Merely making natural gas more abundant may do little, if anything, to curb carbon dioxide emissions. On this point, analysts are in remarkable agreement. Between 2011 and 2013, a group at Stanford brought together 14 expert teams of energy modelers to each independently simulate the impact of booming shale gas production on U.S. carbon dioxide emissions over the next 20 years. Half found that more shale gas ultimately meant lower emissions—but the other half found the opposite. None of the teams concluded that shale gas would do much to U.S. emissions over that time unless new energy policies were put in place.I would set this down in the positive realm; if part of the reason gas doesn't reduce CO2 emissions is that it leads to more economic growth, wouldn't we rather have the growth than not? The richer we get, the better we can afford investments in new technologies that will lead to truly renewable energy.
Why? Increasing shale gas supplies does two simple things to cut emissions. It shoves aside coal for electric power generation. It also (much more modestly) replaces some gasoline and diesel in cars and trucks. But four forces push in the other direction. Cheaper gas boosts economic growth, and a bigger economy means more emissions. Low-priced gas gives an edge to industries that are heavy energy users and big emitters. It also hurts lower-carbon competitors, like renewable energy and nuclear power, just as it harms higher-carbon coal and oil. Cheaper gas also means that consumers will use more of it. Analysts consistently observe that the forces pushing in both directions mostly cancel each other out.
To get quickly to a low-carbon economy, we need government action; fracking won't do it, nor will a fad for electric cars. But a carbon tax would.