From Nic Lewis's article:

Table 8.7 shows that the best estimate for total aerosol RF (RF_ari+aci) has fallen from −1.2 W/m² to −0.7 W/m² since AR4, largely due to a reduction in RF_aci, the uncertainty band for which has also been hugely reduced. It gives a higher figure, −0.9 W/m², for AF_ari+aci. However, −0.9 W/m² is not what the observations indicate: it is a composite of observational, GCM-simulation/aerosol model derived, and inverse estimates.

From the Media Matters article.

With regard to aerosols: Abraham told Media Matters: "it is very clear [they] have a cooling impact," adding, "I don't know of any reputable scientist that would dispute that." Boston University's Robert Kaufmann, lead author of a 2011 sulfur emissions study, agreed:

I know of no evidence that would suggest that the temperature effect of sulfur emissions are small.  This conclusion is totally at odds with my peer reviewed publication in the area, which indicate that sulfur emissions have a significant effect on temperature.

It's now up on Think Progress. No mention of Lewis.

Stranger and stranger.