National Oceanic and Atmospheric Administration, this time studying the temperature in the oceans, reported that heat in the deep ocean had been increasing at a surprising rate and that it contained far more heat energy than previously thought. According to the lead scientist, Sydney Levitus, “The data filled a missing piece of the global warming puzzle, suddenly scientists realized that the deep ocean was a heat-sink of sorts, and that the ocean was the place where much of the predicted heat of global warming was stored.” The data they got from the deep ocean was fed into two of the world's most sophisticated computer generated climate models. The results they got back are evidence that human activity is partly responsible for current climate warming. Both models strongly suggest that the extra heat in the oceans can't be explained by natural variability.
Another piece of key evidence, to support human induced climate changes, come from scientists comparing the temperatures in the southern and northern hemispheres, where most of the human activity such as burning fossil fuels and cutting down forests, with the southern hemisphere. The study is based on the fact “…that past values for temperature in the southern hemisphere help us predict temperature in the northern hemisphere better than just looking at past values for temperature in the northern hemisphere," says Kaufmann. Temperature in the northern hemisphere is in a statistical sense dependent on temperature in the southern hemisphere, but the reverse, however, is not true because of the weather patterns seem to work this way. So using these facts and analysing records of temperature in southern and northern hemisphere, from 1865 to 1999, the scientists have determined that there have been variations in the climate patterns which cannot be explained by natural occurrence. The changes, according to the scientists, can only have taken place due to human activities such as deforestation, burning oil, natural gas, and coal, emitting chlorofluorocarbons and various other activities which release greenhouse gases.
The cornerstone of the argument for human-induced global warming is the climate models generated by supercomputers. These models are generally called “general circulation models” and their purpose is to simulate many features of the climate. Many of the environmental groups along with their experts claim that these models, which are manually programmed by humans, can give us a reasonably accurate prediction of what the temperature and climate will look like in the future. Most importantly, they claim that the computers are programmed to ignore natural interference, thus showing changes in temperature only due to human activity.
There is significant evidence to support the argument put forward by the people who think that global warming is fully, if not, mostly human induced. The other side think otherwise and although they are in the minority they still have a pretty good case. Now I want to look at the arguments from the people who think global warming is fully, if not, mostly natural. Firstly, many of the leading scientists believe that the gases we are emitting are not enough to cause climate change. According to a report published by the 90 billion tons of carbon dioxide annually circulates between the earth's ocean and the atmosphere, and another 60 billion tons exchange between the vegetation and the atmosphere. We can compare this data to the man-made emissions which added up to about 5 to 6 billion tons per year, the natural sources would then account for more than 95 percent of all atmospheric carbon dioxide.
According to professor of geography, Robert Essenhigh, “At 6 billion tons, humans are then responsible for a comparatively small amount, less than 5 percent, of atmospheric carbon dioxide,” he said. “And if nature is the source of the rest of the carbon dioxide, then it is difficult to see that man-made carbon dioxide can be driving the rising temperatures. In fact, I don't believe it does.” Some scientists believe that the human contribution to carbon dioxide in the atmosphere, however small, can upset the earth's environmental balance. Essenhigh has proved that, mathematically, the hypothesis is inadequate and lacks evidence to support the theory.
Another study done by Cambridge University geology department has found that global temperature has been oscillating (going up and down) steadily, with an average rising gradually over the last one million years, long before any human industry began to release carbon dioxide into the atmosphere. The study also showed that during the last 100,000 years, the temperature rose more significantly than it had done before. The explanation put forward points out that, today we have reached near peak in the current cycle that started about a million years ago. Some scientists predict that the global warming will reach its peak by the next 10 to 20 years and then the earth will supposedly cool down, starting a new ice age.
One of the key areas of debate is do with the climate models, with many researchers question the validity of the predictions given by the computer generated models. The programmers themselves admit that the climate models are in fact too complicated and are not accurate enough to provide reliable forecasts of how the climate may change and several models often produce contradictory results. They only use these climate models because for the time being all they have are these to predict future climate changes. Professor Collin Millard says, “The global general circulation models which simulate significant amounts of human-induced warming are incorrectly structured to give this positive feedback loop. Their internal model assumptions are thus not realistic.”
William Grey, a correspondent and researcher, along with his team of researchers have worked for more than 10 years to investigate natural forces which affect our climate. They examined countless reports, studies and statistical data. They have come to the conclusion that the subject of global warming has been “…extended and grossly exaggerated and misused by those wishing to make gain from the exploitation of ignorance on this subject.” They also mention that the governments of developed countries, the media and scientists who are willing to bend their objectivity to obtain government grants for research on this topic are all to blame.
