In the first of a two-part debate, the Shell Professor of Earth Sciences at Oxford throws down the gauntlet in defence of a practice that has provoked intense opposition.

Fracking: Safer than you thinkHydraulic fracturing, or ‘fracking’, is a mining technology in which hydraulically pressurised liquid is used to crack rock, thereby allowing the recovery of hydrocarbons such as gas and oil. Almost no issue of our times has aroused as much heated debate as fracking, to the point where the real issues are almost overwhelmed by Hollywood films, lobbying groups and geo-political arguments. Here we present the first half of a two-part debate.

FOR: Joe Cartwright

Fracking: Safer than you think

Dr Joe Cartwright (pictured right; DPhil in rift systems, 1988) was appointed the Shell Professor of Earth Sciences at Oxford in 2012. He worked for Shell International as an exploration geophysicist, was at Imperial College as a Senior Lecturer until 1999, and was appointed Honorary Professor of the Institut Français du Petrole in 1998.

Fracking has already been used in more than two million boreholes so is hardly a new and unproven methodology. For instance, fracking is routinely used to enhance recovery of oil and gas from many conventional reservoirs of sandstone and shale, such as, for example, in Europe’s largest onshore oil field in Dorset, Wytch Farm, nestled in the beautiful New Forest. The legitimate concerns relating to fracking are no greater than would apply to any industrial operation, and are addressed by the right regulatory framework. But there is huge public fear and even unrest in many countries and indeed, in the US itself, at the prospect of fracking coming to ‘our community’.

Hydraulic fracturing of a shale gas reservoir involves drilling into the reservoir and pumping fluid into it at sufficiently high pressure to overcome the natural tensile strength, plus the confining stress. There is nothing intrinsically dangerous about pumping fluid into the deep subsurface at high pressure, provided the well is monitored carefully throughout. The resulting minor ‘earthquakes’ are tiny, relative to destructive earthquakes, and smaller than even those caused by mining operations. Fracking requires large volumes of water, but on a scale comparable to many other industrial activities.

In countries such as the UK and the USA, the regulatory framework for onshore drilling operations is sufficiently tight to allay fears. As we have seen over the years with conventional oil and gas drilling operations, accidents can and do happen. But such accidents are very rare compared to the scale of the activity.

There is another concern: that the chemicals being incorporated with water and sand into the fracking fluid will eventually penetrate groundwater aquifers. This is a fear that rests on a failure to grasp the scale of fracking. A typical fracture is less than a centimetre across and no more than 200 to 300 metres tall. Because shale gas reservoirs are only exploited at depths of 2 to 3km below the surface, and groundwater aquifers are typically a few hundred metres beneath the surface, the likelihood of fractures propagating anywhere near the water supply is extremely small. The greatest risk to groundwater comes instead from poor drilling methods, and particularly from poor quality cement lining of the borehole, which is a recognised problem for all drilling operations and for which regulations are already specifically designed. The chemicals used in fracking fluid also amount to about one per cent of the total pumped volume, and are strictly controlled in the US and UK.

Methane leakage to the atmosphere is not well quantified at present, partly because of the paucity of data on natural leakage of methane from the deep subsurface into shallow aquifers and to the surface, but this does need careful monitoring in the future.

Without a doubt, the greatest risk to communities where fracking operations would be undertaken comes not from pollution from drilling, or from induced seismicity, but from the vastly increased road traffic that would be required to supply the drill site. Only local communities can judge whether this disruption is justified by the privileges of living in a highly developed society, fuelled at least for the time being in large measure by oil and gas.

This article first appeared in the Michaelmas 2014 issue of Oxford Today. Read the full issue online here, or download in pdf, iPhone/iPad or Android format. Image of oilfield © Christopher Halloran /


By Peter Newman

Crisp, accurate and sane. And I think many communities would tolerate the surface disruption during drill site preparation and drilling, at least if adequately and directly compensated. But I fear the biggest obstacle is deep-seated public distrust of the extractive industries, which will cause extraordinary political and planning delays, such that we may never get close to properly evaluating, and potentially exploiting, this resource in the UK.

