While there is general consensus the fact that humans contribute some amount to global warming, there is no consensus on how much we have caused or feedbacks related to the climate system. It is for this reason that any tax on carbon is an unnecessary strain on our economy given our immediate information.
Please consider the costs taxing carbon, introducing tariffs, and eliminating subsidies all at the same time. Commodities prices could nearly double as the cost of goods transport skyrockets.
The weather anomalies of 2012 are not related to climate change. The US meteorological society only recognizes 30 year climactic trends, and the current climate trend is deceleration of rising temperatures.
Consider that science on impacts is very divergent and there is no consensus yet.