Its CO2 emissions were in total 2,530 million metric tons, according to the US Energy Information Administration (EIA).
That was due to a decrease in coal and natural gas consumption with both registering a drop of 18% and 1% respectively compared to the same period in 2015.
On the other hand, consumption of renewables increased by 9% during the same period with wind accounting for nearly half of the increase.
Mild weather was another factor which supported the decrease of carbon emissions, as during the first six months of the year, the country had the fewest heating degree days since at least 1949, according to the EIA.
The report stated: “Warmer weather during winter months reduces demand for heating fuels such as natural gas, distillate heating oil and electricity. Overall, total primary energy consumption was 2% lower compared with the first six months of 2015.
“The decrease was most notable in the residential and electric power sectors, where primary energy consumption decreased 9% and 3%, respectively.”