There are, I guess, two broad themes running through this topic: the effect of pollution on the Earth; the effect of pollution on people and upon other innocent animals, of which we are not part.
In the case of the former, any decrease in the white coverage of this oblate spheroid we call home will result in an unavoidable amount of solar heat being absorbed. If you question that - as photographers - it amazes me. If photographic experience isn't enough, I'd advise a trip to Spain where the vast majority of cars bought are white. No, it's not a colour that matches the fiery Latin temperament at all well, but it does serve to keep the people inside the cars from boiling in summer. So, conserve the north and south regions as well as is possible. If you live in some deserts you experience roasting days followed by freezing nights, illustrating the fact that where there is no cloud cover, the extremes of light (heating/cooling)are magnified. So, should we welcome perpetual clouds? Hardly: everything on the surface of Earth needs adequate sunlight to survive, including us. We don't need extended rainy periods, which our current excesses are encouraging, unless we all prepare for a sole diet of rice with rice. Oh, possibly with some remaining fish, too, if there was any left for you to buy, Chef!
Dealing with the population, on the other hand, pollution from exhausts of cars, aircraft, factories, power stations, all of those things that emit it, has never been shown to have a beneficial side. I remember well the days in the UK when coal was used for domestic heating. The results of that were terrible, with huge problems for movement of vehicles and even walking people. Not being able to see one's feet is not a geat exaggeration. That vanished almost the moment that controls were introduced; yes, fog still arrives as usual, but that is moisture, not lung-destroying carbon and sulphur chemistry. I can remember schools being closed early to save kids from the dangers of being killed by lost vehicles, and even when I was working it wasn't unknown for some of our departments to be let out early because of weather. Apart from the dangers to people, those disruptions affect profit.
In conclusion, it seems fairly obvious to me that even if a sound argument could be engineered to disclaim the effects of global warming on life, there is no sound reason to deny that lowering the pollution levels drastically helps people live healthier lives. As for smoking... no, that takes me into the health-care debate and I might find myself stating that smokers should be denied state medical aid along with habitual drunks.
;-)
Rob