U.S. Greenhouse Gas Emissions Plunge in 2008 - Record Gas Prices, Economy Major Drivers

Driven by record-high gas prices in the first half of the year and the economic crisis that hit in the later half of the year, United States greenhouse gas emissions plunged by the largest amount in decades, according to preliminary data released today by the U.S. Energy Information Administration.

U.S. greenhouse gas emissions, which drive global climate change, fell to 2.8% in 2008 to 5.8 billion metric tons of carbon dioxide equivalent (CO2-e), the lowest level of emissions in any year since 2000. Total U.S. energy consumption also fell 2.2% in 2008, the EIA reports.

(Sorry for poor image quality, blame the source: the EIA)

The drop in oil consumption in 2008 was the major driver of lower greenhouse gas emissions, as oil topped record prices throughout most of the year. Emissions from petroleum fell 6% in 2008, down 155 million metric tons CO2-e in 2008. Natural gas emissions rose slightly, inching up 1%, or 13 million metric tons CO2-e. Emissions from the combustion of coal fell 1.1%, by 23 million metric tons CO2-e.

Electricity generation was down 1% in 2008, leading the the drop in coal combustion, and a decline in electricity-sector emissions of 50 million metric tons CO2-e, a 2.1% drop. Electricity generation from non-carbon emitting sources (wind, solar, hydro, nuclear, etc.) increased by 18.6 billion kilowatt-hours (1.7 percent) in 2008, even as electricity generation overall fell, bringing the non-carbon share of generation up from 27.8% in 2007 to 28.5% in 2008.

In 2008, transportation CO2 emissions fell 5.2%, the largest annual decline since 1990. In contrast, transportation emissions have risen by 1.1% annually since 1990, as can be seen in the graphic to right.

Interestingly, emissions fell in 2008 despite an overall growth in economic output (GDP). While GDP plunged at an annual rate of 6.3% in the 4th quarter of 2008, as the economic crisis accelerated, GDP was up by 1.1% overall in 2008.

Emissions fell despite this economic growth due to an overall "decarbonization" of the economy, a fall in energy intensity and emissions intensity of the economy which has held strong for the past decades (see graphic to right). The EIA reports that energy-related CO2 emissions per unit of GDP dropped 3.8 percent in 2008, enough to outpace the modest economic growth in the year. The emissions intensity of the economy is the product of two factors, energy intensity of the economy (energy/GDP), which includes energy efficiency and productivity factors, and CO2 intensity of the energy supply (CO2/energy), which factors in the mix of energy sources and fuels used. According to the EIA, both factors fell in 2008, with energy per GDP falling 3.3% and CO2 intensity of the energy supply inching down 0.6%.

For more, check out the preliminary report from the Energy Information Administration here. The full report will be released in "the fall of 2009."