Climate change: Conflict of observational science, theory, and politics: Discussion

Abstract

Gerhard (2004) argues that our reasoning on the causes of climate change should be guided by observational science, instead of by results derived from computer models. Given that the nature and balance of the controls of the Earth's climate remain uncertain, this appears to be a sound suggestion. On the strength of his own reading of recent observational science, Gerhard adheres to the view set out by the AAPG Ad Hoc Committee on Global Climate Issues in its 1999 annual report: “Because no tool is available to test the supposition of human-induced climate change and the range of natural variability is so great, there is no discernible human influence on global climate at this time.” (Gerhard and Hanson, 2000, p. 466). Gerhard (2004, p. 1219) now asks: “Why is it that we spend so much time and resources trying to prove a theory of greenhouse gas climate control instead of testing the hypothesis?” A contrary view is expressed in a position paper of the Stratigraphy Commission of the Geological Society (London) (Zalasiewicz et al., 2004, p. 1): “We find that the evidence for human-induced climate change is now persuasive, and the need for direct action compelling.” Oreskes (2004, p. 1686) cites evidence that such a view is representative of a notable consensus in the refereed scientific literature, and that “all major scientific bodies in the United States whose members' expertise bears directly on the matter have issued similar statements.” Where does that leave Gerhard and the AAPG? That question can finally be answered when this particular scientific dispute is agreed by all rational parties to have been settled by the weight of observational evidence, instead of by majority voting or social pressures. This particular debate on climate change is of major economic and political significance as well as …