Projections of long-term GHG emissions growth depend heavily on assumptions about critical factors such as economic and population trends and the rate of technology development and diffusion. Projections at the national level can be highly uncertain, and the uncertainties are especially acute in developing country economies, which tend to be more volatile and vulnerable to external shocks. The range in projections reflects both differing assumptions, for instance with respect to future policy choices, and substantial uncertainties, particularly regarding economic forecasts.

Since nearly three quarters of China’s GHG emissions result from the combustion of fossil fuels for energy, new Chinese energy policies will have a profound impact on China’s contribution to global warming. While China has traditionally avoided policies that explicitly target GHG emissions, its energy and forestry programs have provided the framework for its National Climate Change Program.

In the last few years, China has become the world’s leading source of greenhouse gases, especially carbon dioxide, and its emissions are growing rapidly. China now produces about one-fifth of annual global carbon dioxide emissions, just ahead of the United States. China’s per capita emissions, however, are just one-quarter of U.S. levels due to its relatively large population and high rate of poverty. In 2006, for instance, the average American produced approximately 20 metric tons of carbon dioxide; the average Chinese produced just 5 metric tons.

While China and the United States today emit approximately the same amount of greenhouse gases, it is worth noting that China’s per capita emissions are only one-fifth of those of the United States.