Global Warming: Debate Continues on Actual Causes and Possible Effects - Term Paper Example

Global Warming: Debate Continues on Actual Causes and Possible Effects Introduction The dominant scientific opinion is that the earth's average near-surface temperature has risen by 0.6 degrees Celsius in the 20th century, but disagreements persist on what precisely causes global warming and whether its effects represent a real threat to life on earth. Generally, greenhouse gases that collect in the atmosphere get the blame for global warming, since this supposedly triggers climate change that in turn leads to such ecological aberrations as ozone layer depletion, rising sea levels and changes in the pattern and amount of precipitation. Such changes in precipitation then serve to increase the frequency and intensity of extreme weather events like floods, droughts, heat waves, hurricanes and tornados. However, other scientists maintain that man and his carbon dioxide emissions are not solely to blame for the temperature changes, that prediction of these changes is has yet to become 100 percent accurate, and that the perceived temperature rise can never annihilate life on earth. This paper examines the clashing scientific opinions less for the purpose of determining which side presents the stronger arguments but more for drawing the information on the causes and effects of global warming. Causes The greenhouse effect theory postulates that the gases and carbon dioxide expelled by people through the burning of fossil fuels, land clearing and agriculture collect in the atmosphere and cause the earth's average temperature to rise (Whipple 12). According to this theory, the anthropogenic or manmade carbon dioxide released into the atmosphere in the past 400,000 years doubled since the Industrial Revolution, which was then helped along by the natural changes in the Earth's orbit around the sun to cause global warming (Taylor 8). Increase of such carbon dioxide in the atmosphere warms the Earth's surface and leads to the melting of polar ice caps. As the ice melts, land or open water appears in its place, neither of which is as reflective as ice and thus absorbs more solar radiation (Murray 6). This causes more warming and more melting. Thus, most scientists believe greenhouse gases are the primary cause of global warming such that human activity is entirely to blame for this phenomenon. Indeed man is responsible for at least some of the greenhouse gases and carbon dioxide emissions, but many climate experts dispute the view that ascribes temperature changes to rising carbon dioxide levels. The US National Academy of Sciences took the same position when it declared in 2001 that the link between greenhouse emission and climate change cannot be established equivocally because of the "large and still uncertain level of natural variability" in the climate. If at all, only three-quarters of manmade emissions of CO2 during the past 20 years is due to fossil fuel burning, since the rest is due to atmospheric soot, land use changes, land clearing and agricultural activities, especially deforestation (Castles 5). Methane, a byproduct of natural gas, also enters the atmosphere from biological production and leaks from natural gas pipelines and similar structures (Castles & Henderson 9). Other biological sources of methane are not anthropogenic such as termites, and non-human causes include volcanic emissions and solar variations (Lee 43). In this view, the role of greenhouse gases in global warming has been overblown (Zwally 7). The relationship between global warming and hurricanes is another subject that is hotly debated. If the world's climatic scientists agree on one thing, it is on the increasing force of recent hurricanes such as Hurricane Katrina, which swept the Americas and Europe in 2004. The consensus is that no natural calamity in memory matched the scope and magnitude of the damage Katrina wrought on lives, property and the economy. However, research by a group of German scientists argues that the devastating floods in central Europe in 2002, for example, were perfectly normal events based on historical record. Other hurricane scientists agree that it is inaccurate to blame global warming for Hurricane Katrina. Allegations that extreme weather events had become more damaging lately do not take into account the fact that human beings now live and invest resources in more dangerous areas, such as mountainside and seacoasts, which are more susceptible calamities. To some scientists, the increase in the recorded number and force of these weather disturbances may be actually due to better observation and reporting methods. Thus, when the Inter-government Panel on Climate Change (IPCC) claimed that global warming exacerbated the 2004 hurricane season that produced Katrina, a top IPCC expert resigned in January 2005 in complete disagreement. Philip Klotzbach of the Colorado State University said that based on his own studies, most increases in Category 4-5 hurricanes between the period 1986-95 and 1996-2005 are due to improved observation and measurement technology. This indicates that other factors dictate the intensity and frequency of tropical cyclones. Effects The oft-cited effects of global warming in general terms are more precipitations, glacial movements, sea level increases and extreme weather variability. Partly responsible for these events is the depletion of the ozone layer, which serves as screen to protect the earth from the harmful effects of the sun (Lee 23). Scientists believe the unabated fossil fuel emission has punctured the ozone layer to deprive the planet of sufficient protection against the warming effects of the sun (Whipple 11). The result is climate change characterized by more frequent and devastating weather occurrences like floods, droughts, heat waves, hurricanes and tornados. In the polar region, glaciers will retreat or disappear altogether to trigger flash