According to the US Energy Information Administration (EIA), energy-related CO2 emissions in the United States reached their lowest level since 1991 in the first half of 2016, to 2.53 Gt, thanks to mild weather and structural fuel changes in the US power mix.
In the first six months of 2016, the US had the fewest heating degree days (an indicator of heating demand) since at least 1949. Warmer weather reduced primary energy consumption (-2% in the first half of 2016 compared with the same period of 2015), especially in the residential sector (-9%) and in the power sector (-3%).
In addition, the structural shift of the US power mix to gas and renewables contributed to reducing CO2 emissions: coal consumption fell by 18% over the first half of 2016, while gas consumption dipped by 1%, more than offsetting the 1% increase in oil consumption. Moreover, the consumption of renewable fuels rose by 9% over this period: wind power accounted for half of the increase, followed by hydropower (easing of drought conditions on the West Coast) with 35% and solar with 13%.