Carbon dioxide accounted for 80 percent of the United States' greenhouse gas emissions in 2014, with the burning of fossil fuels accounting for most of those emissions, according to an Environmental Protection Agency report.
According to the EPA's final Greenhouse Gas Inventory, carbon dioxide was the top source of greenhouse gas emissions, followed by methane and nitrogen oxide.
Of the 5,556 metric tons of carbon dioxide emitted in 2014, 5,208.2 metric tons, or 94 percent, came from the burning of fossil fuels, according to the report. That makes the burning of fossil fuels easily the top source of greenhouse gas emissions in the U.S. Many scientists blame greenhouse gases such as carbon dioxide for driving manmade climate change.
Power plants and transportation were the two biggest sectors for greenhouse gas emissions, according to the report.
Greenhouse gas emissions grew in 2014, up 0.70 metric tons from 2013. It's the second straight year greenhouse gas emissions have grown after years of decreasing emissions brought on by the 2008 recession.
Overall, greenhouse gas emissions have increased by 7.4 percent since 1990, the first year the report was done. Since 1990, greenhouse gas emissions have increased at a rate of 0.3 percent per year, the report stated.
The report is done as part of the nation's requirements under the 1992 United Nations climate change convention. The report is due to the U.N. this month, and countries will assemble at U.N. headquarters in New York next week to sign the Paris climate change accord that was agreed to in December.