floods, landslides, glacial lake overflows and a yearly variation in water flows of rivers. Already, the total surface area of glaciers worldwide has decreased by 50 percent since the end of the 19th century (Whipple 13). The melting of glaciers and ice sheets is also believed to be a direct result of the increasing levels of carbon dioxide in the atmosphere. This causes thermal expansion and ocean acidification, which contribute to warming of ocean surfaces that then lead to the rise in sea levels and inundation of low-lying areas (Emanuel, et al. 19). The reason is that as the temperature of oceans climbs, their capacity to absorb excess CO2 is diminished. Meanwhile, the increase in sea levels will also intensify saltwater intrusion into groundwater reserves in some regions to deplete water supply for drinking and agriculture starting in coastal zones (Murray 13). Climate change brought on by global warming also means decreased rainfall and an increased risk of drought, which condition becomes susceptible to forest fires and crippling to rain-fed agriculture in many areas (Running 5). In other words, rising atmospheric temperatures mean prolonged droughts and reduced crop yields. All these suggest a change in the ecosystem, which means mass extinction for some species of animals and birds that will be forced out of their habitats or could not adapt to the new conditions. The increased temperature in the global surface itself will induce the outbreak of cardiovascular and respiratory diseases as well as insect-borne diseases like dengue fever and malaria, which will happen because warmer climate promotes the breeding of disease vectors (Emanuel, et al. 13). Conclusion Carbon dioxide emission persistently emerges in climate change discussions as the primary cause of global warming, although scientists could not agree on the extent of man's responsibility in it. These greenhouse gases come not only from factories and motor vehicles but also from other manmade activities such as land-use conversion, land clearing and deforestation. However, man is only party to blame because nature also does its share. For example, scientists consider volcanic emissions, atmospheric soot and methane naturally exuded by forests as contributors to global warming. So is solar variations, or the cyclical changes in the position and heat of the sun. These are the supposed causes of global warming, which all combine to effect changes in the earth's average near-surface atmosphere such that when it climbs by several degrees Celsius, it induces extreme weather events noted for their greater frequency and intensity. These weather events include damaging floods and drought, extinction of animal and bird species and increase of insect-borne diseases. Extreme weather events have indeed become more vicious and frequent in recent times but there had been natural calamities in the past as devastating as, say, Hurricane Katrina. So the scientific community needs to resolve once and for all whether these are a naturally occurring phenomenon, or induced by global warming that was in turn brought about by fuel emissions from industries. The problem is that, based on a scan of the materials written on the subject, the doomsday predictions of global warming catastrophe have relied heavily on economic factors and less on science. Some sectors of the scientific community refuse to accept these doomsday scenarios. True, global warming is happening and that man is partly responsible for its occurrence but it does not mean that it will cause enough damage to earth and humanity as to require drastic cuts in energy use, which would have unimaginable consequences of its own7. Predictions of a 6 degrees Celsius rise in temperature over the next 100 years are said to be the results of faulty economic modeling, not science. Theories that blame greenhouse gases for global warming are also believed to be erroneous, since significant contribution has also been made by atmospheric soot, land use change and solar variation. The US National Academy of Sciences itself casts doubt on the dire predictions of the doomsayers, saying that the 20 years' worth of knowledge and data on this discipline is not long and sufficient enough to estimate long-term trends with accuracy and certainty. This position seems to have been validated by the so-called Heidelberg Appeal, which was recently signed by 4,000 scientists from around the world, including 70 Nobel Prize winners. The appeal exhorts the industrialized world to go easy on fossil fuel regulation, saying that no compelling evidence as yet exists to justify radical controls of anthropogenic greenhouse emissions. References 1. Castles, I. & Henderson, D., 2003, The IPCC Emission Scenarios: An Economic- Statistical Critique, Energy and Environment, Nos. 2 & 3. 2. Castles, I., 2002, Greenhouse Emission Calculations Quite Wrong, Canberra Times, 29 August 2002. 3. Emanuel, K., Sundararajan, R. & Williams, J., 2008, Hurricanes and Global Warming, American Meteorological Society, March 2008. 4. Jorgensen, D., 2004, US Market Consequences of Global Climate Change, Pew Center of Global Climate Change, Harvard University. 5. Lee, R.D., 1992, Trashing the Planet, Regnery Gateway, Washington DC. 6. Lynch, D., 2005, Corporate America Warms to Fight against Global Warming, USA Today. 7. Murray, I., 2006, Global Warming FAQ: What every Citizen Needs to Know about Global Warming, Competitive Enterprise Institute, No. 106; Washington DC. 8. Running, S.W., 2006, Is Global Warming Causing more, Larger Wild Fires" Science Express, Vol. 313, No. 5789. 9. Taylor, J., 1998, Global Warming: Anatomy of a Debate." John Hopkins University Applied Physics Laboratory. 10. Whipple, D., 2004, Dollar Effects of Global Warming, United Press International, Boulder, 4 May 2004. 11. Zwally, H.J., 2002, Mass Changes of the Greenland and Antarctic Ice Sheets and Contributions to Sea-Level Rise," Journal of Glaciology, Vol. 51, No. 175. Read More