A letter from a reader about The case against 'emissions as usual'

July 22, 2007:

In the Letters column of the April 4 issue, S. Fred Singer *48 puts forth another variant on his standard set of oft-repeated arguments against the evidence for anthropogenically driven global warming, present and future. I first met Dr. Singer over 40 years ago, when his field of specialization was cosmic-ray physics. Over the intervening decades, he has not become known for any ongoing research in atmospheric modeling, climate change, or related topics. He did, however, take a stand against the banning of ozone-destroying chlorofluorocarbons in the 1970s and 80s, much like his present stand against control of CO2 emissions. He remains one of a relative handful of reasonably qualified scientists, though not one with any significant record of climate research, who continues to maintain an "emissions as usual" position.

He takes to task two earlier letter writers to PAW for citing a "non-existent scientific consensus on anthropogenic global warming – ignoring the deep split in the climate community." I suppose there is an equally "deep split" in beliefs between those who espouse a flat earth and the rest of us, as well as a lack of consensus on the evidence. That doesn't make the flat-earthers right, and Dr. Singer's claims don't make him right. Dr. Singer does keep repeating the pre-determined strategy of the coal and oil companies to claim against all fact that there is a "deep split" among climate scientists over the causes of global warming. The hope is that if the public believes that a "deep split" exists, they won't believe either side and so will not support regulation of CO2 emissions and other energy-saving or climate-saving measures.

The fundamental physics of carbon dioxide makes it a strong absorber of infrared radiation (given off by all warm objects, including the Earth). Not even Dr. Singer denies that fact. More CO2 in the atmosphere means more absorption or blockage of infrared radiation given off by the Earth. This trapping effect causes the Earth to become warmer. Warmer bodies (including the atmosphere) emit proportionally more infrared radiation, until a new equilibrium temperature is reached where outgoing radiation balances incoming absorbed solar radiation. A good analogy would be to put on a winter overcoat on a sunny day in July. Your body temperature will rise until increased panting and perspiration allow you to reach a new (and less comfortable) equilibrium temperature.

Dr. Singer introduces a lot of diversionary digressions and arm-flapping in his letter to PAW, but does not and cannot deny the facts outlined above. He would say it is not as trivial as I have stated because of what are called "feedback effects." Skeptics cite only the so-called negative feedbacks, which can help mitigate the warming effect, at least for a while – things like increased evaporation of water into a warmer atmosphere that should cause more cloud cover, in turn resulting in more reflection of incoming sunlight, thus countering the CO2 trapping effect. But we now know (Dr. Singer often cites outdated and disproven propositions) that how clouds behave depends on how high they are and how thick they are – they, along with the increased water vapor itself, can trap outgoing infrared radiation to a greater extent than the reflective effect.

Arriving at an "accurate" prediction of how hot the Earth will get and how long it will take is thus not a simple matter, but no rational scientist will argue that more CO2 must trap more outgoing radiation and thus warm the Earth and atmosphere. Whatever the feedback effects – positive or negative – they will only kick in to operation due to that warming, and the new equilibrium will be warmer than the old would have been as long as more CO2 remains in the atmosphere. How many readers of PAW want to run this experiment, remembering that, as oft noted, we have only one planet with which to experiment?

All this has little or nothing to do with other variations in climate over time, some of which are well understood and some of which are not. An overwhelming consensus of that part of the scientific community that makes a study of climate and the atmosphere holds that the warming effects of anthropogenically increasing CO2 are now larger than any other ongoing climate cycles – positive or negative – that we may be simultaneously experiencing. One might argue that were we headed into another full-blown ice age, releasing lots of CO2 into the atmosphere could be a reasonable countermeasure. But we are not headed that way, and continuing "business as usual" is both irresponsible and extremely uneconomical, a point now being grasped by American businesses as well as the public. Perhaps someday even Dr. Singer will come to recognize this "inconvenient truth."

(I have been engaged in atmospheric research for the past 30-plus years, first on the issue of ozone depletion by chlorofluorocarbons, and more recently on general problems of atmospheric circulation, chemistry, and climate change.)

Department of Physics and Astronomy
Stony Brook University
Stony Brook, N.Y.


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