Global Warming: Causes and Effects - Article Example

GLOBAL WARMING: CAUSES AND EFFECTS 2006 INTRODUCTION The issue of global warming is not a new one: as early as a century ago, it was noticed that global surface temperatures began to rise after more than 9 centuries of gradual declining. In 1896, Svante Arrhenius, one of the first climatologists, published an article in the journal Philosophical Transactions. In that article the scientist forecasted that doubling of carbon dioxide concentration in the atmosphere would lead to increase of the global surface temperature by approximately 9ºF (Michaels, 2002). However, it was not until the past decade this phenomenon captured broad public attention. Starting from the early 1980s, a number of scientists from different countries across the globe have been reporting substantial increase in the atmosphere temperature. The most commonly cited reason for the rise is human activity, namely the Industrial Revolution which has led to exceedingly large emissions of carbon dioxide and several other gases being released into atmosphere. Pessimistic forecasts say that by the end of 21st century the overall increase in carbon dioxide concentration will cause the surface air temperature rise by 2°C to 5°C, while in the polar region the temperature may boost by 12°C (Jaworowski, 2004). Public and governmental concerns about the phenomenon of global warming peaked in 1997 when leaders of the industrially developed states gathered in Kyoto, Japan to sign a treaty limiting emissions of carbon dioxide. Despite seriously improved public awareness of the adversities allegedly caused by global warming, the issue still remains highly controversial both with public and scientific community. Unfortunately, global warming is a global phenomenon closely related to climate change. The time scale for such change is measured in centuries rather than in years, while the dynamics of the climate involves numbers of factors and variables and is still poorly understood. As a result, majority of Americans, though perceive the dangers of global warming, adopt laissez faire attitude: “until we are sure that global warming is really a problem, we should not take any steps that would have economic costs” (Sterman and Sweeney, 2001: 56). Such public indifference coupled with complexity of the climate change, long feedback time and non-linear nature of climatic processes, may be rather dangerous in the long-term perspective. CAUSES OF GLOBAL WARMING Although the final answer on the causes of global warming is still to be found, two major factors are normally referred to as the causes of global warming. These factors are excessive emissions of carbon dioxide and other ‘greenhouse’ gases and periodic fluctuations in temperature trends. While neither of these theories relies on decisive evidences, each of them has many advocates whom cite various scientific and non-scientific arguments in support of their viewpoint. During the last decades of the 20th century global warming was predominantly viewed as one of numerous side effects of human activity. 99.9% of the overall atmospheric volume belongs to only three gases: nitrogen (78.09%), oxygen (20.95%), and argon (0.93%). However, the climate depends on these three major gases much less than it depends upon the remaining groups of gases that constitute only 0.01% of the Earth’s atmosphere. These gases are carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), nitrogen oxides (NOx), chlorofluorocarbons (CFCs), and ozone (O3) and they are known as “…greenhouse gases or radiatively important trace species (RITS). They are radiatively important because they influence the radiation balance or net heat balance of the Earth” (Hardy, 2003: 3). For nearly three centuries the mankind has been raising the concentration of carbon dioxide and other ‘greenhouse’ gases in the atmosphere. Numerous factories, fossil fuel power plants and vehicles produce astonishing volumes of carbon dioxide; millions of tons of decomposing garbage coupled with highly increased population of methane-belching cattle result in release of excessive volumes of methane; nitrogen-containing fertilizers – the cornerstone of contemporary agriculture – raise concentration of nitrogen oxide. In figures, the rise seems rather impressive: while the preindustrial concentration of CO2 in the atmosphere did not exceed 280 ppm, these days the concentration of this gas is approximately 370 ppm which corresponds to more than 30 percent increase. The same tendency is observed in concentration of other greenhouse gases. Thus, concentration of methane and N2O has been raised by 151% and 17% respectively over the last 250 years. The Intergovernmental Panel on Climate Change (IPCC) reports these values to be the highest ever in the history of mankind: “The present CO2 concentration has not been exceeded in the last 420,000 years and likely not during the past 20 million years. The current rate of increase is unprecedented during at least the past 20,000 years” (IPCC 2001: 7). Highly increase concentrations of greenhouse gases cause serious imbalance in heat exchange taking place in the atmosphere: “Current greenhouse gas concentrations contribute about 2.4 watts per square meter of net radiative forcing, that is, incoming solar radiation exceeds outgoing radiation by 2.4 w/m2” (Sterman and Sweeney, 2002: 56 ). As a result, the average global surface temperature has risen by 0.6 ± 0.2 °C over the last century, which entailed retreat of glaciers, “…a decline in winter snow cover, a 40% decline in summer sea-ice thickness in the arctic, an increase in average precipitation and in extreme weather events, and a rise of 0.1 – 0.2 meters in sea level, among other effects (IPCC, 2001: 8). Although advocates of the greenhouse effect caused by human-induced increase in concentration of carbon dioxide and other greenhouse gases slightly differ in their approaches and explanations, they all agree that the consequences of it will be negative, especially in the long-term perspective. They claim that radical actions (particularly in terms of reducing greenhouse gases emissions) must be taken immediately by the international community to slow up the process of global warming and prevent or at least alleviate adverse climate changes. However, they also admit that considering the time scale for climate change processes, the results of such actions will hardly be observable in the nearest decades or even centuries. Despite seemingly convincing arguments in support of human-induced greenhouse effect, many scientists argue that human activities