Comment In February 2007 issue Of The Bulletin Of The American Meteorological Society On Attribution Based On Model and Observation Intercomparisons

There was a very interesting Comment published in the February 2007 issue of the Bulletin of the American Meteorological Society. It is entitled

A. T. J. de Laat, 2007: Mixing Politics and Science in Testing the Hypothesis That Greenhouse Warming is Causing a Global Increase in Hurricane Intensity Bulletin of the American Meteorological Society Volume 88, Issue 2 (February 2007) pp. 251–252 DOI: 10.1175/BAMS-88-2-251 [pages
251-252].

The paper is discussing recent claims on the attribution of hurricane intensity to global warming, but the discussion by A.T.De Laat is applicable to the conclusions based on any result of the multi-decadal global model predictions reported in the 2007 IPCC Statement for Policymakers.

Excerpts from the paper read,

“The line of reasoning here is that natural factors alone cannot explain the observed twentieth-century temperature variations, while including greenhouse
gases does. The logical fallacy is the “fallacy of false dilemma/either–or fallacy,â€? that is, the number of alternatives are (un)intentionally restricted, thereby omitting relevant alternatives from consideration (Haskins 2006).

“That global twentieth-century temperature variations can be explained by using a simple model merely points to a certain consistency between this model or climate model simulations and observations. Furthermore, the fact that the late-twentieth-century warming is unexplained by two factors (solar variations and aerosols) and can be explained by including a third factor (greenhouse gases) does not prove that greenhouse gases are the cause; it just points to a missing process in this model. In fact, this whole line of reasoning does not prove the existence of global warming; it is merely consistent with it. As an example, it is still debated whether or not land surface temperature changes during the twentieth century are affected by anthropogenic non–greenhouse gas processes and whether or not these processes affect surface temperatures on a global scale (Christy et al. 2006; Kalnay et al.2006; de Laat and Maurellis 2006).

There is a risk associated with this line of reasoning in that it suggests that understanding temperature variations of the climate system as a whole is very simple and completely understood, all one has to consider is the amount of incoming and outgoing radiation by changes in atmospheric absorbers and reflectors. Notwithstanding the fact that temperature is not a conserved quantity in any physical system, and thus is not the best metric to study energy within the climate system, it also suggests that other processes and nonlinear behavior of the climate system are either nonexistent or do not affect (decadal and global) temperature variations. Presenting climate science this way oversimplifies the complexity of the climate system and possibly overstates our current understanding. Furthermore, this simple model is of limited use to climate scientists other than to very qualitatively explain—not understand—climate variability. By suggesting that climate science is simple and straightforward, the model surely does not help bridge the gap between climate science and the general public.â€?

The entire Comment is worth reading.