Global Warming: Is It Caused by Nature or Mankind?

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Introduction

The greenhouse effect is a term that describes an increase of the average global temperature and is often associated with global warming which is the subject of great debate and concern worldwide. Although warnings about the human generated causes of an enhanced greenhouse effect and the subsequent catastrophic outcomes have been sounded for over 100 years, global warming has only recently become an important political matter. This discussion will first define the greenhouse effect then explain how naturally occurring and man-made gases affect it along with examples of the consequences of these forces. Greenhouse gasses are produced by nature and man but the excess produced by man is causing the earth too warm. Most scientists worldwide accept the sufficient evidence that suggests global warming is already well underway and cannot be reversed anytime soon. The question before us is, are we stewards of our earth and will we preserve it for future generations?

Greenhouse Gases

How it Works

Essentially, the greenhouse effect functions in the following manner. When sunlight pierces the atmosphere and hits the earths surface, not all of the suns solar energy is absorbed. Approximately a third of it is reflected back into space. Specific atmospheric gases serve in much the same way as does the glass of a greenhouse, thus the terminology. These gases allow sunlight to penetrate then trap some of the solar energy which heats the earth (Breuer, 1980). It is a delicate balance and because these greenhouse gases have been artificially augmented by man-made sources, more build up in the atmosphere has occurred thus trapping more of the suns energy and reflecting less back in to space. This occurrence is causing the earth to warm.

Carbon Dioxide

Carbon Dioxide (CO₂) is the most prevalent of the greenhouse gases. Trees absorb CO₂ and when they die, CO₂ is restored to the atmosphere. The clearing of forests by mass burning, which is happening at a phenomenal rate in the tropical rain forests, is decreasing the amount of CO₂ that is absorbed and increasing the amount that is added to the atmosphere. CO₂ supplies about half of the total gases that create the greenhouse effect (Breuer, 1980). Although deforestation is contributing heavily to the excess of CO₂ in the atmosphere, a larger portion is caused by the burning of fossil fuels such as oil and coal.

Fossil fuels are burned by factories, vehicles and electricity-producing power plants to name a few sources. The vast majority of this excessive fuel consumption and its poisonous, pollutant and greenhouse-enhancing byproducts are located in the U.S., Europe and Russia (Breuer, 1980). Other greenhouse gases include methane, which is released when vegetation is burned during land clearing, during oil exploration activities and the coal-mining process; chlorofluorocarbons (CFCs), which is the substance that cools refrigerators and provides the propulsion in aerosol cans and nitrous oxide (N₂O) which is the lesser cause of CO₂ (Breuer, 1980). It is generated from both man-made and natural processes. It is estimated that man-made influences represents about half of the CO₂ output.

What and Who Are to Blame

The rising levels of carbon dioxide (CO₂) in the atmosphere are becoming increasingly disconcerting. The concentrations of CO₂ in the air around 1860 before the effects of industrialization were felt, is assumed to have been about 290 parts per million (ppm). In the hundred years and more since then, the concentration has increased by about 10 percent. (Breuer, 1980, p. 67). Eighty percent of the worlds population accounts for just 35 percent of CO₂ emissions while the United States and Soviet Union combined are responsible for generating half. Worldwide, carbon dioxide emissions are increasing by four percent a year. (Miller, 1990, p. 450). Motor vehicles are a major cause of air pollution as is fuel burned for the heating of homes and powering industry along with the toxins emitted from stacks at coal-burning power plants. Vehicles produce high levels of carbon monoxides (CO) and a major source of hydrocarbons (HC) and nitrogen oxides (NOx), whereas, fuel combustion in stationary sources is the dominant source of sulfur dioxide (SO₂) (Breuer, 1980, p. 70).

A Delicate Balance

If the balance between the CO₂ levels in the ocean and atmosphere is disturbed by interjecting increasing amounts of CO₂, the oceans would continually absorb higher concentrations than it does naturally. The subsequent warming ocean waters are less effective in their ability to absorb CO₂ and when the oceans can no longer keep pace with the intrusion of this naturally equalized cycle, and then more CO₂ will remain in the atmosphere. Increasing the amount of CO₂ in the atmosphere is expected to result in a warming of the Earths surface accelerating the greenhouse effect. Currently carbon dioxide is responsible for 57 percent of the global warming trend. Nitrogen oxides contribute most of the atmospheric contaminants (Miller, 1990, p. 498).

