Fracking could accelerate global warming
By Fred Pearce (NewScientist) - August 12, 2013
The row over fracking for natural gas has hit the UK, with protests over plans in the village of Balcombe. Could they have a point? Studies are suggesting fracking could accelerate climate change, rather than slow it.
The case for fracking rests on its reputed ability to stem global warming. Burning gas emits half as much planet-warming carbon dioxide as an equivalent amount of coal. That is why, after embracing fracking, CO2 emissions have fallen in the US.
But leading climate scientists are warning that this benefit is illusory. Tom Wigley of the National Center for Atmospheric Research in Boulder, Colorado, concluded in a recent study that substituting gas for coal increases rather than decreases the rate of warming for many decades (Climatic Change, doi.org/dv4kbp).
Firstly, burning coal releases a lot of sulphur dioxide and black carbon. These cool the climate, offsetting up to 40 per cent of the warming effect of burning coal, Wigley told a recent conference of the Breakthrough Institute think tank in Sausalito, California.
Second, fracking technology – which involves pumping water at high pressure into shale beds to release trapped gas – also leaks methane into the atmosphere. Methane is a much more potent greenhouse gas than CO2 and Wigley says that switching from coal to gas could only bring benefits this century if leakage rates get below 2 per cent. If rates are at 10 per cent – the top end of current US estimates – the gas would deliver extra warming until the mid-22nd century.
A recent review by the UN Environment Programme agreed that emissions from fracking and other unconventional sources of natural gas could boost warming initially, and would only be comparable to coal over a 100-year timescale.
Another concern was raised at the Sausalito conference: methane may not stop leaking when the fracking wells are sealed. According to Carl Pope, former head of the Sierra Club – an environmental organisation in the US – the seals on tens of thousands of wells may be a methane time bomb. Drilling companies seal disused wells with cement to prevent leaks of any remaining methane. “North American cement lasts for 50 to 100 years,” said Pope. “What will happen to the wells and the methane as the well seals and casings begin to degrade?”