Natural gas could be considered the most environmentally friendly fossil fuel, because it has the lowest CO2
emissions per unit of energy and because it is suitable for use in high efficiency combined cycle power stations. For an equivalent amount of
heat, burning natural gas produces about 30 percent less carbon dioxide than burning petroleum and about 45 per cent less than burning coal. On
a per kilometre transported basis, emissions from LNG are lower than piped natural gas, which is a particular issue in Europe, where
significant amounts of gas are piped several thousand kilometres from Russia. However, emissions from natural gas transported as LNG are higher
than for natural gas produced locally to the point of combustion as emissions associated with transport are lower for the latter. However, on
the West Coast of the United States, where up to three new LNG importation terminals were proposed prior to the U.S. fracking boom,
environmental groups, such as Pacific Environment, Ratepayers for Affordable Clean Energy (RACE), and Rising Tide had moved to oppose them.
They claimed that, while natural gas power plants emit approximately half the carbon dioxide of an equivalent coal power plant, the natural gas
combustion required to produce and transport LNG to the plants adds 20 to 40 percent more carbon dioxide than burning natural gas alone. A 2015
peer reviewed study evaluated the full end to end life cycle of LNG produced in the U.S. and consumed in Europe or Asia. It concluded that
global CO2 production would be reduced due to the resulting reduction in other fossil fuels burned.