Examiner Bio Climate Change 101: Does carbon dioxide cause global warming?
December 30, 11:24 AMLA Public Policy ExaminerWilliam WestmillerPrevious 6 comments S. Fred Singer is an American atmospheric physicist, Professor Emeritus of environmental sciences at the University of Virginia, specializing in planetary science, global warming, ozone depletion, and other global environmental issues. He was a Special Advisor on space developments to President Eisenhower and the first Director of the National Weather Satellite Service Center. He is President of the non-profit Science & Environmental Policy Project, author of Hot Talk Cold Science: Global Warming's Unfinished Debate, Unstoppable Global Warming (NY Times Bestseller), and editor of Nature, Not Human Activity, Rules the Climate.
Examiner: Does carbon dioxide cause global warming?
Singer: Carbon dioxide is a trace gas that doesn't produce any heat of its own, but it does act like a blanket. Most solar rays pass through it, warming the earth. Most heat radiated from earth is absorbed and then re-emitted by the CO2 or, more importantly, by water vapor. That's why CO2 is called a "greenhouse gas", even though it doesn't actually retain heat in exactly that same way that a sealed greenhouse does. Nevertheless, it is certainly one factor that affects the amount of retained heat on earth and therefore the dominant temperature.
In theory, any warming caused by CO2 will be most evident in the upper troposphere, where most commercial airliners fly, particularly over the tropics. If atmospheric CO2 were the primary cause of increased global temperatures, the increase would be even more pronounced at those altitudes. The most accurate measurements indicated that, over the last three decades, there has only been slight warming. So, it's very hard to make the case that CO2 is a primary factor. [Reference] [Reference]
More important, the Vostok ice core studies demonstrate that increased CO2 concentrations follow the millennial temperature increases by about a thousand years. That's been true for hundreds of thousands of years. The common sense view is that warming causes more CO2, not that higher CO2 causes warming. Of course, there are fudge factors. We don't know exactly how fast CO2 is absorbed - we call it 'sequestered' - in the oceans during temperature declines, nor do we know how fast it is released when atmospheric temperatures rise. What we don't know far exceeds what we do know.
What people should know is that CO2 is only one of a half-dozen greenhouse gases [GHG] in the atmosphere. Most of them have a stronger effect on warming than CO2 and the overwhelming GHG is simple water vapor. Almost all of the alarming computer models have to assume some positive feedback effect, so that CO2 increases cause more water vapor, multiplying the greenhouse effect, in order to portray CO2 as a causative effect of warming. Those computer models have thousands of related assumptions that haven't been scientifically demonstrated by actual, confirmed testing.
So, to answer your question, yes: CO2 concentrations certainly have some effect on global temperatures. It's just that the predicted effects aren't evident and CO2 alone may be a relatively insignificant factor in warming.
Examiner: Isn't CO2 a pollutant, as designated by the Environmental Protection Agency?
Singer: The EPA was given a very broad mandate by Congress, granting them control over any substance that they believed might cause harm. They simply accepted the U.N. conclusions that anthropogenic CO2 causes warming and all warming causes harm. Neither conclusion is defensible, but the agency has accepted them as the scientific consensus, so they want to impose restrictions on CO2 emissions. Consensus is totally irrelevant to science, but it's very important to politics. Ask Galileo.
We learned in grade school that CO2 is absolutely essential to all life on earth. If it didn't exist, all plants would die and every animal would eventually starve to death, including every human. Calling CO2 a pollutant is silly, or at least a very bad euphemism. If the EPA were to strictly follow its mandate, it would punish every human being that exhaled.
It is absolutely true that CO2 can be dangerous to your health, but only if concentrations are extremely high, more than 20 times the present level. We have to get a significant amount of plain old oxygen in every breath we take. But, you don't have to worry about too much CO2 fizz in your soda, seltzer, or champagne.
Examiner: Hasn't the burning of fossil fuels by humans produced a lot of CO2 over the past century?
Singer: Yes, but you have to put that in context. While natural sources of CO2 are twenty times greater than human sources, the observed rise in the past 150 years is almost all anthropogenic, mostly from burning of fossil fuels, from cement manufacture, and from land clearing. The influence of all CO2 is guesstimated at less than 10 percent of the total greenhouse effect, with water vapor the main GHG.
Now, put those greenhouse effects into the context of all the other temperature factors, like changes in solar activity, cloud cover, and ocean circulation. The human impact on warming becomes inconsequential.
Given that the "fingerprint" of CO2 warming has not been detected, we should discount the influence of human fossil fuel combustion to practically zero.
Beyond that cursory evaluation, there are many confounding factors in the analysis of CO2 influence on warming. As global temperatures increase, some CO2 dissolved in the oceans is released into the atmosphere. At the same time, increased temperatures and CO2 encourage plant growth, which increases the absorption of CO2 from the atmosphere. Earth's climate is a complex and chaotic system. We only understand a few of the interactive components that influence temperature. There is no scientific certainty about all the causative factors, much less a consensus that humans have caused recent warming.
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