Fossil fuels are buried deposits of petroleum, coal, peat, natural gas, and other carbon-rich organic compounds derived from the dead bodies of plants and animals that lived many millions of years ago. Over long periods of time, pressure and heat generated by overlying sediments concentrate and modified these materials into valuable energy sources for human purposes. Fossil fuels currently provide about 90% of all commercial energy used in the world. They provide the power to move vehicles, heat living spaces, provide light, cook our food, transmit and process information, and carry out a wide variety of industrial processes. It is no exaggeration to say that modern industrial society is nearly completely dependent on (some would say addicted to) a continual supply of fossil fuels. How we will adapt as supplies become too limited, too remote, too expensive, or too environmentally destructive to continue to use is a...