U.S. energy-related carbon dioxide (CO2) emissions in 2016 totaled 5,170 million metric tons (MMmt), 1.7% below their 2015 levels, after dropping 2.7% between 2014 and 2015. These recent decreases are consistent with a decade-long trend, with energy-related CO2 emissions 14% below the 2005 level in 2016.
As noted in a recent article on energy use, both oil and natural gas consumption were higher in 2016 than in 2015, while coal consumption was significantly lower. Consistent with changes in fuel consumption, energy-related CO2 emissions in 2016 from petroleum and natural gas increased 1.1% and 0.9%, respectively, while coal-related emissions decreased 8.6%.
There are several ways to assess CO2 emissions trends within the context of measures of economic activity. Carbon intensity is a measure that relates CO2 emissions to economic output. Early estimates indicate that gross domestic product (GDP) grew at a rate of 1.6% in 2016, down from 2.6% in 2015. Taken together with a 1.7% decline in energy-related CO2, the 1.6% estimate of economic growth implies a 3.3% decline in the carbon intensity of the U.S. economy. In 2015, carbon intensity of the economy had decreased by 5.3%.
The U.S. transportation sector was the only consumption sector where CO2 emissions increased in 2016. CO2 emissions from the transportation sector increased by 1.9%, largely reflecting emissions from motor gasoline, which increased 1.8% in 2016. Emissions from the transportation sector surpassed those from the power sector during 2016—a trend that persists through at least 2040 in the Reference case projections in EIA’s 2017 Annual Energy Outlook.
CO2 emissions from the electric power sector fell by 4.9% in 2016. A significant reduction in coal use for electricity generation was offset by increased generation from natural gas and renewable sources. Renewables do not emit CO2, and a shift towards natural gas from coal lowers CO2 because natural gas has lower emissions per unit of energy than coal and because natural gas generators typically use less energy than coal plants to generate each kilowatthour of electricity. Overall, the data indicate about a 5% decline in the carbon intensity of the power sector, a rate that was also realized in 2015. Since 1973, no two consecutive years have seen a decline of this magnitude, and only one other year (2009) has seen a similar decline.
Weather also affected the level of energy use and CO2 emissions in 2016. Because more energy is used for heating than for cooling, warm years can translate to less energy consumption if increased cooling needs during warm summers are less than the reduced heating needs during warm winters. Based on preliminary data, 2016 is expected to have had 10% fewer heating degree days (indicating lower heating demand) and 13% more cooling degree days (indicating more cooling demand) than normal. Heating degree days in 2016 were the second fewest of any year since at least 1949, consistent with relatively warmer winter months.