By David Keppel

It is sad to see "the Shell Professor of Earth Sciences" defend fracking and dismiss the climate-disastrous issue of methane leakage by saying it "is not well quantified at present." Is lack of data sufficient reason to plunge ahead in an activity that could have long term, devastating impact?

Oxford University must ponder the tremendous responsibility that goes with its preeminent position and think very carefully about professorships endowed by corporate interests with an agenda that may clash with the public good.

David Keppel, M.A. (Winchester Scholar at New College, 1976-9)

By K.B.Sykes

This appears to be a very balanced article - brief yet to the point. I was particularly interested to note the great difference in depth of the fracking process and the surface water aquifers (the pollution risk of which is often put forward as a strong argument against fracking). This information is very helpful in assessing risks. I look forward to the article "against".

By Clifford Peterson

As a lawyer, I know that a judge would weigh an expert opinion in light of the parties the expert works for or is funded by. For example, I was on a case where a judge discounted an expert's opinion because the expert's laboratory received funds from the company in whose favor the expert was testifying. I don't impugn anybody's integrity here (nor did the judge in that case). It's just a matter of what might be called intellectual hygiene, and I note that Professor Cartwright worked for Shell and holds a chair endowed by Shell. I look forward to the upcoming "Case Against Fracking" in OT.

By Phil Gordon

It's a welcome relief to read a commentary on the subject based on knowledge and science.

By Matt M

Fracking is a potent greenhouse gas emitter. Thirty times more methane is released than from conventional gas production and methane is 34 times more efficient at trapping heat than carbon dioxide. Once you burn the fracked gas, you have a process that could have as much global warming impact as burning coal. For that reason alone this gas should stay in the ground. Add in a risk of groundwater contamination, which even if we accept (which I do not) is "extremely small", then it's seems to me simple idiocy to allow fracking to go ahead.

By Chris Southworth

The problem with fracing isn't technical. It’s that it unlocks vast new sources of hydrocarbons for society to use, which is an anathema to those who campaign for lower energy use and only renewable sources. Hence, it should be no surprise then that fracing itself is portrayed as a new 'frightening' technology that will pollute your water and steal your children. After all, the court of public opinion outweighs the technical case every time.

By Donald Rudalevige

The article itself is fair and reasonable. However, there is a naive trust in regulations and the enforcement of those regulations. Groundwater in Pennsylvania has already been compromised in numerous communities, polluting wells and leaving residents with contaminated drinking/irrigation water. As we saw in the Gulf spill, regulations are only as good as those abiding - or not - by them.

By Dr. Steb Fisher

I hope that the next article you publish on this crucial question will contain a much high proportion of scientific evidence, rather than the opinions of someone with such close ties to the oil and gas industry.

By John Speller

Don't you think a professor who had previously worked for Shell and occupies a chair funded by Shell might not be the most disinterested of commentators?

By RH Findlay

As a geologist with 40 years experience and structural geology being a speciality, I know one thing. Natural and induced fracture systems are unpredictable in location, number and size, albeit we can make sub-scientific guesses.Groundwater is our most important buried mineral resource and there is no way a geologist can make blanket predictions that the chemicals and gases arising out of fracking, and in particular for coal-seam gas from shallow coal measures, cannot get into the groundwater.

In addition, fracking requires vast amounts of water, in the megalitres, to operate a well. This water is better used for irrigation and drinking, particularly in drought-afflicted areas, such as California, and indeed Australia where fracking is occurring for shallow coal-seam gas..

Finally, the USA's experience has been exactly contrary to that advocated by Prof Cartwright. Water supplies are being polluted, gas is getting into groundwater and is coming out of some people's taps, and the companies involved are dumping polluted waste-water back into the ground. And of course, there is a steady escape of the greenhouse gas, methane, to the air. All this is on record.

There are better ways of boiling a kettle for a cup of unpolluted tea than using shale gas or coal-seam gas obtained by fracking. And in view of anthropogenic global heating, perhaps we need to wean ourselves away from hydrocarbons as fuel.

RH Findlay (SEH 1968)

By David McAvoy

I would have more confidence in Professor Cartwright's reassurances if his Chair were not sponsored by Shell.

By David Leighton

As a former oil industry employee and Shell shareholder I have no quarrel with Dr Cartwright's article. What concerns me though is that investment in widespread fracking will divert attention from the development of truly long-term energy sources. These must, I feel, be invested in energetically both for sustainability and for political security.

