That is, the global economy increases more than 7-fold and population nearly doubles. The only major difference between the scenarios is the energy technology portfolio that underlies the scenarios. Figure 1 . The upper curve assumes that the world meets increased energy demand over the coming century with existing technology. After accounting for these dramatic improvements in energy efficiency, overall energy demand still increases globally by a factor of 5 and in the US by a factor of 2.
Fossil fuels remain the dominant fuel.
The third and bottom curve on this figure represents an economically efficient pathway that ultimately stabilizes atmospheric concentrations of carbon. We choose the goal of stabilizing concentrations because that is the goal that is set forth in the United Nations Framework Convention on Climate Change, a treaty which the U.S. Senate and 183 other nations have ratified and is now in force as international law. Advanced carbon capture and sequestration technologies enable significant amounts of fossil-based fuels to maintain a large market share. Nuclear technologies penetrate the market heavily internationally, but unless it regains its public acceptance, it does not penetrate the U.S. market. This growth will require extraordinary amounts of energy.