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Chemical industry failing to stop emissions of super-strong greenhouse gas HFC-23 – new research

Posted on by amanda.woodman-hardy
The potent greenhouse gas HFC-23 is emitted from the industrial production of fluoroplastics and specific refrigerants.
Quality Stock Arts/Shutterstock

Emissions of a super-strong greenhouse gas could be substantially reduced if factories would properly implement existing “destruction technology” in certain industrial production processes. If operated properly, emissions of this greenhouse gas could be cut by at least 85% – that’s equivalent to 17% of carbon dioxide emissions from global aviation.

Our research, published today in the journal Nature, scrutinises emissions of one of the most potent hydrofluorocarbon (HFC) greenhouse gases, called trifluoromethane (HFC-23). One gram of HFC-23 in the atmosphere contributes as much to the greenhouse effect as 12kg of carbon dioxide.

This unwanted byproduct comes from the production of certain gases used as refrigerants and the manufacture of fluoropolymers (a class of plastic chemicals) such as polytetrafluoroethylene (PTFE), a key ingredient in most non-stick cookware.

black frying pan, single friend egg, dark background.
Fluoroplastics are used in the production of non-stick cookware.
J.Thasit/Shutterstock

More than 150 countries have pledged to significantly reduce their HFC-23 emissions as part of the 2016 Kigali Amendment to an international treaty called the Montreal Protocol on substances that deplete the ozone layer. The breakdown of HFCs in the atmosphere does not directly link to ozone depletion, but HFCs were introduced to replace ozone-depleting substances such as chloroflourocarbons (CFCs), so they have been included in this regulation.

HFCs are also strong greenhouse gases. While the Kigali Amendment aims to reduce emissions of widely used HFCs, an exceptional arrangement is made for HFC-23. Because HFC-23 is largely emitted from production processes and not from end-use applications, its destruction as a by-product is required “to the extent practicable” as of 2020 – that means as much as possible, but it’s a vague limit.

Even before 2020, many countries, including the biggest manufacturers of PTFE such as China, reported they had installed destruction technologies at PTFE factories and are successfully destroying HFC-23. In 2020, the reported global annual emissions of HFC-23 were only around 2,000 metric tonnes – but actual global emissions, derived from atmospheric measurements, amounted to around 16,000 metric tonnes.

To unravel this discrepancy between real and reported emissions, we analysed HFC-23 emissions from a major European PTFE factory in the Netherlands, which already operates destruction technologies – these include the incineration of harmful byproducts.

The aim of our experiment was to define what “practicable” actually means, and to identify how much HFC-23 can be easily destroyed by existing technology at a factory-wide scale, considering that emissions come from both the chimneys and leaks from other parts of the plant.

With the factory’s collaboration and the consent of the Dutch environment authorities, we released a controlled amount of a tracer gas directly next to the factory: this is a non-toxic, degradable gas that does not occur in the atmosphere. We then measured the concentrations of HFC-23, other byproducts of flouropolymer manufacture, and the released tracer at an observing site run by the Europe-wide greenhouse gas research centre, the Integrated Carbon Observation System, near the Dutch village of Cabauw.

This 213m-tall tower is located around 25km away from the factory. We knew exactly how much tracer we had released and how much of it arrived at the measuring point, so we could calculate the emissions of HFC-23 and other gases.

aerial shot of tall metal tower, green fields
Measurements of HFC-23 and the tracer were carried out at the 213m Cabauw measuring mast, operated by the Royal Netherlands Meteorological Institute.
ICOS RI/Tom Oudijk, Sander Karsen, Dennis Manda, CC BY-NC-ND

Results showed that even though our estimated emissions were higher than those reported by the factory, the technology at this particular factory was working properly and successfully destroying HFC-23.

Upscaling to global emissions

However, as the industrial manufacture of fluoropolymers is currently the major known source of HFC-23 to the atmosphere, we suspect that destruction technologies are not as effectively operated as reported by manufacturers.

