I asked the following question on April 12 the April 2018 blog:
"How much do sulfates and aerosols affect temperature? I am thinking that incoming sunlight is reflected back into space by these substances before it reaches low altitudes thereby preventing some warming. Just how much effect they have is what I am not sure about."
A response from Al Roger on April 14:
"And mentioned up-thread, the SO2 emissions are very short-lived so drops in their negative forcing would quickly contribute a significant boost to AGW were they cut in a hurry. However, the cutting will not be immediate and so any significant boost could theoretically be mitigated by cuts in N2O or CH4 forcing as well as the more slowly falling CO2 forcing (when emissions are cut enough for that to begin)."
So it sounds a lot more complicated than "the effect of SO2 is 2-4C so I just say 3C of additional warming locked in."
So I am still trying to wrap my brain around this issue and understand it better. Looking at worldwide air quality for the past several years
http://aqicn.org/map/world/ it appears China has significantly reduced air pollution and as a result has reduced aerosols and sulfur dioxide. It is spring so China's air is cleaner than during the winter but air pollution levels are down significantly during all the seasons as best I can tell.