The Effects of Climate Change

Unbalanced Results

Future scenarios for greenhouse gas quantities, especially regarding CO₂ and CH₄, are hardly an exact known when attempting to project future climate changes. Formulating the net greenhouse effect is complex because of its associations to supplementary aspects of energy cycles. However, the period of time that records have been kept is sufficient now so as to make comparative trends regarding the effects of climate change. One of the problems regarding to measuring global warming is that the phenomenon is not occurring in an obviously uniform and steady manner. Many areas of the world, in fact most, experience a wide variation of temperature and climactic effects from year to year (Wunderlich & Kohler, 2001). Thus the feedback from studies are vulnerable to challenges made by a minority of scientists, politicians and other citizens who have, for whatever reason, an agenda that compels them to rebuke the overwhelming evidence that man-made causes are accelerating the greenhouse effect.

Denial

Although science has identified a radically changing climate as the result of human activity, many will not admit it to themselves. A parallel here is trying to link lung cancer to smoking. There are always some people who smoke who do not get lung cancer, and some who get lung cancer who do not smoke. Yet the evidence is compelling that there is a link. Still there are always people who do not want to believe and justify their beliefs by feeding on the legitimate uncertainties that exist (Trenberth 1997). This is, essentially, the same faction of those who think that change is inevitable, that our advancing technologies will enable us to adapt to climate change as it happens. In other words just ignore the problem by continuing to pollute for economic reasons and the problem will just go away. That doesnt work for any other type of problem and wont with this one either.

The Thermohaline Effect

One would have to wonder what enormous problems this will cause not only to people and property but to the health of the global economy as a whole. Entire sections of various countries will be forced to abandon their homes and businesses. The process will be a slow and torturous one. Scientists also worry about the effects of a changing climate on the Gulf Stream, a massive ocean current which acts to warm the continent of Europe. Ocean currents transport large amounts of heat around the world: climatologists call it thermohaline circulation (THC) (Climate Crisis 2000). If it slows down or moves further south as a result of Greenland melting, Europe could end up with a climate more like that of present-day Greenland. A BBC-produced television program documented recently that Greenland is in fact melting at an alarming rate providing photographic evidence taken in the 1970s in contrast to photographs taken in the present day. This leads one to wonder if forces act to warm the climate yet at the same time cool it too, will these things balance each other to then have a neutral effect? Wishful thinking does no harm. Yes it does. Thats what much of the world leaders have done for thirty years. Thats how long we have known about the greenhouse effect, why it happened and what the results would be, but we have done little to avoid this calamity.

Harm to Crops

There are many scenarios that should be examined from a multiple of perspectives when contemplating the development of strategies for managing transformations in the global climate. One effect of global warming is that although trees could greatly benefit from an increase of CO₂, which is the prime means by which photosynthesis is processed, the long term effect to trees is as yet unclear (Hanson et al, 2000). Generally, trees can be divided into either C₃ or C₄ plants. In both groups, net CO₂ assimilation occurs in the chloroplast through the reductive pentose phosphate (RPP) pathway, or the Calvin Cycle (Monson, Edwards & Ku, 1984: 563). In the short term, forests and agricultural products will probably benefit from the increased fertilization and water efficiency effects of higher CO₂concentrations. In the long term, the regional distribution of crops will be altered, thus requiring significant regional adaptations. Many studies have been performed; however, all they have proved thus far is that sufficient information is still not known regarding specifically how atmospheric changes may affect these innumerable components that play a role in a healthy eco-system.

Melting Ice Caps

The effects of melting snow caps and the resulting rise of sea levels have been well documented. In An Inconvenient Truth Gore systematically describes the perils to civilization potentially caused by global warming. The recent surge in land-based ice melting is alarming because of the implications for global sea levels. Land-based ice is ice propped up above sea level. If it melts, the runoff increases sea levels, if a big chunk of land ice were to melt, world sea levels could rise by up to 20 feet (Beyerstein, 2006). Gore displays a series of maps simulating the effect such a sea level rise on coastal cities in several low-lying regions of the world. Sea levels would rise by another 20 feet if a chunk of Greenland melted.

If sea levels rose by 20 to 40 feet, rain patterns would radically change and flooding would inundate many regions while others experienced droughts on an unprecedented scale. With Katrinas devastating effects on the Gulf Coast fresh in our memories, Gore notes that weve seen the effects of 200,000 refugees and to then imagine the effects of a hundred million (Chutry Experiment, 2006). Gore then demonstrates that rising water levels and the massive human misery it would cause is not the worst effect of melting ice. As Greenland melts, cold water mixes into the warm Gulf Stream currents in the Atlantic which acts to keep Europe warmer than other regions of similar latitude. If this warmer current turns cold, as it would if half of Greenland melted, a present-day ice age would envelope all of Europe. Rising temperatures also give rise to more violent storms by increasing evaporation from the seas (Chutry Experiment, 2006).