Our findings indicate that if all factories globally were controlling emissions in the same way as the Dutch site, HFC-23 emissions could be cut by at least around 85%, representing emissions equivalent to 170 million metric tonnes of carbon dioxide per year. This reduction equates to almost one-fifth (17%) of carbon dioxide emissions generated by all aviation traffic.

Real and reported emissions of HFC-23

An independent auditing framework for fluoropolymer production would ensure that HFC-23 is destroyed properly at factories around the world. Targeted monitoring of greenhouse gas emissions resulting from the production of fluorochemicals would further the understanding of emission sources and ensure that countries are fully compliant under different international climate and environment agreements.

Our results show that destruction technologies can effectively be implemented – in this case, at factories producing fluoropolymers such as PTFE, to significantly reduce the emissions of a highly potent greenhouse gas.

This blog is written by Dr Dominique Rust, Research Associate, School of Chemistry, University of Bristol; Dr Kieran Stanley, Senior Research Fellow, School of Chemistry, University of Bristol, and Stephen Henne, Senior Scientist, Group Atmospheric Modelling and Remote Sensing, Swiss Federal Institute of Technology Zurich.  This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dr Kieran Stanley
Dr Dominique Rust

How fly fishing strengthens our connection with wildlife and fosters conservation efforts

Posted on by adele.hulin

Whether it’s to reset our mental health or simply to take time out from the hurly-burly of work and urban life, many of us head for oceans and rivers to enjoy their restorative capacities.

Encountering wild animals in these blue spaces contributes to the beneficial effects of being in nature and forms the basis of tourist economies the world over.

Yet, how does our presence affect the creatures that call blue spaces home, and how do encounters with wild species change our relationships with natural environments?

River and stones with green trees and shade
The River Lyd, Devon. Avi Shankar

For nearly a decade, we have been researching human interactions with wild trout and salmon in the context of fly fishing. We spent months immersed in river environments both in the UK (the Lyd and Tamar in Devon, and the Usk and Wye in Wales) and North America (the rivers of the Gaspe region, Quebec and Lewisburg, Pennsylvania). We went fishing, observed and interviewed fly fishers, and learned as much as we could about fish behaviour.

In our recent paper, we explain how human interactions with fish can result in three kinds of interspecies encounters that strengthen people’s connections with wildlife and natural environments.

Separated encounters

Most often, wild animals remain indifferent to humans, driven as they are by natural motivations to feed and breed, within environmental habitats that humans do not fully understand.

For instance, Duane, a novice fly fisher we interviewed in Pennsylvania, didn’t know that trout eat aquatic insects: “I didn’t know squat … flies actually come out of the water?”

This lack of understanding of other species often ensures that wild animals remain undisturbed by human presence. Yet the elusiveness of creatures such as trout and salmon can also motivate people to find out more about them.

Slippery encounters

To improve their chances of catching fish, fly fishers learn about fish behaviour, river environments and the life cycles of the insects that fish feed on.

Equipped with this knowledge, fly fishers become better able to locate trout and salmon, and to select and cast a near weightless imitation “fly” designed to mimic a fish’s insect food.

Learning and honing these skills is a lifelong project during which fly fishers become savvy hunters with heightened abilities to sense what is going on in the water. Equally, fish learn too, becoming shy and ready to slip away from human contact.

Sticky encounters

On the rare occasions that fish are hooked, humans and fish enter what we call a “sticky encounter”. The mixed emotions of catching a wild salmon are captured in Annetta’s field notes:

I look down at this beautiful, majestic being. The fish is a fresh, healthy, silver, bright female … I look at her, she looks back at me … She wrangles free. She’s on a mission to spawn in her home river. I stand up but I’m weak in the knees. Full of pride, humility, and guilt.

Over time, these intense experiences of eye-to-eye contact can inspire fly fishers to consider the welfare of fish.

A wild Usk brown trout in a net
Netted: a wild Usk brown trout – most fly fishers now carefully return their catch back into the river. Avi Shankar

Fly fishers now release the majority of the fish they catch. Moreover, one fly fisher we interviewed explained that he has entirely removed the hooks from his flies, declaring: “I don’t want to catch that fish. I caught so many in my life. I know what the feeling is like.”