By Ian Byrne

As a number of the above comments show, it's not really possible to view fracking in isolation from wider environmental issues, even though the direct risks from the process may be relatively low, mainly around pollution of ground water and direct emissions of methane. But the bigger issues are much more severe - use of finite (or very slowly replenishing) aquifers in some parts of the world, such as N Dakota; adding to the global stock of extractable fossil fuels (which would not be a problem if it meant that some other, higher carbon sources were to be permanently "frozen", but this seems most unlikely) and the knock-on effects of cheaper gas in the US - which has led to plummeting gas prices, in turn leading to less investment in energy efficiency and lower carbon renewables, and greater exports of coal for use in power generation in Europe (so our own National Grid derived electricity has had a higher carbon content).

Of course not all these effects would apply to fracking here in the UK; but I'd have greater confidence in the article as a whole if it didn't incorrectly locate Wytch Farm as being "in the beautiful New Forest" at the very start. It isn't; it's on the equally beautiful Isle of Purbeck, about 20 miles West of the New Forest!

By Timothy Roberts

The objections to fracking are religious, not scientific - the religion being environmentalism. More scepticism would be in order. Cheaper energy decreases poverty and speeds up development.

By John MacLean

Dr. Cartwright's argument seems three-fold:

1) Fracking is no more dangerous than other means of oil and gas extraction, though accidents will happen. Colorado alone now averages two spills a day. I take scant comfort from this.

2) Fracking is well regulated. This is simply not true. In the US, the industry has fought disclosure, let alone regulation tooth and nail. What regulation there is has often been written by the industry itself. The government offices tasked with oversight are deliberately underfunded and understaffed.

3) Oil and gas are the only way to enjoy "the privileges of living in a highly developed society," for the present and immediate future. How then does Germany enjoy these privileges using 74% renewable energy? In the US, where oil and gas companies enjoy lavish tax benefits for development, these same companies have lobbied to eliminate all tax incentives for the use of wind and solar. In several states they have succeeded, doing all they can to insure that the immediate future stretches on indefinitely.

The article also makes no mention of the substance given the orwellian names "flowback" and "manufactured water." Since what goes down must come up, all those millions of gallons of fresh drinking water now laced with chemicals and pumped into the wells comes back up to be stored in open, unlined pits - that leak.

By Andrew M

I do appreciate a "FOR" argument from a knowledgable source. However,
(1) After reading comments by others in-the-know, the initial arguments in the article appear to contain a number of half-truths; not to mention complete avoidance of the elephant in the room: climate change, "the biggest global health threat of the 21st century" [DOI:]

(2) There's an implication in the article that, without 'tight regulatory frameworks' imposed by certain governments, the oil companies would care even less about environmental risks. It is perhaps unsurprising that the public are often distrustful of large multinationals who appear to be making lots of money, whilst risking ruining local and global environments. Mistrust may also stem from previous allegations about unethical practices of various oil companies.

(3) As in many journals, are authors required to declare potential conflicts of interest in OT?

By James Alexander

I wonder what the Sierra Club Professor of Earth Sciences at Oxford thinks. As a graduate of Oxford, I am dismayed that the institution has soiled its impartiality on a key environmental issue by selling the oil and gas industry a sponsorship under the thinly veiled title of 'Shell Professor of Earth Sciences' followed by promoting articles headlined "Fracking: Safer than you think". We very much need an objective debate and, regardless of your position, it would be far easier for an institution like Oxford to lead such a discussion as long as all sides have confidence in its unbiased stance.

By Peter Waite (CC...

