I. Introduction This paper will argue that global warming has indeed affected the climate and has caused climate changes to occur on Earth. In particular, this essay will focus on three main effects caused by global warming: 1) the increase of average temperature; 2) changes in rainfall precipitation; and 3) increase of turbulent storms. For example, one of the major consequences of rising temperatures has been the melting of permafrost in Alaska, which is one of the hardest hit by global warming. Moreover, global warming has also affect the rainfall distribution; consequently, in some places there are increased droughts whereas others there are increased droughts. As well, the increase of turbulent storms have also been linked to global warming. Thus, recent storms such as El Nino have brought havoc to places such as the coast of Peru. Accordingly, global warming has certainly made some impact on human lives, be it large or small.
First and foremost, the science of global warming refers to an expected rise in global average temperature due to the continued emission of greenhouse gases produced by industry and agriculture which trap heat in the atmosphere. The phrase "global warming" or ""greenhouse warming" refers to the fact that as more carbon dioxide or other greenhouse gases are added to the atmosphere, the temperature of the earth will rise, assuming nothing else changes. Thus, global warming is caused by an enhanced greenhouse effect which means a new higher equilibrium temperature is reached (MacKay 2000). The reason is that for the past few hundred years, people have been burning fossil fuels such as coal and oil in ever increasing quantities. While some of the carbon dioxide released is absorbed into the ocean or taken up by plant life, in the short-term about half of it remains in the atmosphere (website 1).
However, more significantly, this essay will give the positive and negative perspectives on the effects of global warming. Moreover, although there is a strong consensus among the scientific community that global warming has indeed altered our climate, there is also a strong argument that global warming's effects are minimal, if it exists at all. This essay will try to analyze both arguments. In this essay, it should be noted, I will often use Fahrenheit and Degrees Celsius interchangeably for the purpose of not straying away from the originality of the source from which I have quoted them from, not for the purpose of confusing the reader.
II. Rising Average temperatures
There is a strong consensus in the scientific community that recent climate changes, most notably -rising temperatures-- is the result of global warming.. Average global surface temperatures have increased 0.6 to 1.2 degrees fahrenheits since the late nineteenth century. But more strikingly, the twentieth century's ten warmest years have all occurred within the last 15 years. Of these, 1998 was the warmest year on record (website 9) [refer to graph 2]. Hence, the 1990s were the warmest decade since measurements were first recorded in the 1800s. At the close of 1999, the World Meteorological Organization in Geneva Switzerland, it was reported that an increase in global mean annual temperatures of nearly 0.7ºC (1.3ºF) had occurred over 100 years. Other calculations put 20th century warming in the range of 0.4-0.8ºC(0.7-1.4ºF) (website 9).
Recent scientific research on the effects of global warming on rising temperatures have revealed that there is indeed a relationship between the two. Thus, there has been three separate but largely comparable and overlapping records of global surface temperature made by the University of East Anglia (Norwich, UK), the National Aeronautics and Space Administration's Goddard Institute for Space Studies (New York) and also the US National Oceanic and Atmospheric Administration (NOAA) covering the effects of rising temperatures in the twentieth century. Compellingly, all three compilations agree that 1998 was indeed the warmest year on record, the six hottest years were in the 1990s, and the ten hottest years on record all occurred since 1980. While 1999 was slightly cooler than 1998, it still ranks as fifth or sixth warmest on record, despite the cooling influence of the 1999 tropical Pacific La Nina (website 9). [see graph 1].
However, there are many skeptics of global warming. Despite dramatic surface warming observed over the past two decades, many skeptics argue that satellite temperature records, which measure the lower layer of the atmosphere from the surface to about five miles up, give a murky and inconsistent record. As a result, these measurements -covering 1979 to the present- show a relatively insignificant warming trend of 0.05ºC (0.09ºF) per decade. The difference between the obvious surface warming and the lack of a clear upward trend in the satellite data has generated controversy in the scientific community for the past decade with researchers on both sides pointing out problems with the other side's data (website 9).