Lesser Known Effects

Other effects of global warming are known but not as universally. A reduction of snow cover in addition to lake and sea ice will have dire consequences for locations at higher latitudes and lower elevations, especially in the winter and spring months. At increased temperatures, the atmospheric water vapor and resulting precipitation will be proportionately higher (Wunderlich & Kohler, 2001). Cloud compositions will change which will amplify the greenhouse effect. The increased levels of precipitation because of the warming at the Polar Regions will increase the effect. Shifting vegetation patterns, types and regional variations, will cause major human adaptations, the degree to which is open to speculation.

The elevated evaporation rate will hasten the drying effect of soil subsequent to rainfall which will result in drier conditions in many regions. Places that presently suffer through periodic drought conditions in the warmer months will be hardest hit. The more rapid water recycling rate will result in heavier rainfall amounts and the number of extreme rainfall events. Higher rainfall rates will cause increased tropical storm intensity in addition to the warmer temperatures. Hurricanes may be even more frequent and intense than presently predicted. As horrific as this near-future scenario is, it remains the land masses that will suffer the greatest changes as a result of the greenhouse effect. Temperatures are expected to increase more rapidly over land compared to oceans because of the oceans higher heat capacity and because it can transfer more of the trapped heat to the atmosphere by evaporation. Over land, the warming has been and is expected to continue to be larger during nighttime than during daytime (Wunderlich & Kohler, 2001).

Conclusion

If the past 30 years are any indication, then the answer is no. Noticeable effects of global warming are fairly insignificant right now to the average person, but its effects are unquestionably growing in scale. If the population of the planet were to immediately discontinue polluting the air with carbon dioxide emissions, climate changes would still continue long into the future. This is because of the long lifetimes of carbon dioxide (centuries) and other greenhouse gases in the atmosphere and because of the thermal inertia of the oceans. The oceans overturn very slowly and take hundreds of years to adjust fully to changes, so that manifestations of changes that have already occurred are not yet fully seen (Trenberth 1997).

It is vitally important that the people of the world realize that we have set in motion an experiment on planet Earth which we cannot simply turn off because we finally realized the dire consequences. If we injure the planet in this selfish, cataclysmic method, we kill future generations of humankind. Agriculture activity, land masses and the very air we breathe will suffer a radical change from the effects of global warming, but to what degree? The projected rate of climate change is very alarming to many scientists but not as much to politicians as this topic isnt as high on the political agenda as some others. It seems that the world leaders have no sense of urgency about them regarding global warming. They place great importance on the popular items of the day such as education, crime, economics and war so as to be reelected but if they dont address this issue, there will be nothing to politicize in the future as we will have no future. Reasonable people of all backgrounds and nationalities agree that if CO₂ emissions are not greatly reduced and soon, the resulting greenhouse effect will alter the climate and possibly the sustainability of humankind.

Works Cited

Breuer, Georg. Air in Danger: Ecological Perspectives of the Atmosphere. New York: Cambridge University Press. (1980). Cited in Air Pollution Causes and Effects by Tom Socha. Web.

Beyerstein, Lindsay. An Inconvenient Truth: Review. Magikthese. (2006). Web.

(The) Chutry Experiment. An Inconvenient Truth. (2006). Web.

Climate Crisis: All Change in the UK? BBC News. (2000). Web.

Hansen, J., M. Sato, R. Ruedy, A. Lacis, and V. Oinas. Global Warming in the Twenty-first Century: An Alternative Scenario. Proceedings of the National Academy of Sciences. Vol. 97, pp. 9875-9880. (2000).

Miller, G. Tyler. Living in the Environment: An Introduction to Environmental Science. Belmont: Wadsworth. (1990). Cited in Air Pollution Causes and Effects by Tom Socha. Web.

Monson, Russell K.; Edwards, Gerald E.; Ku, Maurice S.B. C₃-C₄ Intermediate Photosynthesis in Plants. Bioscience. Vol. 34, N. 9, pp. 563-566 + 577-574. (1984).

Trenberth, Kevin E. Global Warming: Its Happening. National Center for Atmospheric Research. (1997). Web.

Wunderlich, Gooloo S.; Kohler, Peter O. Improving the Quality of Long-Term Care. The National Academies Press. p.18. (2001).

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