Stewarding blue spaces

It may seem ironic that fly fishers become passionate about conserving fish and river environments by practising what many people consider to be a cruel sport. Yet, fly fishers have first-hand experience of declining fish numbers.

Some of our interviewees spoke of trout and salmon as “canaries in the coal mine” – a warning sign of how river ecosystems are threatened by pollution, overdevelopment and climate change. In response, organisations such as the Wild Trout Trust and the Atlantic Salmon Trust highlight the necessity for conservation.

With wild populations of animals declining globally, the presence of humans in blue spaces deserves scrutiny. Nevertheless, interspecies encounters can change the relationship between people, fish and rivers from one of human gratification to one of reciprocity, stewardship and care.

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This blog is written by Professor Avi Shankar, Professor of Consumer Research at the University of Bristol. It is republished from The Conversation under a Creative Commons license. Read the original article.

Avi Shankar standin in the street
Professor Avi Shankar

How do you manage a dam when there’s a tropical cyclone in Mozambique?

Posted on by amanda.woodman-hardy

Mozambique dam

I’d never given a huge amount of thought of what a dam manager did until I visited Pequenos Libombos dam in Mozambique in October 2023. Standing at the dam, in hot conditions, listening to the lived experience of people who work on the ground and explain what they do during a tropical cyclone leaves you with more understanding than any peer reviewed journal article. Context is everything. It’s why visiting the countries I’m researching is something I do given the chance.

That’s what members of Bristol projects REPRESA (co-led by Prof Elizabeth Kendon at University of Bristol & UK Met Office, Dr Luis Artur from Eduardo Mondlane University and Prof Francois Engelbrecht from University of the Witwatersrand) and SALIENT (led by Dr Rachel James, University of Bristol) did in October. The REPRESA project aims to understand compound tropical cyclone risks, impacts of tropical cyclones and improve early warning systems in Mozambique, Malawi and Madagascar. Seeing the research alignment in projects, the SALIENT team also joined. The SALIENT project aims to improve the characterisation and communication of future climate information for national adaptation planning in southern Africa.

On the field trip day, we travelled to Pequenos Libombos dam and heard from a government official from the Vila De Boane Municipality. It was this day where I had my epiphany that if I ever left academia, dam management is not my calling. Providing water to the local population is the dams primary role and it provides 2 million people within Maputo Province with access to water. That is more than 4 times the population of Bristol.

The management of Pequenos Libombos dam is difficult as there are many other people and industries to consider and keep safe and happy when making decisions. From the businesses who want to use the dam’s water for industrial purposes to the farming communities that are reliant on the water for irrigation, and hydroelectricity companies that want to use the dam to create energy to the communities downstream that may be flooded if the dam releases water too quickly. The dam catchment is also shared with 2 of Mozambique’s neighbouring countries; eSwatini and South Africa, adding another element of complexity to the dams management.

Management must carefully balance both periods of water surplus and deficit and Maputo has experienced numerous extreme weather events in recent years.  The 2015-2016 southern African drought impacted Central and Southern Mozambique and more recently the remnants of tropical cyclones in 2019, 2011, 2022 and 2023. During February 2023, Tropical Cyclone (TC) Freddy passed over Madagascar and southern Mozambique before returning a couple of weeks later to central Mozambique. It is thought to be the longest lived and have the highest accumulated cyclone energy of any cyclone on record, awaiting formal investigation from the World Meteorological Organization. Although TC Freddy didn’t directly pass over Pequenos Limbombos, its associated rainfall resulted in 250 mm of rainfall at the dam in one day. For context, the Bristol experiences 265mm rainfall, on average, in October, November and December combined. To avoid a breach of the dam, discharge was released at the maximum rate, which is more than 500 time more than normal.

Globally there is evidence that TCs and their impacts are being impacted by climate change. The frequency, intensity and storm tracks of TCs may be changing meanwhile, rising sea levels may lead to higher storm surges. Yet we know a limited amount about how tropical cyclones may act in a future with increased global sea surface and air temperatures.  TCs in the Indian Ocean are particularly under researched, but recent and frequent events have highlighted the importance of understanding TCs in a changing climate.