Although global average temperature has changed by less than one degree Celsius (up or down) for ten thousand years and might appear small, the consequences are indeed the opposite. So the projected warming is expected to exceed any climate change which has occurred during the existence of human civilization (website 2). More significantly, even "apparently" small global average temperature changes can be accompanied by much larger regional climate shifts. In the past records Earth's global climate, apparently small global temperature average changes also led to large climate shifts. For example, Earth's average temperature increased by only about 9 degrees Fahrenheit between the end of the last ice age and today, but much of the Northern Hemisphere went from being buried under thousands of feet of ice to being ice-free (website 2). Thus, small temperature changes do make a tremendous difference. Disastrously, some scientists have predicted that a warming which is twice as large as the global average is projected to occur at high northern latitudes (website 2).
Nonetheless, even though warming of a 1°F over the past century and a further 2 to 6 degrees Fahrenheit over the twenty-first century, as projected by the Intergovernmental Panel on Climate Change (IPCC) , may appear minor compared to short-term weather changes from night to day and winter to summer, in global climate terms, a warming at this rate would be much larger and faster than any of the climatic changes over the past 10,000 years. Evidently, global temperatures during the last ice age (about 20,000 years ago) were "only" 9°F cooler than today, but that was enough to allow massive ice sheets to reach as far south as the Great Lakes and New York City (website 7).
One astonishing recent phenomenon of global warming's higher equilibrium temperature is the Alaskan example. Recent studies have shown that global warming appears to be hitting hardest in Alaska, where the permafrost is thawing (website 8). Consequently, global warming has caused average temperatures in Alaska to have risen one degree per decade over the past thirty years. More remarkably, just as some climate computer models had predicted, the strongest warming has occurred in winter (website 8). Similarly, since 1960, average annual temperatures not just in Alaska, but also the Arctic lands have risen by one degree. However, the most climatologists' attention points to Alaska and neighbouring northwestern Canada as the warming hot spot-with temperatures rising three times faster than across the Arctic as a whole (website 8). The ultimate consequence of this recent phenomenon is that a shift in atmospheric circulation in the mid-1970s, which brought more warm air to Alaska, enhanced the greenhouse effect (website 8). The warming is taking its toll on the patchy permafrost found across much of the state, south of the Brooks Range of mountains. Mean annual temperatures a metre below the surface have risen by more than 1 degrees Celsius in the past decade. This is melting parts of the relatively warm permafrost of interior Alaska, which was never more than a few degrees below freezing (website 8).
Nevertheless, global warming actually has both a positive and negative effect. Some areas would actually benefit from global warming even as other areas were harmed. For instance, certain farming areas have enjoyed a longer growing season, even though other areas have suffered from more frequent droughts. In fact, shortage of water have already been a tremendous problem in California, where 75% of its annual precipitation falls as snow in the Sierra Mountains to the north, while 80% of the state's total supply is consumed in the spring and summer in its central valley and southern countries (Bernarde, 1992). The ultimate consequence is that, coupled with less precipitation and more evaporation (because of global warming), California's water resources are being stretched to its limits (Bernarde, 1992). More notably, California has recently faced its worst drought in forty years and its water source will be further stretched as 85% of its available water is used to irrigate crops. Not surprisingly, with global warming continuing at its present rate, California has been forced to set up water conservation and water "recycling" and reuse programs in order to stabilize its water supply shortfall (Bernarde, 1992)
However, many present-day skeptics of global warming support a controversial "heat island" theory which de-constructs the occurrence of rising global warming. It bases its argument on the fact that global warming readings and data are often skewed since most scientists record temperature changes from labs in urban areas. Thus, because urban areas have many buildings with vertical walls, these walls act like light traps or cavities and capture and store heat during the day and then re-emit it at night (website 6). Thus, cities and towns are nothing but enormous collections of "Trombe" walls. Not surprisingly, these areas are warmer than the surrounding country and, in particular, are warmer at night. In fact, this has been a known fact since at least 1850 when people were commenting on the urban heat island around the pioneer town of St. Louis (website 6). Consequently, the urban heat islands are warmer with smaller diurnal variations (website 6). With growing population and growing urban construction, all urban regions are always going to be significantly and progressively warmer than other rural regions. Moreover, these upward temperature trends are accelerating because of the exponential growth in population.
