Risky predictions

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flood

Risk is a much mis-understood word.  In a technical sense, it is the probability of something happening multiplied by the consequences when it does [see post on Risk Definition, September 20th, 2012].  Tight regulation and good engineering could reduce the probability of earthquakes induced by fracking and such earthquakes tend not to produce structural damage, i.e. low consequences, so perhaps it is reasonable to conclude that the risks are low because two small quantities multiplied together do not produce a big quantity [see last week’s post on ‘Fracking’, 28th August, 2013].

The more common definition of risk is the probability of a loss, injury or damage occurring, i.e. severity is ignored.  Probability is used to describe the frequency of occurence of an event.  A classic example is tossing a fair coin, which will come down heads 50% of the time.  This is a simple game of chance that can be played repeatedly to establish the frequency of the event.  It is impractical to use this approach to establish the probability of fracking causing an earthquake, so instead engineers and scientists must simulate the event using computer models.  One approach to simulation is to generate a set of models, each based on slightly different set of realistic conditions and assumptions, and look at what percentage of the models predict earthquakes, which can be equated to the probability of a fracking-induced earthquake.  When the set of conditions is generated randomly, this approach is known as Monte Carlo simulation.  Weather forecasters use simulations of this type to predict the probability of rain or sunshine tomorrow.

The reliability of a simulation depends on the model adequately describing the physical world.  We can test this (known as validating the model) by comparing predicted outcomes with real-world outcomes [see post on 18th September, 2012 on ‘model validation’].  The quality of the comparison can be expressed as a level of confidence usually as a percentage.  Crudely speaking, this percentage can be equated to the frequency with which the model will correctly predict an event, i.e. the probability that the model is reliable, so if we are 90% confident then we would expect the model to correctly predict an event 9 out of 10 times. In other words, there would be a 10% ‘risk’ that the model could wrong.

In practice we cannot easily calculate the probability of a fracking-induced earthquake because it is such a complex process. Validating a model of fracking is also a challenge because of the lack of real examples so that establishing confidence is difficult.  As a consequence, we tend be left weighing unquantified risks in a subjective manner, which is why there is so much debate.

If you made it this far – well done and thank you!   If you want more on weather forecasting and extending these ideas to economic forecasting see  John Kay’s article in the Financial Times on August 14th, 2013 entitled ‘Spotting a banking crisis is not like predicting the weather’ [ http://www.ft.com/cms/s/0/fdd0c5bc-0367-11e3-b871-00144feab7de.html#axzz2dNrTKPDy ].

Fracking

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The British Prime Minister, David Cameron has argued in an article in the Sunday Telegraph (on August 11th, 2013) that if we don’t back fracking technology then the country will miss an opportunity to help families with their bills and make the country more competitive.  In his article the Prime Minister only makes the economic case in favour of using fracking to extract shale gas.  He completely ignores the environmental costs of these economic gains, which will always be present as in any industrial process – the second law of thermodynamics tells us to expect these costs – a form of increased entropy.  The environmental costs of fracking are still disputed.  Companies and politicians with something to gain from its successful implementation argue that the costs are very low or insignificant.  However, recent research has concluded that more than 100 earthquakes were triggered in a single year in Ohio due to fracking-related activities (J. Geophysical Research: Solid Earth, doi.org/nh5).  The largest of these quakes was of magnitude 3.9 and was caused by pumping pressurised waste water into a deep well.  There are also concerns that waste water from fracking might contaminate groundwater.

A joint report of the Royal Society and the Royal Academy of Engineering has concluded that the fracking process can be successfully managed without significant risks to the environment or society.  However, in France fracking has been banned.  So, the arguments flow in both directions.  As a society we are addicted to energy, and fossil fuels in particular, and hence we need sources of oil and gas.  The risks involved in extracting shale gas by fracking are probably no greater than those associated with oil or natural gas; its just that they tend to occur closer to people’s backyard, which makes people more sensitive to them.  Actually, the technology has been around and used for a long time; see John Kemp’s column at Reuters for an explanation of the process and its history.  However, if we intend to use it on a larger scale then we need to guard against unexpected consequences and be ready to deal with the mess when things go wrong.  When engineers succeed in these two goals then no one will notice but when they fail the public and many politicians will be quick to attribute blame to them, whereas it likely will be our addiction to fossil fuel that is to blame.

