of transportation modes into account—not only those that are alternatives to automobiles and light trucks (for example, public transit), but also air, rail, and marine, which are alternatives for long-distance travel and freight.
Assessment of energy use and its impacts in the industrial sector in particular (but in all sectors to some extent) could be improved by development of more extensive databases that contain details about specific forms of energy use and associated waste streams. Such databases should be designed so that life-cycle analysis of alternatives can be made without inadvertent double counting.
A more quantitative assessment of industrial sector externalities, done collaboratively between the government and industry, would be valuable in informing priorities for future initiatives to reduce the externalities associated with industrial operations. Such an assessment was not possible in this study largely because of data limitations.
More research on climate damages is needed to estimate the impacts of climate change, especially impacts that can be expressed in economic terms, as current valuation literature relies heavily on climate-change impact data from the year 2000 and earlier.
Marginal damages of GHG emissions may be highly sensitive to the possibility of catastrophic events. More research is needed on their impacts, the magnitude of the damages in economic terms, and the probabilities associated with various types of catastrophic events and impacts.
Estimates of the marginal damage of a ton of CO2-eq include aggregate damages across countries according to GDP, thereby giving less weight to the damages borne by low-income countries. This aggregate estimate should be supplemented by distributional measures that describe how the burden of climate change varies among countries.
In aggregate, the damage estimates presented in this report for various external effects are substantial. Just the damages from external effects that the committee was able to quantify add up to more than $120 billion for