Greenie activist Jo Abbess has recently set out at length some details and evidence of “robust findings” in an IPCC report about global warming. The first such finding is:

Current atmospheric concentrations of CO2 and CH4, and their associated positive radiative forcing, far exceed those determined from ice core measurements spanning the last 650,000 years

Peter Ridley [peter.ridley@fsmail.net] noted that the abbess has a comments facility on her blog so valiantly submitted a comment in reply. Needless to say, however, the abbess has not published the comment. So I thought I would. It follows:

Has that method used for reconstructng past atmospheric compositions using air recovered from ice cores, which Professor Richard Alley refers to as the “Gold Standard”, been subjected to a proper assay showing that it is not in fact fools gold?

Why do I ask this? It is because I have not yet been able to find any worthwhile research providing convincing evidence that air “trapped” for hundreds and hundreds of years within ice retains unchanged the composition that existed at the time of initial capture. As I understand it that air is first “trapped” in snow as it forms and falls and is then retained within the increasingly densified ice as it is compresses beneath more falling snow.

As Jaworowski et al. have pointed out, most recently in 2007 at the time that the non-scientific AR4 SPM was issued – ahead of the finalised report upon which it was supposed to be based was written – there are numerous physical and chemical processes that distort the original composition.

Although scientists who regard those reconstructions as Alley does claim to take account of these processes there is one about which little if any worthwhile research seems to have been undertaken. This is the preferential fractionation of CO2 and CH4 into higher levels during the many years in which firn exists.

This fractionation arising from the smaller relative sizes of these gases compared with the major constituents, N2 and O2. The fractionation has the effect of increasing the concentration at higher levels in the firn at the expense of the lower levels, giving a false impression of lower concentrations levels of these smaller trace gases in earlier ice.

Perhaps you’d like to point to convincing evidence that this effect either does not take place or is properly accounted for in the attempts to reconstruct atmospheric composition in the past, especially pre-industrialisation.

Once we’ve properly covered that “robust finding” we should be able to address Robust Finding (4) quite quickly and move on to the next.

Posted by John Ray (M.A.; Ph.D.). For a daily critique of Leftist activities, see DISSECTING LEFTISM. To keep up with attacks on free speech see TONGUE-TIED. Also, don’t forget your daily roundup of pro-environment but anti-Greenie news and commentary at GREENIE WATCH . Email me here