On one Sunday in May 2014 Germany managed to produce 74% of its electricity from renewables. This happened on a day when the sun shone and the wind blew and power demand from industry was less than a weekday and domestic demand would be lower than in peak winter. Overall Germany did well, in the first quarter of 2014 generating 27% of its electricity from renewables but this is a much smaller percentage than quoted above. (see for example ).
Selective numbers are quoted by both sides of the argument in an inappropriate manner.
There are technologies available to remove CO2 efficiently from the generation of electricity using fossil fuels, including post combustion capture, which effectively generates hydrogen as a fuel for gas turbines. The advantage of this could be to provide an alternative to fossil hydrocarbon fuels for transport, for which suitable renewables are in much shorter supply.
There are risks from all types of energy generation, whether to the workforce employed in building and maintaining them or the public in the vicinity (wind turbines suffer catastrophic failure and collapse, with a risk from shedding turbine blades too).
Shale gas is likely to be less damaging than coal and renewables cannot yet meet all our energy demands (for electricity, heating and transport). May be in the longer term the problems of economical storage of energy from renewables and conversion to transport fuel will be solved but unfortunately this position is some time away.

By Grant A. Brown

The energy consumed in scare-mongering over fracking would be better spent investigating the environmental impacts of "renewables" such as wind power: (1) more concrete and steel is used to construct turbines, per kw-hr generated; (2) more birds and bats killed than in the tailings ponds in Alberta's oil patch; (3) the vast landscape destruction in China caused by mining rare earth metals for the permanent magnets in the turbines; and (4) the fact that wind power must be backed up with conventional power plants anyway, for use during calm days. What is that saying about "good intentions"?

By J. Shankleman

The points about climate change and about negative local impacts from traffic are well made. However as long as we continue to use oil and gas, better it is produced in countries that have the capability and will to manage the manageable impacts than countries such as Nigeria which do not have effective environmental controls and where the country's riches are extracted in a way that produces no development benefits. If we use the fuels, we should accept the impacts.

By Noam Vogt-Vincent

I really feel like this is missing the point. It definitely does appear to be the case that safety fears about fracking have been exaggerated and it is certainly not helpful that so many opponents of fracking use fears of earthquakes and water contamination as the bulk of their arguments. The real issue with fracking is that it is yet more investment in fossil fuels at a point where we already know that most of our existing reserves will have to remain in the ground if we want to stick to internationally agreed carbon emissions targets. Furthermore, whilst it may be true that methane leakage "is not well quantified", it certainly does exist and only adds to the problem of hydrocarbon combustion.

Shale gas is just a geopolitically convenient distraction from the kind of changes we need to be seeing in our energy infrastructure. The IPCC makes it very clear how little time we have left to start seriously reducing carbon emissions so the last thing we need is yet more investment in the root cause of the problem. It is completely correct that a transition to a less carbon intensive society will not be able to happen overnight but shale gas extraction will simply elongate this process. Why are we not instead investing in making renewables more practical rather than trying to support an industry that is intrinsically unsustainable?

By Tom Brown

I think it unfair to question Dr Cartwright's expert assessment of the risks on the basis that his Chair is sponsored by Shell. Note also that he does not dismiss the risks of methane leaks. But none of what he writes adds up to a convincing case as to why fracking should be licensed on a widespread basis in the UK. This is because the economics of fracking and to whom the economic benefits flow are not discussed, however because the volume of onshore fracked gas or oil will by no estimate be of the continental proportions to have an effect on market prices for gas delivered to the UK, and there is a massive global gas glut with existing pipeline and LPG terminal connectivity into the UK, the idea put about by some politicians that fracking would lead to lower gas prices is highly questionnable. The equity owners and high-yield lenders to the niche operators would be the principal beneficiaries; the extent of gain to the public exchequer is unclear, and have to be set against the cost of reinstatement of countryside after termination of operations if - as is very possible - this is not recoverable from the licensee in full and wear and tear of roads caused by the project. The public should also be aware that a fracking well will require connection to a gas compression station and the national transmission network. Further environmental impacts on air from flaring should also be considered. Thus, in my view while the safety of fracking per se does suggest rejection of the operation, a wider picture - including as others note how this can be reconciled with the urgent need to reduce CO2 emissions - must be considered, which could on a balanced view still lead to the conclusion that it is not appropriate for wide-scale onshore use in the UK, a much smaller country than the USA or Canada.

By David Somervell

Quite amazing that a University can 1) accept money from a company hell-bent on drilling against all the odds in the high Arctic Sea and 2) that they publish such a poorly framed and partial promotion of a contested technology. I'm surprised. Does not bode well.