In fact, airports as well have similar heat islands. Thus, these huge paved runways soak up sunshine and also act like huge "Trombe" walls laying on the ground, keeping the locality warmer. Further, the enormous burning of gasoline also helps keep it warmer than the surrounding country. Mistakenly, there are currently a large number of surface temperature observations located at airports. Consequently, increased air traffic and larger airports cause these sites to warm up as well. As a result, skeptics argue that "doomsday" scientists must remove the "inaccurate" city and airport observations and bring the surface temperature recordings into better agreement before global warming can be properly assessed as an actual phenomenon (website 5).
Furthermore, many global warming skeptics maintain that global warming's temperature increase is only minimal. Some assert that since even the IPCC now predicts a global warming of only 1 to 3.5 degrees Celsius over the coming century the effects it will have on our climate will be too small to be noticeable (website 10) [see graph 3]. Thus, they argue that this small change, much less than the current daily temperature range for most major cities, is hardly a cause for concern (website 2). However, as I have mentioned earlier, such small temperature changes should not be taken lightly, for even minimal changes in temperature can have dire changes on our climate.
III. Change in Rainfall Precipitation
Changes in the pattern of rainfall precipitation has also occurred in relations to the increase in global warming. Consequently, global warming has actually dramatically altered the distribution of precipitation worldwide; thus, rainfall has been both simultaneously increased and decreased, but occurring in different areas. Evidently, some climate models have projected that winter precipitation in the United States will increase by as much as 15% while summer precipitation will decrease by 5 to10% by 2030 (website 3). The ultimate consequence is that this will hurt such industries as agriculture (website 3).
In some areas, global warming has actually decreased precipitation. Since the mid-1960s, average rainfall in the Sahel and much of the east and south of Africa has declined sharply. The past decade in southern Africa has been both the warmest and driest this century. The growing seasons of 1991-92 and 1994-95 were among the five driest years in the twentieth century, causing crop failures, water shortages, killing wildlife and threatening human health (website 3).
Ultimately, soil moisture will also be affected by such dramatic changing precipitation patterns. Furthermore, precipitation pattern changes will ultimate result in a more intense hydrological cycle, which is the exchange of water among the ocean, atmosphere, and land by such processes as evaporation, precipitation, surface runoff, and groundwater percolation, (Pinet, 1998). Based on a global warming of 1 to 3.5 degrees Celsius range over the next one hundred years, climate models forecast that both evaporation and precipitation will increase, as will the frequency of intense rainfalls (website 5). While some regions may become wetter, in others the net effect of an intensified hydrological cycle will be a loss of soil moisture. Some regions that are already drought-prone may suffer longer and more severe dry spells. Notably, scientific climate models anticipate seasonal shifts in precipitation patterns; ultimately, soil moisture will decline in some mid-latitude continental regions during the summer, while rain and snow will probably increase at high latitudes during the winter (website 5).
However, skeptics assert that precipitation will change only minimally and any such changes is not as destructive as many fear to be. They claim that although precipitation increases in some areas and decline in others, the ultimate repercussion is that it offsets any potential "calamities" (website 5). Moreover, they argue that climate models are still unable to make precise regional predictions. Thus, the hydrological cycle many scientists and climatologists use to explain global warming is far too complex to predict the future. Moreover, climatologists cannot just assume a notable change in precipitation as a consequence of global warming (if it exists at all), for the hydrological system also responds to other human activities such as deforestation, urbanization, and the over-use of water supplies (website 5). Thus, in order to fully analyze the true extent of the effects of global warming, scientists much consider these many other factors which might be the true culprit of a change in precipitation patterns rather than just "global warming" itself.
