What would be crippling is a cold year. A cold Winter last year already showed some of these effects. If this Winter were to have major cold and snow over all the major population centres of the NH, i.e., China, Western Europe and Eastern USA, and then we were to have a cold Spring, a cold and wet Summer and Autumn then there'd be problems. We'd see rocketing fuel and food prices due to a shortened growing season and a real possibility of food riots in poorer countries.
I guess we're lucky to have global warming rather than global cooling.