It has also been argued, looking at the past geological record, that ice ages follow periods of heightened temperatures. So we might be looking at a cold period a few hundreds years from now (thumbsuck timeline guess on my part) anyway. 

Another thing to consider: A winter induced by blocking the rays of the sun will affect plant life and likely freeze vast areas of the oceans - these are the two main systems that dilute and remove CO2 from the atmosphere. If their capacities are reduced, a winter as you mention would just delay the warming and possibly make it worse once temperatures start to rise again. Notwithstanding that such a winter would devastate our civilization, we would have to produce even less CO2 than the lower standards currently called for. Simply put: int he long term it could make things much worse.

A winter of this sort is not a normal winter as we know it. It will cause wide-scale ecological changes that could arguably change the world even more than global warming would. At the very least it would just mean exchanging one cataclysm for another.