IV. More turbulent storms
There is steady consensus among scientists and global warming experts that global warming has caused more recent and frequent turbulent storms on Earth. However, they also agree that such storms occur on regionally (i.e isolated incidents) and thus global warming's effect on increased storms on a world-wide scale is not yet entirely conclusive (website 4). Regardless of whether its consequences are regional or global-scaled, global warming has indeed resulted in more frequent and more intense tropical cyclones in certain areas. Because these storms depend on a warm surface with unlimited moisture supply, they form only over oceans with a surface temperature of at least 26 degrees Celsius. Therefore, oceanographers and scientists often conclude that global warming will lead to increased ocean temperatures and, likely, more tropical storms (website 4).
Recent increased storm occurrences include hurricanes and cyclones, as well as a recently-studied El Nino. Hurricanes are tropical cyclones that originate over tropical oceans and that blow in a large spiral around a relatively calm centre or "eye" (Bernarde, 1992). Models developed by the Centre for Meteorology and Physical Oceanography at the Massachussetts Institute of Technology (MIT) reveal that the increased temperature caused by warming, has also increased the intensity of hurricanes (Bernarde, 1992). This is not a new phenomenon; historical records have shown that during periods of above-average sea-surface temperatures, the frequency of storms have also increased all over the world (Bernarde, 1992).
Tropical cyclones is but one variant of these turbulent storms and their impacts are not all negative. These storms, known as hurricanes in the Atlantic and as typhoons in the western North Pacific, can also do enormous damage to coastal areas and tropical islands. Nevertheless, as the climate warms, changes in tropical cyclone activity varies by region. Not all the consequences would be negative, for in an arid and infertile regions, the contribution of tropical cyclones to rainfall is crucial (website 4). One example is in northwest Australia, where 20 to 50 percent of the annual rainfall is associated with tropical cyclones. Notably, the damage done by a single powerful cyclone can be indisputably spectacular. For example, the August 1992 Hurricane Andrew killed 54 people, left 250,000 homeless and caused $30-billion worth of damage in the Caribbean and in the southeast coastal U.S (website 4).
Notwithstanding, global warming's effect on the oceans have nonetheless altered the characteristics of these storms. In fact, many scientists argue that global warming has caused the recent occurrence of El Ninos, an abnormal warming of the equatorial Pacific, in particular the Easter Pacific, which occurs every 3 to 8 years. Evidently, tropical oceans' temperatures were up to 0.75 degrees Celsius warmer during the 1980s than in the previous three decades. This appears to have affected the intensity and frequency of the largest single influence on tropical climate--a cyclical weather phenomenon called El Nino in the tropical Pacific Ocean. El Nino events typically occur every three or four years, when the winds and currents across the equatorial Pacific switch direction, pushing a pool of very warm water out east across the Pacific towards the Americas. After about nine months, the reverse currents falter and the system returns to its normal state (website 3).
Moreover, some scientists believe that global warming's link to El Nino's is quite evident. During June 1997, dramatic increases in water temperature were recorded in the Pacific Ocean, indicating that it may turn out to be the strongest El Nino this century (website 3). Ostensibly, two decades of frequent and intense El Nino events, coupled with a near-continuous warming of the tropical Pacific Ocean, is statistically a once-in-two thousand year occurrence (website 3).
Notwithstanding, skeptics argue that recent scientific research of climate models and historical data indicate that the relationship between global warming and increased global turbulent storms is far too simplistic. Other factors, such as atmospheric buoyancy, instabilities in the wind flow, and the differences in wind speed at various heights (vertical wind shear), also play a role in the storms' development (website 4). As a result, many dispute that the reliance on climate models have proved of limited use in predicting changes in cyclone activity. Part of the problem is that the simulations are not yet detailed enough to model the very intense inner core of a cyclone (website 4).
