In his Nobel lecture (reprinted in the June issue of the American Economic Review), William Nordhaus concludes that we should focus on four goals:

First, people around the world need to understand and accept … Those who understand the issue must speak up and debate contrarians who spread false and tendentious reasoning. …

Second, nations must establish policies that raise the price of CO2 and other greenhouse-gas emissions. …

Moreover, we need to ensure that actions are global and not just national or local. … The best hope for effective coordination is a climate club, which is a coalition of nations that commit to strong steps to reduce emissions along with mechanisms to penalize countries who do not participate. …

Finally, … [d]eveloping economical low-carbon technologies will lower the cost of achieving our climate goals. Moreover, if other policies fail, low-carbon technologies are the last refuge—short of the salvage therapy of geoengineering—for achieving our climate goals or limiting the damage.