U.S. carbon-dioxide pollution increased modestly last year after declining for several consecutive years, a new Energy Department report said on Monday. The 2 percent increase was largely due to a small rise in coal consumption in the electric power sector. According to a report from the Saudi Press Agency, SPA, coal, long the main source for U.S. electricity, has regained some market share in recent months as natural-gas prices have risen from historic lows in 2012. The department's Energy Information Administration, EIA, said U.S. cars and factories emitted 5.38 billion tons of carbon dioxide in 2013, up from 5.27 billion in 2012. Carbon dioxide is the primary man-made global-warming gas. Despite the 2013 increase, the EIA says overall U.S. carbon emission remained 10 percent below 2005 levels.