While the hump shaped relationship depicted in Figure 1.5 seems to hold across a wide range of pollutants-from sulfur dioxide to lead concentrations and water quality-carbon dioxide emissions are an important exception, rising steadily with higher income levels. Given that increased atmospheric carbon dioxide concentrations are a cause of global warming, this should be of serious concern. The solution to the problem, however, is probably not to roll back the trade liberalization efforts that have fostered economic growth and globalization, but to get the nations of the world to agree to tougher standards on limiting carbon emissions. Although UN sponsored talks have had this as a central aim since the 1992 Earth Summit in Rio de Janeiro, there has been little success in moving toward the ambitious goals for reducing carbon emissions laid down in the Earth Summit and subsequent talks in Kyoto, Japan in part because the largest emitter of carbon dioxide, the United States, has refused to sign global agreements that it claims would unreasonably retard economic growth. In addition, the United States, whose carbon emissions are increasing at an alarming rate, has so far shown little appetite to adapt tighter pollutions controls.