The "Air Pollution Management" Newsletter

June 2008
No. 362

Global Warming Catastrophe

The debate over global warming is likely to continue with no major impact on a mercury control program. Regardless of the facts, we are likely to be continually bombarded with doomsday predictions. These are unlikely to persuade rate payers that a tripling of their electricity rates is justified. However, if some actual catastrophe were linked to warming, then there could be some abrupt change in public attitude. Despite the news stories which would indicate the likelihood of such a catastrophe, the odds are just as great for a warming catastrophe in the next fifteen years as they are for one from meteors.

One of the scenarios is for rapid loss of ice and rise in sea levels. Most scientists agree that any rise will be very gradual. Others even question whether there will be any rise.


“Global warming is not causing any significant retreat of polar ice caps, despite claims to the contrary in some media reports”, says James M. Taylor, senior fellow for environment policy at The Heartland Institute. “Although Arctic Sea ice last summer reached its minimum extent since satellites began measuring the ice in 1979, NASA scientists have discovered the sea ice retreated due to variable local wind patterns rather than global warming. Moreover, the ice re-formed at a record pace last fall. In the Southern Hemisphere, Antarctic Sea ice is at its greatest extent in recorded history. The majority of Antarctica is in a prolonged cold spell and has been accumulating snow and ice for decades.”


There are many aspects of global warming. One relates to the increases in CO2 levels. Is this harmful or beneficial? Do CO2 increases improve plant growth or do they hurt it? Do CO2 increases cause global warming or is it the other way around? Research has shown that in most cases rate of plant growth under otherwise identical growing conditions is directly related to carbon dioxide concentration. The amount of carbon dioxide a plant requires to grow may vary from plant to plant, but tests show that most plants will stop growing when the CO2 level decreases below 150 ppm. Even at 220 ppm, a slow-down in plant growth is significantly noticeable. Colorado State University did research on growing carnations in greenhouses. CO2 levels to 550 ppm produced an obvious increase in yield (over 30 percent), but the greatest benefits were earlier flowering (up to two weeks) with an increased percentage of dry matter. There is a very well organized website on CO2 science. There are detailed summaries and links to studies on various crops.


The conclusion is that nearly all agricultural crops respond to increases in the air's CO2 content by exhibiting increases in photosynthesis and biomass production, as well as their ability to deal with various environmental stresses.


You can search directly on the history of CO2 levels and find the following:  When the earth was in its infancy, some four-and-a half billion years ago, it is believed that the atmosphere was predominantly composed of carbon dioxide, which would have put its CO2 concentration, in terms of the units most commonly used today, at something on the order of 1,000,000 ppm. Ever since, the CO2 content of the air (in the mean) has been dropping.


By 500 million years ago, in fact, the atmosphere's CO2 concentration is estimated to have fallen to only 20 times more than it is today, or something on the order of 7,500 ppm, and by 300 million years ago, it had declined to close to the air's current CO2 concentration of 370 ppm, after which it rose to about five times where it now stands at 220 million years before present. Then, during the middle Eocene, some 43 million years ago, the atmospheric CO2 concentration is estimated to have dropped to a mean value of approximately 385 while between 25 to 9 million years ago, it is believed to have varied between 180 and 290 ppm. This latter concentration range is essentially the same range over which the air's CO2 concentration oscillated during the 100,000-year glacial cycles of the past 420,000 years.


With the inception of the industrial revolution, however, the air's CO2 content once again began an upward surge that has now taken it to the 370 ppm level, with the promise of significantly higher values still to come. In addition to its variation over geologic time, the atmosphere's CO2 concentration exhibits a strong seasonal variation. It declines when the terrestrial vegetation of the Northern Hemisphere awakens from the dormancy of winter and begins to grow in the spring, thereby extracting great quantities of CO2 from the air; and it rises in the fall and winter, when much of the biomass produced over the summer dies and decomposes, releasing great quantities of CO2 back to the atmosphere.


Will the ongoing rise in the air's CO2 concentration lead to catastrophic global warming? Observations of historical changes in atmospheric CO2 concentration and air temperature suggest that it is climate change that drives changes in the air's CO2 content and not vice versa. In a study of the global warmings that signaled the demise of the last three ice ages, it was found that air temperature always rose first, followed by an increase in atmospheric CO2 some 400 to 1000 years later. For all of the glacial inceptions of the past half-million years, air temperature consistently dropped before the air's CO2 content did, and that the CO2 decreases lagged the temperature decreases by several thousand years. In addition, the multiple-degree-Centigrade rapid warmings and subsequent slower coolings that occurred over the course of the start-and-stop demise of the last great ice age are typically credited with causing the minor CO2 concentration changes that followed them. There are a number of other studies that demonstrate a complete uncoupling of atmospheric CO2 and air temperature during periods of significant climate. Hence, there are no historical analogues for CO2-induced climate change, but there are many examples of climate change-induced CO2 variations.

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