After hearing about the vast amount of rain that fell in February 2023, we walk past the disused hydroelectric generator that was forced to cease operation during the drought as it was no longer economically viable. It really hammered home the complexities faced when trying to manage such a huge piece of infrastructure during extreme events. Similarly, it is clear why research projects like REPRESA and SALIENT are needed to understand how tropical cyclones may behave in the future and explore how early warning systems and climate change adaptation can be strengthened.

Mozambique dam

The human side of extreme weather

After the talk at Pequenos Libombos Dam, we visited the Municipality of Vila de Boane. Vila de Boane is located roughly 15 km downstream from the dam and the River Umbuluzi passes through the municipality. The municipality experienced large scale flooding after the dam was forced to increase to maximum discharge during the February 2023 rainfall.

Despite already hearing about TC’s Freddy’s impacts at the dam, they were not as focused on the human impact. The leader of the municipality compellingly described how 16,000 people were impacted overnight, 6000 people were displaced and 6 people sadly died. The community water pump was destroyed, leaving people without water for 3 months. The municipality leader said he had never seen that amount of water passing through the municipality at such high speed before. Meanwhile, money that had been budgeted for development initiatives, had to be redirected to repair and response. It was not clear if extra money had been sourced for the development initiatives.

It was also highlighted that the increased release of water from the dam occurred over night with little warning. The municipality had been told to expect “above normal” rainfall and to avoid being close to rivers and move farming machinery further inland. But as the municipality leader questioned, what does “above normal” actually mean? People will perceive this message differently, which will influence how they act upon it. As part of the SALIENT research project, I am researching how we best communicate future climate information to decision makers and this anecdote will stay with me. It’s clear that improved communications are needed in both weather and climate services, something REPRESA is also aiming to research further.

Reflections and collaboration

After hearing about the vast amount of impacts the flooding had on Villa de Boane, we waited for our transport back to Maputo under the shade as it was too hot to stand in the sun. It was clear everyone from the REPRESA and SALIENT teams, both physical scientists and social scientists, had taken a lot from the field day. There was discussion about what the research should consider as well as the different angles that could be taken. It also fostered collaboration, SALIENT team member, Alan-Kennedy Asser, is providing the REPRESA team with analysis of precipitation trends from a multiple ensembles of climate models to characterise the range in future projections over the region. Meanwhile I spoke with some REPRESA team members in more depth about future climate information and will be providing risk communication training session in the future.

My personal key take away is that understanding the context and hearing the lived experiences of people working and living with extreme weather events enriches me as a researcher. Similarly, collaborating with researchers and practitioners on different projects enhances your work by providing questions and inputs from different standpoints. And finally, I’m too indecisive a person to ever be a good dam manager.

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This blog is written by Cabot Institute for the Environment member, Dr Ailish Craig, School of Geographical Sciences, University of Bristol with contributions from Dr Alan Kennedy-Asser, School of Geographical Sciences, University of Bristol and Dr Rachel James, School of Geographical Sciences, University of Bristol.

Ailish Craig
Dr Ailish Craig

Life after COVID: most people don’t want a return to normal – they want a fairer, more sustainable future

Posted on by janet.crompton
Jacob Lund/Shutterstock

We are in a crisis now – and omicron has made it harder to imagine the pandemic ending. But it will not last forever. When the COVID outbreak is over, what do we want the world to look like?

In the early stages of the pandemic – from March to July 2020 – a rapid return to normal was on everyone’s lips, reflecting the hope that the virus might be quickly brought under control. Since then, alternative slogans such as “build back better” have also become prominent, promising a brighter, more equitable, more sustainable future based on significant or even radical change.

Returning to how things were, or moving on to something new – these are very different desires. But which is it that people want? In our recent research, we aimed to find out.

Along with Keri Facer of the University of Bristol, we conducted two studies, one in the summer of 2020 and another a year later. In these, we presented participants – a representative sample of 400 people from the UK and 600 from the US – with four possible futures, sketched in the table below. We designed these based on possible outcomes of the pandemic published in early 2020 in The Atlantic and The Conversation.

