In terms of carbon emissions, traditionally-derived natural gas
is less pollutive than other forms of fossil fuels. The Union of
Concerned Scientists reports that natural gas produces 43
percent and 30 percent fewer emissions per unit of energy
compared to coal and oil, respectively. This is very good news
considering it is estimated that 2,500 trillion cubic feet of
natural gas are located in the U.S. and Canada – thought to be
equal to a one-hundred year energy supply at current consumption
rates. However, a report by the Climatic Change Journal found
that carbon emissions from shale gas are at least 30 percent to
two times as great as those associated with traditional gas.
According to the study, “the higher emissions from shale gas
occur at the time wells are hydraulically fractured – as methane
escapes from flow-back return fluids – and during drill out
following the fracturing.” The report estimates that 3.6 to 7.9
percent of methane escapes during these processes. As methane is
a more potent greenhouse