U.S. greenhouse gas emissions rose less than 1 percent in 2014, despite a surge in manufacturing, increased driving and use of more heating fuels from an unexpected cold snap, the Environmental Protection Agency said Monday.

The country's emissions rose from 6.81 billion metric tons in 2013 to 6.87 billion metric tons of carbon dioxide in 2014. That's still below their level in 1996, the year that marked the beginning of an emission surge that ended during the recession. The decade-long surge between 1997 and 2007 saw carbon emissions steadily creep above 7 billion metric tons to more than 7.4 billion metric tons, the EPA said in its latest draft emission inventory report.

"Total U.S. emissions have increased by 7.7 percent from 1990 to 2014, and emissions increased from 2013 to 2014 by 0.9 percent," the draft report says.

It notes factors, such as the year's "relatively cool winter conditions" — the polar vortex – that led homeowners and businesses to use more heating fuel, which led to an emission increase compared to the previous year's 6.811 billion metric tons.

"In 2014 there also was an increase in industrial production across multiple sectors resulting in slight increases in industrial sector emissions," the EPA says. "Lastly, transportation emissions increased as a result of a small increase in vehicle miles traveled and fuel use across on-road transportation modes."

Since 1990, U.S. emissions have increased at an average annual rate of 0.3 percent.

The report is being done as part of its requirements under the 1992 United Nations climate change convention. The report is due to the U.N. in April, the same month countries are to assemble at U.N. headquarters in New York to sign the Paris climate change accord that was agreed to in December. Many scientists blame greenhouse gases such as carbon dioxide for driving manmade climate change.