US energy-related CO2 emissions are expected to be 2% higher in 2013 than in 2012, according to a new report by the US Energy Information Administration (EIA).
This is the first time since 2010 that emissions increased compared with the preceding year.
The EIA contributes the rise to a small increase in coal consumption in the electric power sector.
"The impact on overall emissions trends remains fairly small," the EIA wrote.
Compared with 2005 levels, 2013 emissions have decreased by about 10% – "a significant contribution towards the goal of a 17% reduction in emissions from the 2005 level by 2020 that was adopted by the current Administration," the EIA writes.
The Agency also shows that CO2 emissions from coal and petroleum products have been declining since 2005, while natural gas' contribution to emissions has risen by nearly 20%.
Energy-generation – which includes the burning of coal, natural gas and oil for electricity and heat – is the largest single source of global greenhouse gas emissions, according to the US Environmental Protection Agency (EPA).
The US was responsible for about 19% of the world's CO2 emissions from fossil fuel combustion and some industrial processes in 2008, EPA data shows.
China accounted for about one-quarter of this figure, while European Union countries represented 13%.