That’s all the information I have decided to use and a closer look reveals gaps in substantiating the evidence. The research taking place today has not reached the stage where we can be a hundred percent certain about the results. Even though this essay assumes that global warming is taking place, the question of whether global warming is taking place is still a valid one. There is evidence from NASA scientist John Christy to maintain this argument. While compiling satellite data extending back to 1979 (which is not very long, in global terms), Christy found that temperature measurements in the Earth's upper atmosphere showed a cooling of two degrees Fahrenheit over the past two decades. Because most scientists, who specialize in this field, have presumed that global warming would affect all layers of the atmosphere in a uniform way, Christy's research has been a foundation of the arguments for those who disagree with reports on the severity or even the existence of global warming.
Before I can come to a solid concluding argument, we must evaluate the evidence. As I mentioned, there are gaps and doubts in the evidence. This means it is very hard to make accurate judgments and predictions. I want to first of all analyze the evidence from the point of view of the people who think global warming is human induced; much of the evidence comes from the computer generated climate models. Even if these models are not fully accurate, virtually all the published predictions about climate change are based on the results from these models. We have to assume that there is some basis of evidence in these models or these climate models would have been discarded a long time ago. The numerous studies and reports are also equally reliable, even if most of the studies fail to take into account the natural climate cycle and tend to concentrate only on the increases in greenhouse gases; they prove to have some truth nonetheless.
Meanwhile, the arguments to support global warming is being natural, for the most part is based on dismissing the arguments and evidence from the other side. Looking at the history of earth, the facts show that there have been several ice ages and years of extreme heat. What the earth is experiencing now could be just another one of these natural cycles.
The majority of the people, simply just accept the idea that global warming is human induced. I personally started writing this essay thinking there was no doubt humans were solely responsible for global warming, but now almost at the end of it having second thoughts. I must admit the evidence I found for global warming being natural is quite strong and possibly even better than the other side. This question is particularly difficult to answer because there seems to be a lot of circumstantial evidence and there needs to be a lot of research done into this field. For the time being we must take whatever steps necessary to reduce the impact of global warming. The impacts are another important question to consider; unfortunately this essay will not answer that question.
So the big question is whether global warming human induced or is it a natural phenomenon? Well, there is significant evidence and strong arguments from both sides. It is hard to single out only one cause for global warming. During the past 100 years the temperature has increased so much that it would never be possible for just natural forces to cause the increase. So the truth is, the temperature is rising naturally and it would have done so with or without human interference. The temperature increases, however, would have been at a lot slower rate, but because of human interference the rate of temperature increase is a lot higher. The conclusion I have come to is that both human activities and natural forces are responsible for global warming. The only question now is which of the two is more influential in bringing about global warming, that is if they are not equally responsible.
Appendix
Figure 1
Figure 2
Endnotes
EPA website, 2002
see appendix (figure 1) for graph showing the temperature
Encarta Encyclopedia 2002, 2001
see appendix (figure 2) for diagram explaining greenhouse effect.
The Natural Science Foundation is the premier science research facility in the United States. Most of the funding comes from the government.
The National Oceanic and Atmospheric Administration is the organisation in the United States which takes measurements from the oceans and atmosphere. It is funded by the government.
Albert Kaufmann is the lead scientist in this study
The IPCC was set by the United Nations in order to combat and reduce impact of global warming
Robert Essenhigh is a professor of geography at Boston University and is an expert on global warming
Millard is a well known expert on global warming and has written several articles on the subject
William grey works as a reporter for the BBC. He has published many books and in the last decade he published some of the key findings, which support global warming as being natural.
Tyler, 1999
Bibliography
Works cited
Donellan, Craig. Climate change. Cambridge: Independence, 1998
Gray, William. “Viewpoint: Get off warming bandwagon.” BBC website (16 November, 2000). <> [18 april 2003]
Encarta Encyclopedia 2002. CD-ROM. 2001.
Essenhigh, Robert Interview by Deepak Mathews. Chat Room. 13 April, 2003.
EPA: EPA global warming site.
< http://yosemite.epa.gov/oar/globalwarming.nsf/content/index.html> [24 April, 2003]
Encarta Encyclopedia 2002. CD-ROM. 2001.
Tyler, Hillary. Global warming: The controversies. London: Milton Keynes, 1999
Works consulted
Encyclopedia Britannica 2001. CD-ROM. 2001