People who value real science are of course willing to ask questions when the facts don't fit the theory.
Where is the test of the hypothesis that sulfates are indeed responsible for the lack of warming? In this paper, it's simply "modeled-in" as it fits the data well. That's correlation, not causation.
There is very little exchange of air between the northern and southern hemispheres, and basic climate science shows that most sulfates from China will rain out before they get across the thermal equator. In fact, there is a great deal of literature out there published by luminaries like the Department of Energy's Ben Santer and NASA's James Hansen claiming relative cooling of the northern hemisphere from sulfates, compared to the southern.
So, if it is indeed sulfates cooling the warming, given that there is no net change in global temperature, then the northern hemisphere should be cooling since 1998 (the first year in Kaufmann's paper) while the southern warms. Here are the sad facts:
The opposite is occurring. Why this test was not performed eludes me. Perhaps that is because it provides yet another piece of evidence supporting the hypothesis that we have simply overstated the sensitivity of surface temperature to changes in carbon dioxide.
It's been 30 years since the alarmists first started claiming the sky was falling and global warming would doom us all.
None of their predictions have come true and the skeptic stance that natural variation and the influence of the sun were much more realistic explanations of observed changes in climate has been borne out.