Climate model sensitivity to a doubling of atmospheric CO2 is intrinsic to the model itself and has nothing to do with what aerosol forcings are. (skepticalscience.com)
The policies desired by green advocates become much less likely to be adopted if lower sensitivity is credible (and modeled sensitivity less so). (climateaudit.org)
Hence the NH / SH ratio does not make a good quantitative test of modeled sensitivity in my opinion. (realclimate.org)