The paper surveys the major challenges to stabilizing the atmospheric CO2 concentration. Climate change, and policies to deal with it, is viewed as an energy problem. The energy problem stems from the fact that no combination of carbon-free energies is currently capable of displacing fossil fuels as the main sources of the world's base load energy requirements. The paper provides rough estimates of the amount of carbon-free energy required to stabilize climate, the potential contribution of "conventional" carbon-free energies, the contribution of renewable energies, and the size of an "advanced energy technology gap". The findings indicate that stabilizing CO2 concentration will require a long-term commitment to research, develop, and eventually deploy new energy sources and technologies including hydrogen. The paper suggests that the role of technology is what makes stabilizing CO2 concentration economically feasible. In this respect energy technology and economics are complementary, with advances in the former requiring something more than a reliance on market-based instruments, such as carbon taxes and emission permits. The analysis has implications for the credibility of commitments to target climate change-related factors such as CO2 emissions. (c) 2006 Elsevier Ltd. All rights reserved.