might exert practically no influence on the process of global warming. Proponents of this approach also provide various arguments to prove their point. Throughout traceable history of our planet, concentration of greenhouse gases the atmosphere changed many times. Each change was followed by certain changes in climate. Therefore, the climate developments we have been witnessing recently can hardly be considered unusual: they reflect natural planetary and solar trends. As Z. Jaworowski, the renown researcher of global warming notes “…from time immemorial, alternate warm and cold cycles have followed each other, with a periodicity ranging from tens of millions to several years…. the cycles were most probably dependent on the extraterrestrial changes occurring in the Sun and in the Sun’s neighborhood” (Jaworowski, 2004: 53). Historical analysis of known temperature variations that have occurred over the last several centuries demonstrates that since 1000 AD the range of temperature variations has been within approximately 1.5˚C. Apparently, those variations were not due to the greenhouse effect: the concentration of greenhouse gases in the atmosphere is considered to be constant until the Industrial revolution in the middle of 18th century. Surprisingly, temperature variations over the last 150 years were absolutely within this natural range: • 1860-1920 – Global temperature was about 0.3˚C cooler than the average. • 1920-1940 – Global temperature rose by about 0.35˚C to slightly above the average. • 1940-1975 – Global temperature shows a gradual cooling of perhaps 0.1˚C. • 1975-1990 – Global temperature rose above the average by about 0.3˚C (Houghton, 2001: 213). Failure of the forecast given by Arrhenius (a very similar prediction was also made by NASA scientist Hansen in the 1980’s) also provides some support to this point of view: although the concentration of greenhouse gases increased by nearly 50%, the temperature increase much less than it was predicted to (Michaels, 2002). Scientists sticking to this ‘natural variations’ point of view admit that certain terrestrial factors may have some influence on the short-term temperature changes. However, human-induced increase in concentration of greenhouse gases is not considered a highly important factor in this regard: volcanic explosions, variations in oceanic currents, thermal energy produced by natural radionuclides and some other natural phenomena contribute to the changes much less within this perspective on the global warming (Jaworowski, 2004). EFFECTS OF GLOBAL WARMING Potential effects of the global warming described in the literature vary greatly ranging from positive/neutral to negative/catastrophic. However, reliability of the predicted effects leaves much to be desired, especially when it comes to the long-term perspective. Researchers making the predictions do not have any empirical data to rely upon; instead they use computer climate modeling methods which are highly unreliable. As a result, some scientists consider that global warming will hardly have any major impact on the everyday climate conditions, while others argue that once the planet’s surface temperature reaches certain unknown threshold, “…the heat will trigger relatively drastic changes to the atmosphere and the oceans and transform the Earth’s weather patterns in a matter of years” (NASA, 2002: 3). Hurricanes and heavy storms are probably the most widely discussed and feared effects of the global warming these days. Theoretically, the influence of global warming on intensity of hurricanes and tropical cyclones is possible due to alterations of the surface energy flux and/or the upper-level cold exhaust (Henderson-Sellers et al., 1998). However, there is absolutely no reliable evidence that frequency of hurricanes and cyclones will increase due to global warming. Hundreds of studies dedicated to this subject provide highly controversial results which are “…too poor a foundation to base any projections about the future” (Pielke et al., 2005: 1573). Another debated result of the global warming is sea-level rise caused by melting of continental glaciers and the Greenland Ice Sheet. According the IPCC estimates, the level of sea will increase by 9 to 88cm by 2100 (IPCC, 2001). Apparently, even so slight rise of the sea level is likely to cause severe damage to highly populated coastal regions. On the other hand, the predicted rise is far from being catastrophic: the West Antarctic Ice Sheet that can potentially raise the sea-level by several meters is forecasted to remain for the nearest century at least (NASA, 2002). Biologically, global warming is predicted to alter natural habitats. Majority of these changes are considered to be negative, while some of them are believed to be positive. The negative changes comprise disappearance of certain animals, fish and plants, emergence of new deserts, while positive changes include intensive growth of forests and algae and improved life conditions for certain fish. REFERENCES Arrhenius, S., (1896) “On the influence of carbon acid in the air upon the temperature of the ground” Philosophical Transactions, 41: pp. 237–276. Hardy, John T. (2003) Climate Change: Causes, Effects, and Solutions. John Wiley & Sons, Ltd. Henderson-Sellers, A., and Coauthors (1998) “Tropical cyclones and global climate change: A post-IPCC assessment” Bulletin of American Meteorological Society, 79: pp. 9–38. Houghton, J. T. et al., Eds. (1991) Climate Change: The IPCC Scientific Assessment, Cambridge University Press, Cambridge, 1991. In addition to the IPCC, assessments have been published by the National Research Council. IPCC (2001) Climate Change 2001: The Scientific Basis. Summary for Policymakers: A Report of Working Group 1 of the Intergovernmental Panel on Climate Change. IPCC Third Assessment Report [available at www.ipcc.ch ] Jaworowski, Z. (2004), “The Ice Age Is Coming: Solar Cycles, Not CO2, Determine Climate”, 21st Century Science & Technology, Winter: pp.52-65 Michaels, Patrick J. (2002) “Global Warming and the Kyoto Protocol: Paper Tiger, Economic Dragon”, American Legislative Exchange Council (ALEC), Energy, Environment, Natural Resources, and Agriculture Task Force NASA (2002) “Global Warming”, The Earth Science Enterprise Series, NF-222 [available online at http://earth.nasa.gov ] Pielke, R. A.., C. Landsea, M. Mayfield, J. Laver, and R. Pasch (2005) “Hurricanes and Global Warming”, BAMS, 8(1): pp. 1571-1575 Sterman, John D. and Linda Booth Sweeney (2002) “Cloudy Skies: Assessing Public Understanding of Global Warming” System Dynamics Review, 18(2): pp.52-86 Read More