By Pete Fry

It's always good to hear cogent arguments but this one does not make the cut: "The chemicals used in fracking fluid also amount to about one per cent of the total pumped volume, and are strictly controlled in the US and UK." Would the Shell Professor drink liquids that were only 1% arsenic or 1% cyanide? Moreover it is simply not true that the fluids are strictly controlled in the US. The US government exempted fracking fluids from the clean water act. If these fluids are truly benign, why would the exemption be deemed necessary by the energy industry?

By Michael Roberts

A fine short article. Apt as I live in Lancs a centre for fractivists causing mayhem with scaremongering and misrepresentation.
I hope all those who oppose fracking do NOT use any fossil fuels directly or indirectly, even a bicycle!!

By Finn Jackson (T...

You can see several of the main myths about fracking debunked here:

I think it covers pretty much all of the points this article makes, but going through them one by one:
- all wells leak eventually
- the fracking in Dorset is different from the fracking they want to do in Yorkshire (just as sea water, tap water, river water, puddle water, and Evian are all "water" --- but different)
- earthquakes are caused more by the reinjection of 'spent' fluids, rather than the fracking process, but he doesn't mention that
- fracking "uses" water at similar scale to other industrial uses, such as cooling towers. However, the other uses don't pollute the water and make it undrinkable, they simply move it to a different place and then return it in the same form to the water cycle. eg cooling towers and farming.
- The regulatory framework does not change the laws of concrete. There is good evidence of this in a short video of Dr Anthony Ingraffea on the videos page of the above website.
- Also the regulatory framework is meaningless if it is not enforced, which has been the track record so far in the UK: planning agreements (for example in the East Riding of Yorkshire) have been flouted and ignored several times.
- ALL wells leak eventually, more than 6% in the first year, which with 8 pads per square mile and up to 20 wells per pad means that everybody in the area would be within one mile of a leaking well after 12 months.
- It does not matter that the fracks might not reach the aquifer... The polluting chemicals migrate up the sides of the well (see Ingraffea video)
- I don't care if the fracking fluids are "only 1%" of the total. I don't want it in my drinking water. Once they are in the aquifer they can't be taken out.
- Methane leakage (Ingraffea video again) has been measured and shown that fracked gas is worse climate impacts than coal.
- To say that the greatest threat is from "vastly increased" traffic not pollution is not the view of those living nearby. The traffic would be devastating, yes, but the pollution is worse, as the hard evidence from Queensland and North Dakota shows.
- Finally Dr Cartwright writes, "Only local communities can judge whether this disruption is justified by the privileges of living in a highly developed society, fuelled at least for the time being in large measure by oil and gas." The local community would bear the brunt. The oil companies and their owners would reap the privileges. Major banks are now telling investors that by 2020 (even in the UK) it will be cheaper to generate electricity from solar than from gas. Alternative ways of generating the energy we need without the negative impacts are here now. Let's embrace them.

By Marjorie Nye

As Lancashire County Council are about to make their decision to allow permits to Cuadrilla to build and operate the first 2 shale gas sites in Lancashire, the residents of the nearby villages[ if the permits are allowed,] will be subjected to 24/7 drilling as well as up to 50 lorries passing along the narrow country lanes in front of their homes. Any one wanting to move to these rural beauty spots is immediately turned off when they realise the rigs will be in fields just a few metres from their homes!
Those wanting to sell their homes cannot sell them because of the environmental damage and noise that will be ongoing for years. The industrialisation of the country side is one thing that cannot be sustained. That is before the other dangers from Methane escapes, Radon Gas emissions and polluted water is taken into account. If we can't learn the lessons of the dangers to health and the environment that are now being assessed in the US with moratoriums now in place in many states, then we will learn the hard way yet again. It is interesting to read the ex employee from Shell stating the safety of his company in Shale gas exploration and extraction, Shell have backed out of Shale gas now so why one wonders when they sold their Shale assets last year what was behind the decision? Regulation is very weak in the industry and with all the cut backs in Local Authorities now who will spend the money on regular inspections to check cement bonds, leakages emissions etc etc

By Jim Buckee

The article is a welcome dose of reality: fracks are small relative to the depth of the well and cannot travel the kilometres of rock needed to reach aquifers. The author does not, however, address who gets the royalty payments, a major incentive for landowners in the US.