The importance of this is that "100 years of gas" proponents (and of course the 100 years is bogus at anything like projected use, or even more if it takes the place of oil and coal) always claim that natural gas is relatively clean and (in the old days) produced less CO2 per unit of energy delivered than coal.
There are many problems with this claim, but one I had overlooked is Shale Gas is the dirtiest natural gas ever, not just in terms of producing enormous amounts of toxic waste, but in the CO2.
Much natural gas can leak out during fracking, right at the wellhead during various phases of the fracking process. And for global warming considerations, natural gas (methane) causes more than 10x as much global warming as CO2 itself.
And then there are the trucks. Any fracking operation involves trucking in vast amounts of water and chemicals, and then trucking out vast amounts of highly toxic spent fracking fluid. Those trucks typically burn oil and produce CO2.
So by some considerations, it seems likely that Shale Gas is as horrible as King Coal.
Other analysts point out the futility of using Natural Gas from fracking as a "transition fuel". We need to make the transition to renewable energy now, not after we've burned a bunch of other bad stuff, or built even more cities and infrastructure around an outdated energy model.