The United States saw a drop in overall greenhouse gas emissions of 2.9 percent from 2007 to 2008, according to the 2010 U.S. Greenhouse Gas Inventory Report released on Thursday.
The U.S. Environmental Protection Agency reported that total emissions of the six main greenhouse gases including carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride were equivalent to 6,957 million metric tons of carbon dioxide in 2008.
EPA says the downward trend is attributed to a decrease in carbon dioxide emissions associated with fuel and electricity consumption. The inventory also calculates carbon dioxide emissions removed from the atmosphere by carbon sinks, a process which occurs through the uptake of carbon by forests, vegetation and soils.
Fossil fuel combustion is the largest source of carbon dioxide in the U.S. and accounted for approximately 79 percent of global warming potential weighted emissions since 1990.
Despite the 2008 decline, emissions were still 13.5 percent higher than they were in 1990. And on the same date the 2010 U.S. Greenhouse Gas Inventory was released, NASA reported that March 2010 was the warmest on record.