Where Greenhouse Gases Come From 80 percent 26 percent of the U.S.’s carbon dioxide emissions in 2016 burning fossil fuels more than two-thirds Where Greenhouse Gases Come From Where Greenhouse Gases Come From more than two-thirds Where Greenhouse Gases Come From Where Greenhouse Gases Come From burning fossil fuels burning fossil fuels Where Greenhouse Gases Come From 35% of the U.S.’ greenhouse gas emissions