As discussed in parts 1 though 3of this series, the global demand for energy, and fossil fuels are expected to increase. At the same time, the supplies to meet that demand are declining. We examined how the gap between supply and demand is at risk of becoming too large and making the current economic crisis far worse. Finally we examined how a comprehensive policy that includes increasing U.S. supply and decreasing U.S. demand for fossil fuels can help ensure that we have access to a cost-effective and reliable source of energy for the foreseeable future.