In this paper I discuss general conceptual issues in the estimation of the impacts of CO2 emissions from soils and biomass, over time, as a result of land-use change (LUC) due to increased demand for energy crops. The effect of LUC on climate depends generally on the magnitude and timing of changes in soil and plant carbon, and in particular on the timing and extent of the reversion of land to original ecosystems at the end of the bioenergy program. Depending on whether one counts the climate impacts of any reversion of land uses, and how one values future climate-change impacts relative to present impacts, one can estimate anywhere from zero to very large climate impacts due to land-use change (LUC). I argue that the best method is to estimate the netpresent-value (NPV) of the impacts of climate change due to LUC. With this approach, one counts the reversion impacts at the end of the program and applies a continuous discounting function to future impacts to express them in present terms. In this case, the impacts of CO2 emissions from the initial LUC then are at least partially offset by the impacts of CO2 sequestration from reversion.

In this paper I discuss general conceptual issues in the estimation of the impacts of CO2 emissions from soils and biomass, over time, as a result of land-use change (LUC) due to increased demand for energy crops. The effect of LUC on climate depends generally on the magnitude and timing of changes in soil and plant carbon, and in particular on the timing and extent of the reversion of land to original ecosystems at the end of the bioenergy program. Depending on whether one counts the climate impacts of any reversion of land uses, and how one values future climate-change impacts relative to present impacts, one can estimate anywhere from zero to very large climate impacts due to land-use change (LUC). I argue that the best method is to estimate the netpresent-value (NPV) of the impacts of climate change due to LUC. With this approach, one counts the reversion impacts at the end of the program and applies a continuous discounting function to future impacts to express them in present terms. In this case, the impacts of CO2 emissions from the initial LUC then are at least partially offset by the impacts of CO2 sequestration from reversion.

Human activities associated with the production and use of energy and materials can pollute the air and water. Since the late 1960s concern about regional and local air pollution has led to the adoption of environmental laws and regulations regarding major polluting human activities, such as fuel use for transportation or electricity production. More recently, concern about the impact of human activities on global climate has led to discussions about ways to reduce emissions of the so-called "greenhouse gases" that affect global climate.

In the United States and worldwide, the transportation sector is one of the largest sources of urban air pollutants and greenhouse-gases (GHGs). As a result, policy makers and analysts often evaluate the impact of transportation policies on urban air quality and on global climate. The tools available for evaluating impacts on urban air quality (emission-factor models, travel models, and air-quality models) are reasonably well developed, but some of the tools for evaluating impacts on global climate (namely, lifecycle emissions models) are rudimentary and incomplete. This paper discusses some of the methodological and data issues pertinent to using lifecycle analysis (LCA) to evaluate the impacts of transportation on global climate.

Federal, state, and local governments spend over a hundred billion dollars per year to build and maintain roads and provide a variety of services, such as highway patrol, for motor-vehicle users (see report #7 in the author's social-cost series). To pay for these infrastructure and service expenditures governments do not charge motor-vehicle users a single, explicit, comprehensive price for the use of roadways and motor-vehicle-related services, but rather collect revenue from a variety of taxes and fees ranging from road tolls to motor-fuel taxes to general-fund tax receipts. Some of these taxes and fees, such as road tolls, function like prices on the use of public motor-vehicle infrastructure and service (MVIS); some, like sales tax receipts, are purely general taxes unrelated to motor-vehicle use; and some, like fuel-excise taxes, may be said to be "in-between" a price on the use of MVIS and a general tax on all commodities.

In our analysis of the social cost of motor-vehicle use, many of our data sources, methods, and estimates of cost apply in the first instance to all classes of motor vehicles. For example, we are given, or can estimate from primary data, the following:

- total government expenditures on the highways

- the air-pollution damage cost of emissions from gasoline service stations

- the air-pollution damage cost of emissions of PM10 from re-entrained road dust

- highway-patrol expenditures

- the cost of garages and parking spaces

- the cost of oil spills, per barrel of oil

All of these costs pertain to all motor vehicles: all autos, trucks, and buses. Although it can be interesting to estimate the cost of all motor-vehicle use, it typically will be more useful to estimate the cost of different classes of vehicles or of different fuel types, because analysts, policy makers, and regulators typically are interested in specific classes of vehicles, and specific fuels, rather than all motor-vehicles as a group. (For example, pollution regulations are set for individual classes of vehicles, not for all motor vehicles as a class.) Thus, it is useful to carry the analysis of total social cost a step further, and take a cost that initially applies to all motor-vehicles and apportion it to specific vehicle and fuel classes. This report develops such “allocation factors,” which can be used to apportion or disaggregate a total cost to specific vehicle and fuel classes.

Urban regions worldwide are dominated by the need to provide for large numbers of high-speed, high-mass vehicles. Current strategies result in congestion, social fragmentation, and environmental degradation. An alternative urban design is presented that incorporates two separate road systems: one for light, low-speed vehicles and another for heavy, high-speed vehicles. This design enhances travel efficiency and sense of community, while minimizing energy use, water pollution, and nonrenewable resource consumption.