Recent Data Show no Weakening of the Walker Circulation

Various authors have examined the strength of the equatorial Pacific over-turning known as the Walker Circulation in both climate models and obser-vations, attributing a generalized weakening to anthropogenic global warm-ing. Here we review the analysis in Power and Smith [2007] using updated Southern Oscillation Index (SOI) and NINO sea surface temperature in-dices. 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 corre-sponding 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.