CO2 Emissions from U.S. Cars Drop 12%

A 16% improvement in automobile efficiency and a 3.3% drop in vehicle miles traveled between 2007 and 2012 have contributed to a 12% decline in U.S. energy-related carbon dioxide emissions over the period, according to the U.S. Energy Information Administration.

The EIA reports that warmer weather and weaker industrial output also cut overall residential and industrial energy use. As a result, CO₂ emissions dropped last year to the lowest level since 1994. CO₂ emissions fell 3.8% in 2012 alone, despite a 2.8% increase in U.S. economic activity.

Lower residential energy use accounted for half the decline in energy use from 2011 to 2012. It was followed by transportation, which saw no increase in use for the second straight year. Energy consumption by the transportation sector accounted for 22% of the total decline year over year.

The net effect, the report notes, is that CO₂ emissions compared to gross domestic product declined by 6.5% in 2012, the largest single-year drop in the "carbon intensity" of the U.S. economy since recordkeeping began in 1949.

EIA says a significant shift from coal to natural gas to generate electricity, coupled with steady improvements in vehicle efficiency, could play key roles in cutting energy use and CO₂ emissions in coming years.