Some scientific questions about absolute certainty of global warming

Tue, 03/06/2007 - 5:26pm
By: The Citizen

By Mark W. Hendrickson, Ph.D.

For those who believe in the global warming (GW) theory (i.e., that human activity is heating the planet to dangerous levels) the ace of trump has been played. On Groundhog Day 2007, the U.N.’s Intergovernmental Panel on Climate Change (IPCC) — the ultimate authority in the eyes of GW disciples — declared with 90 percent (i.e., virtual) certainty that the theory is true.

Pardon me if I don’t genuflect. The IPCC has been irretrievably politicized. This is self-evident in light of the IPCC’s current stunt of calling for radical action now, months before it publishes its scientific research.

Such impropriety is rather typical of the IPCC. In 1995, the body of its report stated explicitly the scientific conclusion that there was no definitive link between GW and human behavior, yet the policymakers’ summary — the part that the media latched onto — directly contradicted what the scientists had written.

That political recommendations take precedence over scientific findings is made explicit in Appendix A to the Principles Governing IPCC Work, which states, “Changes ... made after acceptance by the Working Group or the Panel shall be those necessary to ensure consistency with the Summary for Policymakers or the Overview Chapter.”

The reflex response of GW true believers to what I just wrote is to suspect me of being a lackey for Big Oil. Well, I’m not. And neither are the 17,000-plus scientists who have signed a petition in opposition to GW orthodoxy. (See

As an economist, I sympathize with the meteorologist-climatologist fraternity. None of us predicts the future accurately, because there are too many variables and unknowns.

Unfortunately, in the case of GW, the public is obsessed with a single variable — carbon dioxide. Millions of people believe that increases in the concentration of carbon dioxide in our atmosphere will heat the planet.

Whether Earth will warm or cool this century, I know not, but I can safely say that the mechanistic theory “the more carbon dioxide, the warmer the Earth” is not only simplistic, it is fallacious. It certainly cannot be a scientific law, because the climate frequently acts contrary to that relationship.

Examples are legion; here are three:

1. Most of the warming in the 20th century occurred in the first half, while most of the increase of carbon dioxide happened in the second half.

2. According to Stephen Schneider, a leading GW proponent, throughout Earth’s history, warmer periods have preceded periods of increased carbon dioxide in the atmosphere; thus, given the cyclical nature of climate change, increased carbon dioxide historically has been followed by cooler periods.

3. According to paleoclimatologist professor Tim Patterson, the coolest period on Earth in the last half-billion years occurred when concentrations of carbon dioxide were more than 10 times what they are today (levels attained, incidentally, long before the advent of homo sapiens).

What can explain such phenomena? One factor is that carbon dioxide isn’t the primary greenhouse gas. Carbon dioxide causes somewhere between 9 and 26 percent of the greenhouse effect; water vapor accounts for most of it.

Water vapor alone, then, can more than offset carbon dioxide’s impact. (By the way, since humankind’s carbon dioxide emissions comprise 5 percent or less of the total — far less than oceans, volcanoes and termites — that means that the human contribution to any greenhouse effect is minuscule.)

Furthermore, even when greenhouse gasses are abundant, increased cloud cover may reflect the sun’s energy back into space rather than trapping it in the Earth’s atmosphere, thereby cooling the planet.

Our understanding of cloud formation is far from complete, but apparently cosmic rays play a significant role. I’m not sure how Congress could regulate those.

More fundamentally, the greenhouse effect isn’t even the primary driver of GW. Some scientists calculate that three-fourths of the fluctuations in Earth’s temperature are caused by changes in solar activity. The sun, too, lies beyond the control of Congress.

Speaking of solar activity, when you hear the familiar refrain that the most recent decade was “the warmest in history,” remember that they are disingenuously defining “history” as that infinitesimal sliver of geological time since Uncle Sam started keeping temperature records in the 1870s, and understand that Earth should be warmer now, since a low point in the solar cycle made the 19th century unusually cool.

Like King Canute, who vainly commanded the waves to halt, we delude ourselves if we think we have the knowledge or power to control Earth’s climate. Rather than squander our wealth on futile attempts to fine-tune the ever-changing climate, our leaders should enact wealth-generating policies that will provide the wherewithal to cope with the myriad changes and challenges confronting us in this amazing world.

[Dr. Mark W. Hendrickson is an economist and contributing scholar with The Center for Vision and Values at Grove City (Penn.) College.]

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