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.

Among the most widely cited emissions projections are those developed by the Energy Information Administration (EIA) of the U.S. Department of Energy. Under EIA’s mid-range or “reference case” scenario, global emissions of CO2 from the consumption of fossil fuels are projected to rise 30 percent over the period from 2006-2025.