are intimately tied to, and immediately affect, the nation’s overall energy budget.

Our individual automotive and public-transit choices also have a substantial impact, because transportation takes up 28% of all U.S. energy consumption (and about 70% of all petroleum use). Even the 50% of total U.S. energy consumption that goes to commercial and industrial uses affects every single citizen personally through the cost of goods and services, the quality of manufactured products, the strength of the economy, and the availability of jobs.

The condition of the environment also holds consequences for all of us. Carbon dioxide (CO2) concentration in the atmosphere has risen about

Energy usage in the U.S. residential sector in 2006.

Energy usage in the U.S. residential sector in 2006.

CO2 emissions by U.S. economic sector and energy source in 2005.

CO2emissions by U.S. economic sector and energy source in 2005.

40% since the beginning of the industrial revolution—from 270 parts per million (ppm) to 380 ppm—and contributes to global warming and ensuing climate change. At present, the United States emits approximately one-fourth of the world’s greenhouse gases, and the nation’s CO2 emissions are projected to rise from about 5.9 billion metric tons in 2006 to 7.4 billion metric tons in 2030, assuming no changes to the control of carbon emissions. Of course this is not just a national concern. Worldwide, CO2 emissions are projected to increase substantially, primarily as a result of increased development in China and India. Future decisions about whether and how to limit greenhouse gas emissions will affect us all.

Before we can consider ways to improve our energy situation we must first understand the resources we currently depend on, as well as the pros and cons of using each one.

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