Thursday, April 12, 2007

CO2 and temperature:which is cause and which is effect?

One of the joys of tracking an issue across the blogosphere is that you become acquainted with other commentators and engaged minds through their frequent and excellent contribution to posts. One such thinker is Lubos Motl, who's posts I have read on several sites concerning both climate change and the theory of anthropogenic global warming (AGW). Lubos runs his own blog which he calls The Reference Frame.

Here is a recent post from Lubos on correlation, causation and the actual relationship between carbon dioxide and temperature in the historical record. And here is a similar discussion by Tim Patterson that reaches this conclusion:

  • ...the geologic record clearly shows us that there really is little correlation between CO2 levels and temperature. Although CO2 can have a minor influence on global temperature the effect is minimal and short lived as this cycle sits on top of the much larger water cycle, which is what truly controls global temperatures. The water cycle is in turn primarily influenced by natural celestial cycles and trends.

As discussed by Lubos, advocates of AGW variously dismiss these facts, offer extended and often convoluted alternative explanations for them and/or even deny that they are relevant observed data. Moreover, many of the more zealous pro-AGW blogs suggest that bringing these facts to your attention is the real act of denial -- somehow AGW has reached a status of axiomatic truth, so inviolate that any questioning has to be an act of scientific treason, denial or worse...the paid opinion of big oil.

It occurs to me that placing these facts before you is neither heresy nor denial, but a simple exposition of observed data with the obvious corollary: how can anyone view these facts and still seek to infer a cause and effect relationship without also positing the possibility that an alternative explanation may be self-evident. At what point do you cease to explain away the data that don't fit your hypothesis and just abandon it in favour of a different, more robust explanation?

As this post illustrates, the point of abandonment may occur when advocacy is over-extended and alienates those objective scientists who seek to support the AGW hypothesis but not at the expense of their intellectual integrity.