In recent years the United States has accounted for about 21 percent of the world's greenhouse gas emissions. China comes in second at about 15 percent. While many countries have stabilized their greenhouse gas levels, emissions from both nations, but especially China, are growing rapidly. Current projections suggest that by 2025 total emissions from the United States will increase by about one-third. By that year, China's emissions are expected roughly to double.... It follows that if an international agreement requires reductions, China and the United States will have to bear the brunt of the expense.
the biggest losers from greenhouse gas pollution are likely to be India and Africa. Some of the most detailed, careful and influential projections have been made by Yale University's William Nordhaus and Joseph Boyer. Nordhaus and Boyer show that in terms of human health and agricultural loss, India and Africa are by far the most vulnerable regions on Earth. Because of an anticipated increase in malaria, Africa will probably be hit especially hard, and India is expected to suffer a large increase in premature deaths as well.
The two nations now most responsible for the problem have comparatively little incentive to do anything about it.