Still, U.S. greenhouse gas emissions in 2001 were 11.9 percent higher than in 1990, the EIA said.

The Energy Department's analytical arm said U.S. greenhouse gas emissions last year, including carbon dioxide, methane and nitrous oxide, totaled 1,883 million metric tons, down from 1,907 million metric tons the year before.

The EIA said the decline in emissions could be attributed to several factors:

- A reduction in U.S. economic growth from 3.8 percent in 2000 to 0.3 percent in 2001.

- A 4.4 percent drop in manufacturing output that lowered industrial emissions.

- Warmer winter weather that decreased the demand for heating fuels.

- A drop in electricity demand and coal-fired power generation that reduced emissions from electricity generation.

Emissions of carbon dioxide, which account for 84 percent of total U.S. greenhouse gas emissions, decreased by 1.1 percent in 2001 to 1,579 million metric tons, the EIA said.

President George W. Bush withdrew the United States last year from the international Kyoto treaty that seeks to reduce greenhouse gas emissions among industrialized countries, fearing that the treaty's requirements would hurt the U.S. economy.

Instead, the Bush administration said it wants to conduct years of further research on the causes of global warming and in the meantime will promote voluntary efforts among U.S. industries to reduce their greenhouse gas emissions.

The European Union and Japan, which have adopted the Kyoto treaty, have criticized the Bush administration for not doing more to cut U.S. emissions. The United States is the world's biggest energy consumer and also its largest emissions producer.

There is increasing interest in promoting U.S. forests and agricultural lands as absorbers of carbon emissions.

The EIA said U.S. forests absorb about 246 million metric tons of carbon annually, equal to 15.6 percent of U.S. carbon dioxide emissions.

There has been a reversal of the extensive deforestation of the United States that occurred in the late 19th and early 20 centuries. Since then, millions of acres of formerly cultivated land have been abandoned and returned to forest, absorbing carbon on a large scale, the EIA said.