Carbon emissions have been trending downward, but not quickly enough to offset fluctuations in weather patterns.
A colder winter was one of the main reasons carbon dioxide emissions from energy use rose in the United States by 2.5 percent in 2013, according to new data from the Energy Information Agency. Besides a small rise in the price of natural gas and slightly cheaper coal, the weather played the biggest role in in pushing up emissions, the IEA says.
