"Sudden" has nothing to do with the greenhouse effect. As far as the amount of CO2 emitted, Canada contributes an insignificant amount on a global scale. If we reduce our emissions to zero, it wouldn't affect a thing, except make some people feel all warm and fuzzy.
Canada can, however, have a great impact in reducing global CO2 levels because of the oil sands, if a pipeline is built to China. If China uses our demonized oil instead of burning coal, that will have a huge impact on CO2 levels. The evil villain becomes the hero.