The problem, as yet unmentioned, with hydraulic fracturing, is not just the toxic nature of the chemicals used, or
the changes it creates in the ground.
The construction of fracking wells creates a long term (and by this I mean "forever") maintenance issue. At the surface it's easy enough to maintain the well casing, but below the surface, and especially where the well punches through confining layers, the wells can, do and will fail. In ten years, or fifty years, or one hundred years. We won't know abut it until we find contamination in aquifers.
Down the road (and after all the money's gone), it won't be the company who did the fracking paying to fix the broken well casing, and clean the contaminated aquifer. If the company still exists (and that in itself is a big if), most likely they will say "there's no proof we did it". Unfortunately for the National Party, there's Hansard showing they could have stopped fracking, and chose not to. They can't even use the "it seemed like a good idea, at the time" excuse.
I had to laugh at the Minister suggesting Mr Hughes was a hypocrite for opposing fracking, because Mr Hughes had surely, at some point in his lifetime, benefited from fossil fuels and therefore had no right to express a contrary opinion. Based on that logic, the National government have no right to restrict access to the government's largesse in the areas of welfare (for Ms Bennett) or state housing (for Mr Key). However, it's crap logic and National can legitimately make changes. All this means is that the arguments against the changes need to rely on things like logical arguments and quantifiable evidence.