If Congress establishes a federal program to manage or reduce GHG emissions, the emission requirements would likely impact different states differently. However, predicting the different impacts of policies is a complicated task, because multiple factors play a role. Such factors include alternative design elements of a GHG emissions reduction program, the availability and relative cost of mitigation options, and the regulated entities' abilities to pass compliance costs on to consumers. In this report, GHG emissions intensity is a measure of GHG emissions from state sources divided by the state's overall economic output, or gross state product. An analysis of these factors and how they compare among the states may contribute to a more informed debate regarding potential policy approaches. Annual growth rates for GHG emissions and the emission drivers vary significantly among the U.S. states. Greenhouse Gas Emissions Intensity

Of the three GHG emission drivers—population, per capita income, and GHG emissions intensity—the most relevant in terms of climate change policy is GHG intensity. In fact, if the United States is to reduce its emissions, while maintaining population and per capita income growth rates, a stringent reduction in GHG emissions intensity would be required. The primary factors that determine CO 2 emissions intensity in a state are its energy intensity and the carbon content of its energy use (or fuel mix). Energy Intensity

Energy intensity is the amount of energy a state consumes—typically measured in tons of oil equivalent (toe)—per its level of economic output (gross state product). Economic Structure

A state's economic structure likely plays an important role. A measure that tracks personal transportation use in a state is vehicle miles traveled (VMT) per person. A state's per capita VMT is another factor that likely impacts a state's energy intensity. Electricity Exports/Imports

Another important factor that affects a state's carbon content of energy use is whether the state is a net importer or exporter of electricity. In the above carbon content of energy data ( Table 7 ), if one state uses an energy source (e.g., coal) to generate electricity and then sells the electricity to a consumer in a second state, the CO 2 emissions are attributed to the generating state, but the energy use is attributed to the consuming state. States with high energy intensity may have a high percentage of carbon-intensive industries (e.g., manufacturing). To stabilize national GHG emission growth, the entire United States would need to achieve annual reductions in GHG intensity of approximately 3% (assuming population and income continue to grow at a combined rate of 3%). Reducing GHG emissions in the United States would necessitate further declines in GHG intensity.
Instituting policies to manage or reduce greenhouse gas (GHG) emissions would likely impact different states differently. Understanding these differences may provide for a more informed debate regarding potential policy approaches. However, multiple factors play a role in determining impacts, including alternative design elements of a GHG emissions reduction program, the availability and relative cost of mitigation options, and the regulated entities' abilities to pass compliance costs on to consumers.
Three primary variables drive a state's human-related GHG emission levels: population, per capita income, and the GHG emissions intensity. GHG emissions intensity is a performance measure. In this report, GHG intensity is a measure of GHG emissions from sources within a state compared with a state's economic output (gross state product, GSP). The GHG emissions intensity driver stands apart as the main target for climate change mitigation policy, because public policy generally considers population and income growth to be socially positive.
The intensity of carbon dioxide (CO2) emissions largely determines overall GHG intensity, because CO2 emissions account for 85% of the GHG emissions in the United States. As 98% of U.S. CO2 emissions are energy-related, the primary factors that shape CO2 emissions intensity are a state's energy intensity and the carbon content of its energy use.
Energy intensity measures the amount of energy a state uses to generate its overall economic output (measured by its GSP). Several underlying factors may impact a state's energy intensity: a state's economic structure, personal transportation use in a state (measured in vehicle miles traveled per person), and public policies regarding energy efficiency.
The carbon content of energy use in a state is determined by a state's portfolio of energy sources. States that utilize a high percentage of coal, for example, will have a relatively high carbon content of energy use, compared to states with a lower dependence on coal. An additional factor is whether a state is a net exporter or importer of electricity, because CO2 emissions are attributed to electricity-producing states, but the electricity is used (and counted) in the consuming state.
Between 1990 and 2000, the United States reduced its GHG intensity by 1.6% annually. Assuming that population and per capita income continue to grow as expected, the United States would need to reduce its GHG intensity at the rate of 3% per year in order to halt the annual growth in GHG emissions. Therefore, achieving reductions (or negative growth) in GHG emissions would necessitate further declines in GHG intensity.