We were concerned with two aspects of the future: whether it would involve a “return to normal” or a progressive move to “build back better”, and whether it would concentrate power in the hands of government or return power to individuals.

Four possible futures

Back to normal – strong government
“Collective safety”

    • We don’t want any big changes to how the world works.
    • We are happy for the government to keep its powers to keep us safe and get back on economic track.

 

 Back to normal – individual autonomy
“For freedom”

  • We don’t want any big changes to how the world works; our priority is business as usual and safety.
  • We want to take back from governments the powers they have claimed to limit our movements and monitor our data and behaviour.
Progressive – strong government
“Fairer future”

  • What we want is for governments to take strong action to deal with economic unfairness and the problem of climate change.
  • We are happy for the government to keep its powers if it protects economic fairness, health and the environment.
 Progressive – individual autonomy
“Grassroots leadership”

  • What we want is for communities, not governments, to work together to build a fair and environmentally friendly world.
  • We want to take back from governments the powers they have claimed to limit our movements and monitor our data and behaviour.

In both studies and in both countries, we found that people strongly preferred a progressive future over a return to normal. They also tended to prefer individual autonomy over strong government. On balance, across both experiments and both countries, the “grassroots leadership” proposal appeared to be most popular.

People’s political leanings affected preferences – those on the political right preferred a return to normal more than those on the left – yet intriguingly, strong opposition to a progressive future was quite limited, even among people on the right. This is encouraging because it suggests that opposition to “building back better” may be limited.

Our findings are consistent with other recent research, which suggests that even conservative voters want the environment to be at the heart of post-COVID economic reconstruction in the UK.

The misperceptions of the majority

This is what people wanted to happen – but how did they think things actually would end up? In both countries, participants felt that a return to normal was more likely than moving towards a progressive future. They also felt it was more likely that government would retain its power than return it to the people.

In other words, people thought they were unlikely to get the future they wanted. People want a progressive future but fear that they’ll get a return to normal with power vested in the government.

We also asked people to tell us what they thought others wanted. It turned out our participants thought that others wanted a return to normal much more than they actually did. This was observed in both the US and UK in both 2020 and 2021, though to varying extents.

This striking divergence between what people actually want, what they expect to get and what they think others want is what’s known as “pluralistic ignorance”.

This describes any situation where people who are in the majority think they are in the minority. Pluralistic ignorance can have problematic consequences because in the long run people often shift their attitudes towards what they perceive to be the prevailing norm. If people misperceive the norm, they may change their attitudes towards a minority opinion, rather than the minority adapting to the majority. This can be a problem if that minority opinion is a negative one – such as being opposed to vaccination, for example.

In our case, a consequence of pluralistic ignorance may be that a return to normal will become more acceptable in future, not because most people ever desired this outcome, but because they felt it was inevitable and that most others wanted it.

Two people talking on a bench
We think we know what other people think – but often we’re wrong.
dekazigzag/Shutterstock

Ultimately, this would mean that the actual preferences of the majority never find the political expression that, in a democracy, they deserve.

To counter pluralistic ignorance, we should therefore try to ensure that people know the public’s opinion. This is not merely a necessary countermeasure to pluralistic ignorance and its adverse consequences – people’s motivation also generally increases when they feel their preferences and goals are shared by others. Therefore, simply informing people that there’s a social consensus for a progressive future could be what unleashes the motivation needed to achieve it.The Conversation

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This blog is written by Caboteer Professor Stephan Lewandowsky, Chair of Cognitive Psychology, University of Bristol and Ullrich Ecker, Professor of Cognitive Psychology and Australian Research Council Future Fellow, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What is Probability?

Posted on by janet.crompton

The paradox of probability

Probability is a quantification of uncertainty. We use probability words in our everyday discourse: impossible, very unlikely, 50:50, likely, 95% certain, almost certain, certain. This suggests a shared understanding of what probability is, and yet it has proved very hard to operationalise probability in a way that is widely accepted.

