Energy-related carbon dioxide pollution grew by 2 per cent last year after declining several years in a row, a government report said.
The increase was largely due to a small boost in coal consumption by the electric power industry, according to the study by the US Energy Information Administration.
American cars and factories spewed 5.38 billion tons of carbon dioxide in 2013, up from 5.27 billion in 2012, the report said. Carbon dioxide is the chief man-made global warming gas.
Coal, long the dominant source for US electricity, has regained some market share in recent months as natural gas prices have increased following historic lows in 2012.
Coal generated about 39 per cent of the nation's electricity in October, compared with 28 per cent for natural gas, the EIA said. Coal supplied about 37 per cent of US electricity in 2012, with natural gas at 30 per cent.
Even with the uptick, overall US carbon emissions remained 10 per cent below 2005 levels, more than half the reduction needed to achieve President Barack Obama's goal of reducing carbon emissions by 17 per cent from 2005 levels by 2020.
Obama has launched a major second-term drive to combat climate change, bypassing Congress as he imposes first-ever limits on carbon pollution from new and existing power plants.
Forty per cent of US carbon emissions, and one-third of greenhouse gases overall, come from electric power plants, according to the EIA.
Under Obama's plan, the Environmental Protection Agency will propose guidance for states to regulate greenhouse gas emissions from future power plants, as well as those already in existence, to reshape where Americans get electricity. The plan is intended to help move the United States from a coal-dependent past into a future fired by cleaner sources of energy such as wind and solar power, nuclear energy and natural gas.
The EPA says the plan would not raise the price of electricity or cause major disruptions to the US economy, a claim the coal industry and its allies in Congress dispute.
Obama's plan also would boost renewable energy production on federal lands, increase efficiency standards and prepare communities to deal with higher temperatures that many scientists say are being caused by human activity. The 12 hottest years on record all have occurred in the past 15 years.
