The world at night.

But that condition has come at a cost—to irreplaceable resources, to the environment, and to our national independence. Society has begun to question the methods we use to power modern life and to search for better alternatives. As the nationwide debate continues, it is already evident that managing energy use wisely in the 21st century will call for balancing three essential, but quite different, concerns: resources, responsibility, and security.

Our appetite for energy appears boundless, but traditional supplies are not. We are depleting the planet’s finite stores of fossil fuels millions of times faster than they are formed, a situation that cannot continue indefinitely. Eventually we must devise ways to keep resources and consumption in sustainable equilibrium. Addressing the issue of sustainable resources in a nation that gets 85% of its total energy from oil, coal, and gas is a formidable goal, but one that we must pursue rigorously.

The combustion of fossil fuels releases carbon dioxide (a major “greenhouse” gas) into the atmosphere, and most climate scientists believe that the buildup of those gases is the primary cause of global warming in recent decades.