Greenhouse gas emissions have increased markedly since the pre-industrial era and are increasing at such a rate that their concentration in the atmosphere is producing a warming influence on the global climate. In order to make well-informed decisions on ways to reduce greenhouse gas emissions, it is important to understand how the different economic sectors contribute to the production of greenhouse gases, which sectors are relatively carbon dioxide (CO2) intensive, and how these patterns have evolved over time.
To that end, this report analyzes energy-related CO2 emissions and intensities for 349 industries, Government (Federal, state and local), and Households for the 1998 to 2006 period. The 349 industries cover the entire economy, providing information on detailed subsectors within the aggregate sectors of Agriculture, Forestry and Fisheries, Mining, Construction, Manufacturing, Transportation Services, and All Other Services. CO2 intensities for industries and Government refer to the emissions produced per billion dollars of output. CO2 intensities for Households are measured by emissions per thousand households.
The primary findings of the report are as follows:
- A large number of industries in the U.S. have seen declines in emissions intensity (that is, gains in emissions efficiency) over the past decade. These improvements at the industry level have contributed significantly to the overall pattern of greater emissions efficiency in the economy.
- Energy-related CO2 emissions in the U.S. increased more slowly than overall output growth during 1997 to 2007, indicating that the CO2 intensity of the economy declined.
- If not for these improvements in emissions efficiency, we estimate that CO2 emissions in the U.S. would have been about 25 percent higher than actual emissions in 2007.
- The Manufacturing sector is often the focus of discussion about pollution control.
- Manufacturing was responsible for about one-quarter of total CO2 emissions in 2006, down from 30 percent in 1998. It reduced its CO2 intensity over the 1998 to 2006 period.
- The level of CO2 output as well as the gain in efficiency varies significantly within the Manufacturing sector. For example, between 1998 and 2006, Chemicals had a significant emissions efficiency gain, while Nonmetallic Mineral Products had an efficiency loss.
- The Transportation Services sector, which accounts for about 15 percent of total emissions in the U.S., increased its emissions and showed only slight gains in emissions efficiency.