Detroit

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978000655083970256Last week we drove from the south through downtown Detroit on Interstate 75.  Approaching from a distance along the shore of Lake Erie and the banks of the Detroit river, the city looks like many others in the US with glass-clad towers clustered together and stretching towards the clear blue sky.  Close-up and beyond the glass skyscrapers, Detroit offers a different view of derelict apartment blocks, factory buildings and offices covered in graffiti with weeds growing out of them.  These are not isolated buildings but whole city blocks.  It is reminiscent of Hadron in Doris Lessing’s book ‘Mara and Dann’, in which twenty-five towers built for city administrators are left abandoned in preference for fine houses in large gardens.  The mental picture that our drive brought to mind was from Lessing’s book; however, in searching out the book at home I remembered a similar image drawn by JG Ballard in ‘High Rise’ in which civilised life in a 42-storey degenerates as residents abandon all moral and social conventions and a hunter/gatherer culture of competing gangs developed.

Of course Detroit is infamous for having recently become the largest municipal bankruptcy when it filled for Chapter 9 Bankruptcy on July 18th, 2013.  However, not all is doom and gloom in Detroit; it might be suffering from entropic decay but they know how to conserve energy (available energy).  At Detroit  Metropolitan Airport they are replacing more than 6000 light fixtures with LED (light emitting diodes) lights in the parking structures (multi-storey car parks) as well as adding an extra thousand for a total cost of $6.2 million (£4M).  It is anticipated that the resultant reduction in energy consumption will be 7,345,000 kilowatt hours (kWh) worth about $1.2 million per year (£0.77M).  According to Ali Dib, Director of Infrastructure & Engineering for Wayne County Airport Authority, the energy saved by the light replacements will be “equivalent to powering 880 U.S. households for one year, and the reduction of 7,000 metric tons of CO2 per year is equal to taking 1,350 passenger vehicles off the road.” Not something they would be very happy about you doing in the ‘Motor Capital of the World’.  So the other way of looking at the CO2 production saved is that it is equivalent to  25,400,000 passenger air miles not flown or a thousand round-the-world flights.

Oh, and the LEDs will only need changing every ten years instead of every thirteen months for the current light bulbs.

For ‘Mara and Dann’ see: http://www.dorislessing.org/maraand.html And for reviews: http://www.nytimes.com/books/99/01/10/reviews/990110.10upch.html or http://www.theguardian.com/books/1999/may/29/books.guardianreview27

For ‘High Rise’ see: http://www.jgballard.ca/criticism/highrise.html

Information on changing light fixtures from The Metropolitan dEtroit, August 2013 (p.11) and http://www.themetropolitandetroit.com/

Passenger air miles CO2 production from http://www.transportdirect.info/Web2/JourneyPlanning/JourneyEmissionsCompare.aspx

I and the village

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'I and the village' by Chagall

‘I and the village’ by Chagall

Last week’s post ended up a bit heavier, both in size and content, than I intend most posts to be so I thought this week’s should be short.

Recently, I visited the exhibition of Marc Chagall’s paintings at the Tate Liverpool and was particular inspired by ‘I and the Village’, which was painted in Paris in 1911 although Chagall was born in a small village in Belarus.  Apparently, the painting signifies the interconnectivity of human life and the surrounding natural world – notice the fine line connecting the eyes of the peasant and the animal also the peasant holding a sprig of a tree.  The orbits of the earth and moon are suggested by the circular shapes in the painting, which perhaps also represent the cyclical nature of life.

As you might guess from my posts over the last year, these ideas resonant with my own approach to our interaction with the earth and the natural resources available to us.  I like the layers of connections and interacting activities illustrated in the painting, including many that are not immediately obvious, just as in life.

The painting is part of the collection of the MoMA in New York [http://www.moma.org/collection/object.php?object_id=78984] but is part of the Chagall: Modern Master Exhibition at the Tate Liverpool until October 6th, 2013 [http://www.tate.org.uk/whats-on/tate-liverpool/exhibition/chagall-modern-master] for which it is their poster picture.  Either website will give you a better picture than the thumbnail above, or you could go and see it in person…