are unable to absorb the large amount of carbon dioxide in the atmosphere and because of this; carbon dioxide traps the heat in the environment that causes the temperature to rise because it stops warm air to escape. References: 1. Bellamy, D. and Gifford, J. 1999. Wilderness Britain? a Greenprint for the Future. Sparkford: Oxford Illustrated. Popular work by leading biologist and environmental campaigner. 2. Carwardine, M. 2002. The WWF Environment Handbook. London: Macdonald Optima. Attractively illustrated handbook for the general reader. 3. Davidson, J. 2000. How Green is your City? Pioneering Approaches to Environmental Action. London: Bedford Square Press. Guide to community action for urban renewal.