Leaks of methane, a highly potent greenhouse gas, during natural gas production and transportation can offset some of the climate benefits of switching from coal to gas. Some studies suggest that life-cycle emissions of shale gas may be similar or even higher than for coal depending on leakage rates.
Substituting gas for coal for power generation has been the primary driver of US emissions reductions in recent years. However, the pace of this substitution is slowing as coal retirements plateau and renewable energy becomes increasingly competitive. Continuing this trend will require stronger policies that prioritize low-carbon energy sources over fossil fuels.
Increased gas production can also lead to increased demand for energy, which could offset emissions savings. If natural gas is seen as a cheap and abundant energy source, it could discourage investment in low-carbon technologies and prolong the use of fossil fuels.
Some argue that increased domestic gas production can displace imports, reducing emissions associated with transportation and liquefaction of LNG. However, this assumes that exported gas would have been consumed in an equally carbon-intensive way. In reality, much of the exported gas would likely be used in countries that have less stringent climate policies than the United States.
