Below is the abstract of the manuscript I have been preparing. A draft is available via the contact form above if you are interested in helping out with feedback. Comments from the mysterious Dr Jones that prompted this manuscript are listed below.
Update: Now Submitted to Journal of Geophysical Research.
Recent Data Show No Weakening of the Walker
David R.B. Stockwell and Anthony Cox
Abstract: Various authors have examined the strength of the equatorial Pacific overturning known as the Walker Circulation in both climate models and observations, attributing a generalized weakening to anthropogenic global warming. Here we review the analysis in Power and Smith  using updated Southern Oscillation Index (SOI) and NINO sea surface temperature indices. We find no significant long-term changes in the indices, although the SOI appears to have recovered from an anomalously low period from 1976 to 1998. The increasing sea surface temperature in the NINO4 region is not significant, nor representative of other NINO regions. The findings of a weakening Walker circulation appear to be premature, and the corresponding climate model projections cannot be substantiated at this time. The reports of weakening of horizontal atmospheric circulation in climate models should be regarded as an inconsistency and not as an indicator of anthropogenic climate change.
I want to acknowledge the contribution of Dr Jones, who’s comments appearing across a number of blogs including NM over a period of a few days played a part in prompting this manuscript. (I know who Dr Jones is, but will preserve his anonymity) Here are a selection of gems:
Dr Jones: You mix changes in variability and changes means. The slowing down of the Walker circulation is an observed fact and can happen regardless of whether you get more, less or the same number of El Nino/La Nina events. A shift towards a weakened Walker circulation is required by basic physics otherwise the tropical atmosphere will quickly rain itself out. The slow down leads to a shift towards a more negative mean SOI which has clearly been seen seen over the last century (http://www.agu.org/journals/gl/gl0718/2007GL030…).
I have shown you just one paper – there are many more – in the peer reviewed literature which deal with this very issue.
Dr Jones: Under global warming evaporation increases (about) linearly in temperature but water holding capacity increases exponentially in temperature. This relationship forces a slow down in the Walker circulation which will lead to a tendency for more negative SOI values with warmer global temperatures. See Vol 441|4 May 2006|doi:10.1038/nature04744.
Climate has long ago moved from the blind application of statistics. Your 9% mixes up correlation with causation (though even so is correct in showing that global warming is not caused by ENSO).
Dr Jones: So if summer is hotter than winter that disproves global warming?
You really have no idea do you.
ANDREW REPLIES: Readers, what is scary about this troll-like response – so angrilly missing the point that AP made a blatantly false claim – is that it comes from one of the leading warming â€œexpertsâ€ in the country. That should tell you plenty. His fury is directed not at the scaremonger, but the debunker.
I appreciate when experts do visit the blogs to provide their perspective, as it always seems to send things off in an interesting direction.