Environmental Effects of Increased Atmospheric Carbon Dioxide


Global Warming Petition Project – January, 1998

This a rather old text. It was one of the first to come out and say that the CO2 effects are being over emphasized and the data is not conclusive. Most people that have followed this subject for several years have read and understood this text but the topic of climate change is gaining increased popularity. If you have only recently started reading about this subject, it is important that you familiarize yourself with this early text.

The Petition Project has thousands of signatories. This is one of the reason that so many people are up in arms against Vice President Gore when he makes broad statements that science has unanimously come to the conclusion that the world is in store for really bad things to happen. The most common comeback is the these thousands of signatories are fake, kooks, or they are all on big oil’s payroll (or all three).

I find that generalization to be abhorrent. Surely, many of these people are learned people that have investigated the issues and have deemed the current state of information to have them conclude that the world is not going to end. When multiple people disagree, rather than name calling, we should agree on a standard of evidence that would be conclusive. This is billion dollar problem – why is it so hard to spend some effort to set up a standard that everyone can agree on?

A review of the research literature concerning the environmental consequences of increased levels of atmospheric carbon dioxide leads to the conclusion that increases during the 20th Century have produced no deleterious effects upon global weather, climate, or temperature. Increased carbon dioxide has, however, markedly increased plant growth rates. Predictions of harmful climatic effects due to future increases in minor greenhouse gases like CO2 are in error and do not conform to current experimental knowledge.

The empirical evidence actual measurements of Earth’s temperature shows no man-made warming trend. Indeed, over the past two decades, when CO2 levels have been at their highest, global average temperatures have actually cooled slightly.

To be sure, CO2 levels have increased substantially since the Industrial Revolution, and are expected to continue doing so. It is reasonable to believe that humans have been responsible for much of this increase. But the effect on the environment is likely to be benign.

The current increase in carbon dioxide follows a 300-year warming trend: Surface and atmospheric temperatures have been recovering from an unusually cold period known as the Little Ice Age. The observed increases are of a magnitude that can, for example, be explained by oceans giving off gases naturally as temperatures rise. Indeed, recent carbon dioxide rises have shown a tendency to follow rather than lead global temperature increases.

There is, however, a widely believed hypothesis that the 3 Gt C per year rise in atmospheric carbon dioxide is the result of the 5.5 Gt C per year release of carbon dioxide from human activities. This hypothesis is reasonable, since the magnitudes of human release and atmospheric rise are comparable, and the atmospheric rise has occurred contemporaneously with the increase in production of CO2 from human activities since the Industrial Revolution.

For example, about 300 years ago, the Earth was experiencing the ”Little Ice Age.” It had descended into this relatively cool period from a warm interval about 1,000 years ago known as the ”Medieval Climate Optimum.” During the Medieval Climate Optimum, temperatures were warm enough to allow the colonization of Greenland. These colonies were abandoned after the onset of colder temperatures. For the past 300 years, global temperatures have been gradually recovering. As shown in figure 2, they are still a little below the average for the past 3,000 years.

When an increase in CO2 increases the radiative input to the atmosphere, how and in which direction does the atmosphere respond? Hypotheses about this response differ and are schematically shown in figure 9. Without the greenhouse effect, the Earth would be about 14 ºC cooler (25). The radiative contribution of doubling atmospheric CO2 is minor, but this radiative greenhouse effect is treated quite differently by different climate hypotheses. The hypotheses that the IPCC has chosen to adopt predict that the effect of CO2 is amplified by the atmosphere (especially water vapor) to produce a large temperature increase. Other hypotheses, shown as hypothesis 2, predict the opposite that the atmospheric response will counteract the CO2 increase and result in insignificant changes in global temperature (25-27). The empirical evidence of figures 5-7 favors hypothesis 2. While CO2 has increased substantially, the large temperature increase predicted by the IPCC models has not occurred.

In effect, an experiment has been performed on the Earth during the past half-century an experiment that includes all of the complex factors and feedback effects that determine the Earth’s temperature and climate. Since 1940, atmospheric GHGs have risen substantially. Yet atmospheric temperatures have not risen. In fact, during the 19 years with the highest atmospheric levels of CO2 and other GHGs, temperatures have fallen.

The reasons for this failure of the computer climate models are subjects of scientific debate. For example, water vapor is the largest contributor to the overall greenhouse effect. It has been suggested that the computer climate models treat feedbacks related to water vapor incorrectly.

At present, science does not have comprehensive quantitative knowledge about the Earth’s atmosphere. Very few of the relevant parameters are known with enough rigor to permit reliable theoretical calculations. Each hypothesis must be judged by empirical results. The global warming hypothesis has been thoroughly evaluated. It does not agree with the data and is, therefore, not validated.

There is much more to this paper.  I have only grabbed a few portions of the first half of it.  I encourage you to read the full posting, look at their references, and then decide if they may have some valid concerns about the current worry for the end of the world.

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