Washington: US energy-related carbon dioxide emissions fell a record seven percent in 2009, officials said late Wednesday, citing the economic slump and other factors including increased energy efficiency.
The drop of 405 million metric tonnes was the largest absolute and percentage decline since energy data collection began in 1949, the Energy Department said in a statement.
"Emissions developments in 2009 reflect a combination of factors, including some particular to the economic downturn, other special circumstances during the year, and other factors that may reflect persistent trends in our economy and our energy use," the agency`s Energy Information Administration said.
The decline is positive for efforts by the US and other countries to reduce emissions linked to global warming.
Officials said that even though some of the decline came from reduced economic activity, the country`s so-called energy intensity also fell.
Economic activity measured by gross domestic product fell 2.4 percent in 2009, but the population increased an estimated 0.9 percent.
Total energy consumption fell by 4.8 percent, with the industrial sector seeing the largest drop, of 9.9 percent.
The use of transportation fuel also fell, with higher prices in early 2009 causing people to drive less. Fuel efficiency of the US auto fleet also improved during the year.
Another factor was the conversion of some electric generation from coal, which produces more emissions, to natural gas.