Climate is global and climate policy (if there is to be one) has to be international. Local emissions policies make no sense; they impose local costs with little if any local benefits. Even the Europeans' cap-and-trade program is not of an adequate global scale. Permit prices have been falling ("As carbon prices sink, unease rises") because local permit demand is limited. As a result, incentive effects to adopt cleaner technologies are muted.
It would function more like the textbook version if there was a single global cap-and-trade. But that will never happen. International unity on the issue only exists at the level of feel-good platitudes and communiques.
What to do? Natural gas is replacing coal in the U.S. The power plants that burn them will continue to get cleaner -- as they have been for many years. The many "doomsday" forecasts rest on assumptions of static technology. That assumption becomes sillier by the minute.