Negative feedbacks

Here is the sort of negative feedback in climate that makes sense from a process perspective:

http://www.agu.org/pubs/crossref/2010/2009GL041320.shtml

Note how it is regional and dynamical, and not likely to persist.  So, this is providing a source of internal variability in the climate system, where not all regions experience the same warming from the increased forcing from CO2.  It is this sort of internal variability in the climate system that skeptics ignore because they want everything to be linear. 

Also note that in a colder drier atmosphere, this feedback might not be so effective since cloud formation would be suppressed.  Reduced cloud populations are inferred in the paleo record from the increase in dust during glacial epochs. 

I think that's part of it.  It is probably also that the air is so dry over Antarctica that the increase of CCN doesn't do much of anything because their isn't enough water vapor to condense most of the time anyway.  If you plotted the forcing, CCN and specific humidity as a function of latitude you would likely find the maximum in the negative forcing corresponded to the region where water vapor was still high and CCN was increasing. 

Skeptics can point to this as a negative feedback, but more likely they will point to this as another example of "fiddling" with mechanisms to "explain" why the Antarctic hasn't warmed as much as the Arctic.  Any attempt to add understanding to climate science is viewed by skeptics as a cover-up of what they assume to be the basic fact that CO2 has no effect on global climate.  And then, it was is truly an awesome display of cognitive dissonance, they then claim that scientists are suppressing understanding of climate science.  I have yet to meet a climate skeptic capable of flexible thought, the smart ones are completely rigid in believing whatever misconception they have is the only way to view the science, and the dumb ones are so laughably ignorant it isn't worth the time trying to correct them.