For more than ten years scientists have been raising concerns about air pollution from fracking. A worrying development emerged in 2009 when a new type of ozone smog appeared across the Uinta Basin in the US state of Utah. This is a large, flat area bordered by mountains to the north and east, and its winters can be cold. During one notable event between 20 and 30 centimetres of snow covered the ground, but ozone rose to concentrations normally only seen in hot summers. It could not be more unlike the conditions that led to the Los Angeles smogs.
Something similar had been seen five years before in neighbouring Wyoming, as a result of which the state breached US ozone standards. With this in mind, researchers in Utah set about finding the source. They started with air pollution sources that they knew about, but it simply did not add up.
As in Wyoming, the shales in the Uinta Basin in Utah had recently been developed for fracking. This involves injecting liquids underground to fracture the rock in order to extract oil and gas. Huge controversy, including the arrest of the Green Party leader Caroline Lucas, surrounded the drilling of just two pilot wells in the UK – one in the northwest of England, near the seaside town of Blackpool, and another in the southeastern county of Sussex. According to the Washington Post, 137,000 new wells were drilled in the US in just six years (2010 to 2016). It is impossible to estimate how much gas leaked by looking individually at each well and the miles of pipework, pumps and machinery. Instead researchers have flown over the oil and gas fields with instrumented aircraft, measuring what was coming from the ground below them. One flight over part of the Uinta Basin revealed the answer to the winter ozone. A lot more methane was leaking from the wells than had been thought – an extra 40 per cent. In winter, this was being trapped in the cold air layers close to the ground, forming ozone as the low-angle sun was reflected off the snow.
More flights over US shale gas fields revealed large methane sources, but these areas also have methane-producing cattle farms. The shale gas plants could simply blame the farmers. The two sources therefore needed to be separated in the data. Usefully for this type of experiment, shale gas also contains ethane, which does not come from natural sources such as farming. Looking at ethane and methane together showed that shale gas and oil extraction were overwhelmingly the dominant source, not farmers. Some active drilling areas were notable ‘super-emitters’, suggesting that this phase of shale gas production is the worst of all.
Ethane can remain in the air for months, making it useful as a means of tracing leakages from natural gas as air travels around the world. Global Atmosphere Watch has been measuring the composition of our air for over 30 years. One of its sites is located on top of the Jungfraujoch in the Alps. Overall the news from here had been good. Better controls on the European gas industry had been leading to slow reductions in ethane since the 1980s. But suddenly in 2009, around the start of large-scale fracking in the US, the ethane trend reversed. Ethane started to increase, and not by a small amount. It was increasing by five per cent per year. This points to a big increase in the global methane leakage from natural gas use.
Looking at measurements from locations in remote places around the world from locations in remote places around the world, notable differences can be seen. Ethane is not increasing everywhere. At Lauder, on New Zealand’s South Island, the trend has continued gently downwards in common with most of the southern hemisphere. In the east of the US, at monitoring sites on Atlantic islands and across Western Europe, it is a different story. All these places have seen increases. Generally, air flows in an easterly direction around the world, so it looked as if the new sources lay in the US. This was confirmed by looking at propane, which is also found in oil and gas but has a shorter life in the atmosphere. Again, it was the Global Atmosphere Watch sites on the east of the US and in the Atlantic (Iceland, Cape Verde and the Canary Islands) that detected increases, but the gradient across the US was striking. There was a decrease in propane on the western side of the US but on the eastern side it had increased sharply. There can be little doubt that the huge expansion of natural gas and oil production across the US led to these increases. US methane leakage may be around twice the official estimates and it is having a global impact. There is clearly a need for better controls.
By 2020, fracking is projected to lead to between 200 and 800 extra premature deaths each year from ozone and particle pollution across the Marcellus and Utica shales in the Appalachian Basin, which have seen intensive leasing and drilling. This large area of the eastern US crosses several states. Fracking fever has swept through the most densely populated parts of Europe, including Denmark, Lithuania, Romania and especially Poland. With an increasing reliance on imported gas from Russia, and the desire to meet carbon emission targets, the pressure for shale gas exploitation will continue. Maybe there is a silver lining: if shale gas leads to the shutdown of polluting coal-burning industry and power plants or the displacement of extensive oil heating in cities such as New York, it could help curb urban air pollution. This, however, should not be used as a reason for poor controls on the natural gas industry.
One of the frequent justifications for fracking is the use of natural gas as a bridging fuel between coal and a low-carbon future. Certainly, burning natural gas for energy emits a lot less CO2 when compared with burning coal. However, natural gas is mostly methane, which has strong global warming effects in its own right. Natural gas therefore only provides climate benefits over coal if leakage is tightly controlled to no more than two to three per cent. Leakage rates of at least 0.18 to 2.8 per cent have been measured in flights over fracking wells even before the gas is distributed to users. It will therefore be hard for US fracked gas to be better for the climate than burning oil or coal.
It remains to be seen if the UK government’s decision on fracking is an electioneering ploy as opposition parties suggest or if it will have wider repercussions and spell the beginning of the end for this industry.
Gary Fuller is an air pollution scientist at King’s College London. His new book, The Invisible Killer: The Rising Global Threat of Air Pollution – and How We Can Fight Back, is out now in paperback from Melville House UK
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