Total U.S. greenhouse emissions were 6,673 million metric tons of carbon dioxide equivalent in 2013. By sector, power plants were the largest source of emissions, accounting for 31 percent of total U.S. greenhouse gas pollution.

The transportation sector was the second largest source, at 27 percent. Industry and manufacturing were the third largest source, at 21 percent. The increase in total national greenhouse gas emissions between 2012 and 2013 was due to increased energy consumption across all sectors in the U.S. economy and greater use of coal for electricity generation.

This year, the EPA is publishing key data in a new, online Greenhouse Gas Inventory Data Explorer tool, which allows users to view, graph and download data by sector, year and greenhouse gas. The EPA will be holding an informational webinar on April 22 at 1 p.m. EST to demonstrate the Data Explorer tool and its features, and provide a tutorial on common searches.

The EPA said in a prepared statement that greenhouse gas emissions are driving climate change, which threatens the health and well-being of Americans and future generations through decreased air quality; extremes in heat and other weather events; increased incidence of food-, water-, and insect-borne diseases; and other impacts. And added that “comprehensive greenhouse gas emissions data are an essential tool to help understand the primary sources of emissions and identify cost-effective opportunities to reduce them.”

According to the EPA, it is working to address carbon pollution from the power and transportation sectors, and to improve energy efficiency in homes, businesses and factories. Current greenhouse gas and fuel economy standards for cars and light trucks and EPA’s proposed Clean Power Plan claims it will eliminate billions of tons of greenhouse gas pollution, save lives through air quality benefits and save Americans money at the pump.

The agency prepares the inventory annually in collaboration with other federal agencies and submits the report to the Secretariat of the United National Framework Convention on Climate Change every year on April 15.

The inventory presents historical emissions since 1990 and covers seven key greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride. In addition to tracking U.S. greenhouse gas emissions, the inventory also calculates carbon dioxide that is removed from the atmosphere through the uptake of carbon in forests and other vegetation. The EPA has been publishing the inventory since 1994, but tracks back to 1990.