The historical data are only moderately more useful; regardless, they are also unreliable because they are often skewed. It has been impossible to establish a reliable global record of variability of tropical cyclones through the twentieth century because of changes in observing systems (such as the introduction of satellites in the late 1960s) and population changes in tropical areas (website 4). Moreover, we still do not understand what clearly triggers an El Nino; thus, global warming is but one of many possibilities (MacKay, 2000). Furthermore, from the ice core data we know, El Nino events have already occurred for at least the last 500 years, so they are nothing new to our ocean system (MacKay, 2000).
Analyses of historical data dealing with global warming and tropical storm patterns do not give a clear conclusion, for there are always "doomsday" reports and adamant skeptics. For instance, studies suggest that since the late 1980s, North Atlantic winter storm activity has been more extreme than it ever was in the previous century. Over the past few decades, there has also been a trend toward increasing winds and wave heights in the northern half of the North Atlantic Ocean (website 4). But in contrast, other investigation, particularly the Institute for Meteorology in Hamburg, Germany, found no evidence of changes in storm numbers in the North Sea. In fact, NOAA's Atlantic Oceanographic and Meteorological Laboratory has revealed that there is a decrease in the intensity of hurricanes, and the total number of hurricanes has also followed suit. The years 1991 through 1994 were extremely quiet in terms of the frequency of storms, hurricanes and strong hurricanes (website 4). Thus, as a result of such ambiguous reports, it is still premature to assume that global warming is the culprit for the recent rise and developments in turbulent storms. However, it is quite safe to conclude that global warming has certainly had some impact.
V. Conclusion and the "possible" Future
This essay has attempted to argue that global warming has indeed caused climate changes to occur on our planet. More significantly, this essay used three main effects caused by global warming: the increase of average temperature; changes in rainfall precipitation; and also the increase of turbulent storms. Additionally, this essay tried to supply both sides of the argument for and against the effects of global warming. Although there is a sturdy agreement among the scientists that global warming has indeed changed our climate, there is also a convincing argument that global warming's effects are minimal, if it exists at all.
However, in my personal opinion, it seems though people on Earth should take the careful route and try everything possible to reduce CO2 and other such culprits which cause global warming. The consequences of climate change is quite compelling that if the Earth continues its detrimental climate irregularities such as global warming the only consequence is pure catastrophe. Be it natural or man-induced, we should all try to reduce the enhance greenhouse effect as much as possible.
Sources Cited
Bernarde, Mevlin A. Global Warning. . . Global Warming. John Wiley & Sons: New York, 1992.
MacKay, Jennifer. "Global Warming: Parts 1 and 2." 2000. University of British Columbia.
Pinet, Paul R. Invitation to Oceanography. Jones and Bartlett Publishers: Sudbury, 1998.
(Website 1) http://www.edf.org/pubs/FactSheets/o_GW.html
(Website 2) http://www.edf.org/pubs/FactSheets/e_GWFact2.html
(Website 3) http://www.panda.org/climate_event/report.htm
(Website 4) http://www.sciam.com/0597issue/0597karl.html
(Website 5) http://www.unfccc.de/resource/iuckit/fact14.html
(Website 6) http://users.erols.com/dhoyt1/index.html
(Website 7) http://www.epa.gov/globalwarming/faq/moredetail.html#q1
(Website 9) http://www.newscientist.com/nsplus/insight/global/alaska.html
(Website 10) http://globalchange.org
(Website 11) http://www.usgcrp.gov/usgcrp
Graph
Average global surface temperatures have increased 0.6 to 1.2 degrees fahrenheits since the late nineteenth century. But more strikingly, the twentieth century's ten warmest years have all occurred within the last 15 years. Of these, 1998 was the warmest year on record
http://www.epa.gov/globalwarming/climate/index.html
Graph 2
http://www.globalchange.org/default.htm
Graph 3
http://www.usgcrp.gov/usgcr