One of the fundamentals of public economics is that the free market -the interplay of individual supply and demand decisions mediated through the price systemwill result in the provision of less than the collectively optimal level of public goods. Thus, the state has a role to play, either in producing the good directly (the traditional approach) or at least in arranging for its production by a private firm (the increasingly popular 'outsourcing' strategy). Examples of national public goods run from police protection to national security to financial regulation to museums and artistic ensembles. But some goods are quite clearly public at the global level. The classic case is greenhouse gas emission control.