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The Role of Models in the CO2 Emissions Reduction Debate
Volume 6, Number 44: 29 October 2003

Based on testimony presented at a hearing of the Commerce, Science & Transportation Committee of the U.S. Senate on 1 Oct 2003 dealing with The Case for Climate Change Action, which was chaired by Senator John McCain of our home state of Arizona, our Editorials of 8 Oct 2003, 15 Oct 2003 and 22 Oct 2003 examine, respectively, the roles of religion, the insurance industry and science in the contentious debate over what to do, or not do, about the ongoing rise in the air's CO2 content.  In this editorial, we continue our analysis of what occurred at that hearing by examining the role of mathematical models, based on the testimony that was presented there by Dr. T.M.L. Wigley of the National Center for Atmospheric Research.

With respect to mathematical models of earth's climate system that are designed to be run on high-speed computers, Dr. Wigley declares in his written testimony that the case for taking action to mitigate what he claims to be human-induced changes in climate "rests on the credibility of these models."  Hence, he attempts to provide that credibility via a "comparison of observed and model-simulated changes."  This he does by "showing" that "models simulate temperature changes over the past 100+ years with considerable fidelity provided they are driven by observed changes in both natural forcing agents and anthropogenic factors," after which he concludes that "natural forcing alone cannot explain the past record."

This philosophy is most interesting, for it presumes we know the identity of all natural forcing factors and their diverse behaviors and magnitudes, which we must, if we are to correctly model the real world of nature.  And it is made even more interesting, providing an illuminating light on the window of Wigley's mind, by his forthright admission that we lack this essential knowledge.

Consider, for example, his statement that current state-of-the-art climate models do not include "the hypothesized amplification of solar forcing through the effects of cosmic rays, partly because there is no credible physical basis for this amplification."  How does Wigley know - for he states it as a fact - that there is indeed "no credible physical basis for this amplification"?  He may well believe such; but he cannot know it.  In fact, the elucidation of this "physical basis," which is currently hypothesized to be the potential interaction of the solar wind with cosmic rays and the consequences of this interaction for the creation of low clouds and their impact on near-surface air temperature (see Cosmic Rays in our Subject Index), may well lie just around the corner of time, so to speak, waiting to become the headline of tomorrow's newspapers and the lead story of the evening news on television.  To believe otherwise about all things postulated, as well as yet undiscovered, is to truly put one's head in the sand and say to those still seeking light and knowledge, "Stop, I know all I need to know, my ignorance is sufficient for the task at hand."

Clearly, however, one can readily forgive Wigley and others of his persuasion for not including this particular natural forcing factor in their models at the present time, because both its behavior and magnitude currently are unknown, making proper inclusion all but impossible.  But that forgiveness cannot be extended to his claim that working with only those factors of which we do have a good understanding is sufficient to prove that "natural forcing alone cannot explain the past record."  This conclusion simply does not follow, especially when the behaviors and magnitudes of numerous identifiable natural forcing factors remain unknown and, hence, are not included in today's best climate models, or when the discovery of as-yet-unidentified but potentially significant natural forcing factors remains a distinct possibility, as it surely does.

Who is there, in fact, that truly believes we currently know everything we need to know about what Wigley himself describes as "the many complexities and interactions of the climate system" in sufficient detail to accurately, or even in half-baked fashion, predict the course of earth's near-surface air temperature over the coming century?  Fools and politicians come to mind, as in the case of the Senate committee hearing that prompted our string of Editorials; but sincere seekers of truth should not.  It is a well known fact, for example, that one can get the right answer to a mathematical problem by any number of wrong procedures or mistakes, so that a close correspondence between observation and simulation, as in the case of the earth's near-surface air temperature trend of the past century, proves nothing.

In view of these obvious facts, it is truly astounding that Wigley goes on to insist that the warming of the planet over the past century - simply because it is consistent with model simulations - "can only be explained if one includes anthropogenic factors as part of the cause."  It is equally astounding that he claims that "anthropogenic forcing effects must be considered in order to explain the observations."  These statements are absurd and an affront to all logic, yet he and others continue to make them ? again and again ? and again.

Come on, Senator McCain, you're smarter than that.  Or does something else drive you to endorse such intellectual rubbish?

Sherwood, Keith and Craig Idso