"On June 25, 2013, President Obama affirmed his commitment to reduce U.S. greenhouse gas (GHG) emissions by 17% below 2005 levels by 2020 if all other major economies agreed to limit their emissions as well. In addition, during a November 2014 trip to China, President Obama announced a new policy target to reduce U.S. net GHG emissions by 26%-28% by 2025. Whether these objectives will be met is uncertain, but emission levels and recent trends remain a topic of interest among policy makers. […]This first section of this report provides current levels and recent trends in U.S. GHG emissions. The second section takes a closer look at some of the key factors that influence emission levels. The third section discusses the challenges in making GHG emission projections by comparing observed emissions with preobserved emission estimates."
CRS Report for Congress, R43795
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html