tis and asthma), constituted the vast majority of monetized damages, with premature mortality being the single largest health-damage category.

Some external effects could only be discussed in qualitative terms in this report. Although we were able to quantify and then monetize a wide range of burdens and damages, many other external effects could not ultimately be monetized because of insufficient data or other reasons. In particular, the committee did not monetize impacts of criteria air pollutants on ecosystem services or nongrain agricultural crops, or effects attributable to emissions of hazardous air pollutants.2 In any case, it is important to keep in mind that the individual estimates presented in this report, even when quantifiable, can have large uncertainties.

In addition to its external effects in the present, the use of fossil fuels for energy creates external effects in the future through its emissions of atmospheric greenhouse gases (GHGs)3 that cause climate change, subsequently resulting in damages to ecosystems and society. This report estimates GHG emissions from a variety of energy uses, and then, based on previous studies, provides ranges of potential damages. The committee determined that attempting to estimate a single value for climate-change damages would have been inconsistent with the dynamic and unfolding insights into climate change itself and with the extremely large uncertainties associated with effects and range of damages. Because of these uncertainties and the long time frame for climate change, our report discusses climate-change damages separately from damages not related to climate change.



Although the committee considered electricity produced from coal, natural gas, nuclear power, wind, solar energy, and biomass, it focused mainly on coal and natural gas—which together account for nearly 70% of the nation’s electricity—and on monetizing effects related to the air pollution from these sources. From previous studies, it appeared that the electricity-generation activities accounted for the majority of such external effects, with other activities in the electricity cycle, such as mining and drilling, playing a lesser role.


Hazardous air pollutants, also known as toxic air pollutants, are those pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects and birth defects, or adverse environmental effects.


Greenhouse gases absorb heat from the earth’s surface and lower atmosphere, resulting in much of the energy being radiated back toward the surface rather than into space. These gases include water vapor, CO2, ozone, methane, and nitrous oxide.

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