You have presented a far more insightful answer. My comment was intended to be glib rebuttal to a comment that implied that it was a quick easy fix.
Soot: Course particulates wash out fairly fast. Fine particulates in the upper atmosphere act to cool the surface. Fine particulates near the surface. Don't know. The latest plant at Genesee (my neighbor) has no visible plume at all. They really are quite good at cleaning up their emissions.
C02: I think the IR that can be blocked by CO2 is mostly blocked now. I suspect that further CO2 releases will have an increasingly marginal effect. Still some. Beyond my knowledge to calculate.
Thermal: Overall a 1 GW solar photoelectic plant will be a worse thermal source than at 1 GW coal plant -- at the location. The solar plant will locally put in about 9 GW of thermal (figureing 10% efficient cells) The Coal plant about 2 GW thermal (figuring 33% thermal efficiency) If you take into account the light that would be absorbed anyway by the land the solar plant is on, that 9 GW is much smaller. Comes out to pretty much of a wash either way. But the coal plant is adding energy that hasn't been seen for a long time.
This post shows that the issue is complicated. All the posential solutions have difficulties. At present my take on the potential answers:
1. If we are going to burn coal, burn it in solid carbon fuel cells. This has the advantage of much greater efficiencies, and the CO2 is already separated for sequesterization. This technology is still experimental.
2. If we are going to do solar, solar thermal shows more promise, with the potential to store enough heat for night time operations. Photo solar has promise for off grid use, but currently, battery technology is a sticking point. (The thought of recycling a household's worth of lead acid batteries every three years for every household is daunting.)
Both technologies require specific climates to be efficient. (But see Germany. If ever there was a place where solor shouldn't work...)
3. Wind for suitable sites mixes better with agricultural, pastoral, and recreational use than does solar. Of the completely renewable sources, I think it is cheaper per generated watt hour.
4. High altitude wind power is an interesting concept that avoids most of the intermittency problems.
5. If EEStor's batacitor is real and comes to market it will change the entire picture, both for stationary and mobile energy use.
6. Nuclear may be part of the solution. Frankly I would prefer to have a nuclear reactor as a neighbor than the 2.5 GW coal-thermal plant that I have now. (And I mean neighbor-- Its mine starts 1 mile from my house.)