A mild winter, followed by a cool summer caused U.S. carbon dioxide emissions to decline last year, according to the Energy Department. The results were hailed by the White House as support for its global warming policies.
The department's Energy Information Administration said Wednesday that preliminary data shows a 1.3 percent decline in the amount of heat-trapping carbon dioxide released in 2006 from energy-related sources, the first decline in 11 years and the biggest decline since 1990.
The White House quickly issued a statement from President Bush hailing the drop in the principal "greenhouse gas" that scientists have linked to a warming of the earth.
"We are effectively confronting the important challenge of global climate change through regulations, public-private partnerships, incentives and strong economic investments," Bush said in the statement.
The agency, which tracks energy and related statistics, said that its "flash estimate" for 2006 shows power plants, industry, homes, businesses and motor vehicles produced 5,877 million metric tons of carbon dioxide in 2006 compared to 5,955 million metric tons in 2005.
Whether the decline of 78 million metric tons was an anomaly, or an indicator of something more, was unclear.
The Energy Department report said one reason for the decline was that 2006 had "weather conditions favorable for emission reductions."
Carbon dioxide is produced from burning fossil fuels including natural gas and coal which are used widely to produce electricity to heat homes in winter and run air conditioners for cooling in summer.
In 2006 there was a mild winter that reduced heating degree days by 7.4 percent, and a cooler than normal summer that cut cooling-degree days by 1 percent, both compared to 2005, the agency said.
Carbon dioxide from natural gas declined by 1.7 percent and coal — which accounts for the most carbon emissions per unit of energy produced of any fossil fuel — was down 0.9 percent. Emissions from burning gasoline and diesel increased, but those increases were offset by declines in other petroleum fuels such as heating oil, said the agency.
The reductions resulted in the largest decline in carbon intensity — the amount of emissions related to economic growth — since 1990 with a reduction of 4.5 percent, said the report.
Bush has opposed mandatory reductions in carbon dioxide emissions, even as the Democratic-controlled Congress is considering legislation that would require caps on carbon with a goal of cutting these releases by as much as 80 percent by mid-century. Many scientists say that's what's needed to reverse the trend toward severe global warming.
The president has focused on reducing carbon intensity — but not actual emissions — by 18 percent within five years. He said Wednesday the 2006 numbers "are putting us well ahead of what is needed annually to meet my greenhouse gas intensity reduction goal."