U.S. Government commitment to the UNFCCC to communicate U.S. actions and policies addressing climate change transparently. The agency must receive comments on or before noon, October 24, 2013.
A major contributor to the decline in U.S. GHG emissions has been the displacement of coal with natural gas that is extracted from shale rock formations through hydraulic fracturing and horizontal drilling. The production of "shale gas" has grown rapidly in recent years. In 1996, U.S. shale gas wells produced 0.3 trillion cubic feet (8.5 billion cubic meters) of natural gas, representing 1.6 percent of U.S. gas production. By 2011, production of shale gas had increased to 8.5 trillion cubic feet (241 billion cubic meters) of natural gas, 30 percent of U.S. gas production. The extraction and use of shale gas are projected to continue to grow during the next several years.The U.S. transportation system has evolved to meet the needs of a highly mobile, dispersed population and a large economy. Automobiles and light trucks still dominate the passenger transportation system, and the highway share of passenger miles traveled. In 2013, the most recent year of available data, automobiles and light trucks constituted about 87 percent of the passenger miles traveled, down 2 percentage points from the highway share listed in the 2010 CAR. Air travel accounted for slightly more than 11 percent (up 1.5 percentage points from the 2010 CAR), and mass transit and rail travel combined accounted for only about 1 percent of passenger miles traveled. . .Given implementation of programs and measures in place as of September 2012 and current economic projections, total gross U.S. GHG emissions are projected to be 4.6 percent lower than 2005 levels in 2020. Between 2005 and 2011 total gross U.S. GHG emissions have declined significantly due a combination of factors, including the economic downturn and fuel switching from coal to natural gas (U.S. EPA 2013). Emissions are projected to rise gradually between 2011 and 2020. Emissions are projected to remain below the 2005 level through 2030, despite significant increases in population (26 percent) and GDP (69 percent) during that time period. More rapid improvements in technologies that emit fewer GHGs, new GHG mitigation requirements, or more rapid adoption of voluntary GHG emission reduction programs could result in lower gross GHG emission levels than in the "with measures" projection.
Between 2005 and 2020, CO2 emissions in the "with measures" projection (measures in place as of 2012) are estimated to decline by 7.5 percent. In contrast, in the 2010 CAR, CO2 emissions were expected to increase by 1.5 percent between 2005 and 2020 (U.S. DOS 2010), a change of about 9 percent, and in the 2006 CAR, emissions were expected to increase by 14 percent between 2004 and 2020 (U.S. DOS 2006). During the same period, CH4 and N2O emissions are expected to grow by 3.5 percent and 6.1 percent, respectively. The most rapid growth is expected in fluorinated GHGs (HFCs, PFCs, and SF6) which are expected to increase by more than 60 percent between 2005 and 2020, driven by increasing use of HFCs as 6 substitutes for ODS.