A correction, I have read the Kump & Pollard paper [Amplification of Cretaceous Warmth by Biological Cloud Feedbacks -- Kump and Pollard 320 (5873): 195 -- Science], which I discussed a little yesterday.
I looked at it again briefly, and the main things to add are (1) their experiment is what I thought, which is that they artificially change the effective droplet radius. This is fine, as it is artificially prescribed anyway. And (2) they provide a reference for the assertion that DMS is the primary non-anthropogenic CCN. That reference is actually a perspective in Science by Andreae(DOI: 10.1126/science.1136529). I've just read that piece, which is interesting, but I feel is deeply flawed. Rather than pick it apart, let me just say that my primary concern is that it does not seem to give a broad overview of the current measurements, but cherry picks a few studies that may or may not be designed well enough to get at the points being made. In the end, the firm conclusion is that pre-human aerosol distributions, specifically CCN-sized aerosol, is very poorly understood, and that no good way to guess the concentrations has been devised yet. Good points, and that is all I have to say of that article.
More on CCN later though, as this is a good area to explore!