Power plants were the largest source of greenhouse gas (GHG) emissions in the US in 2014.

They accounted for 30% of total pollution in the country, new data from the Environmental Protection Agency (EPA) revealed.

It added the nation emitted more than 6,000 million metric tons of CO2 in the same period.

The transportation sector was the second largest source, accounting for 26% followed by industry and manufacturing with 21% of the total.

The data, which presents a national level overview of annual greenhouse gas emissions since 1990, also shows a 9% drop in emissions since 2005 and a 1% increase in 2014 from 2013 levels.

It stated: “Greenhouse gases are the primary driver of climate change. We are already seeing impacts of climate change in the US, including warming temperatures, changes in precipitation, increases in the frequency or intensity of some extreme weather events and rising sea levels. These impacts threaten Americans’ health by affecting food safety as well as water and air quality.”

Earlier this year the US Supreme Court decided to block President Barack Obama’s Clean Power Plan to cut emissions from power plants by 32%.