Uncertainty is subjective

Uncertainty is a property of the mind, and varies between people, according to their learning and experiences, way of thinking, disposition, and mood. Were we being scrupulous we would always say “my probability” or “your probability” but never “the probability”. When we use “the”, it is sometimes justified by convention, in situations of symmetry: tossing a coin, rolling a dice, drawing cards from a pack, balls from a lottery machine. This convention is wrong, but useful — were we to inspect a coin, a dice, a pack of cards, or a lottery machine, we would discover asymmetry.

Agreement about symmetry is an example of a wider phenomenon, namely consensus. If well-informed people agree on a probability, then we might say “the probability”. Probabilities in public discourse are often of this form, for example the IPCC’s “extremely likely” (at least 95% certain) that human activities are the main cause of global warming since the 1950s. Stated probabilities can never be defended as ‘objective’, because they are not. They are defensible when they represent a consensus of well-informed people. People wanting to disparage this type of stated probability will attack the notion of consensus amongst well-informed people, often by setting absurdly high standards for what we mean by ‘consensus’, closer to ‘unanimity’.

Abstraction in mathematics

Probability is a very good example of the development of abstraction in mathematics. Early writers on probability in the 17th century based their calculations strongly on their intuition. By the 19th century mathematicians were discovering that intuition was not good guide to the further development of their subject. Into the 20th century mathematics was increasingly defined by mathematicians as ‘the manipulation of symbols according to rules’, which is the modern definition. What was surprising and gratifying is that mathematical abstraction continued (and continues) to be useful in reasoning about the world. This is known as “the unreasonable effectiveness of mathematics”.

The abstract theory of probability was finally defined by the great 20th century mathematician Andrey Kolmogorov, in 1933: the recency of this date showing how difficult this was. Kolmogorov’s definition paid no heed at all to what ‘probability’ meant; only the rules for how probabilities behaved were important. Stripped to their essentials, these rules are:

1. If A is a proposition, then Pr(A) >= 0.
2. If A is certainly true, then Pr(A) = 1.
3. If A and B are mutually exclusive (i.e. they cannot both be true), then Pr(A or B) = Pr(A) + Pr(B).

The formal definition is based on advanced mathematical concepts that you might learn in the final year of a maths degree at a top university.

‘Probability theory’ is the study of functions ‘Pr’ which have the three properties listed above. Probability theorists are under no obligations to provide a meaning for ‘Pr’. This obligation falls in particular to applied statisticians (also physicists, computer scientists, and philosophers), who would like to use probability to make useful statements about the world.

Probability and betting

There are several interpretations of probability. Out of these, one interpretation has emerged to be both subjective and generic: probability is your fair price for a bet. If A is a proposition, then Pr(A) is the amount you would pay, in £, for a bet which pays £0 if A turns out to be false, and £1 if A turns out to be true. Under this interpretation rules 1 and 2 are implied by the reasonable preference for not losing money. Rule 3 is also implied by the same preference, although the proof is arcane, compared to simple betting. The overall theorem is called the Dutch Book Theorem: if probabilities are your fair prices for bets, then your bookmaker cannot make you a sure loser if and only if your probabilities obey the three rules.

This interpretation is at once liberating and threatening. It is liberating because it avoids the difficulties of other interpretations, and emphasises what we know to be true, that uncertainty is a property of the mind, and varies from person to person. It is threatening because it does not seem very scientific — betting being rather trivial — and because it does not conform to the way that scientists often use probabilities, although it does conform quite closely to the vernacular use of probabilities. Many scientists will deny that their probability is their fair price for a bet, although they will be hard-pressed to explain what it is, if not.

Blog post by Prof. Jonathan Rougier, Professor of Statistical Science.

First blog in series here.


Second blog in series here. 

Third blog in series here.

The 95th percentile

Posted on by janet.crompton

The 95th percentile is a way of describing, in a single value, a surprisingly large outcome for any quantity which can vary.  As in ‘surprisingly large, but not astonishingly large’.

For example, heights vary across people.  Consider adult UK women, who have a mean height of about 5’4’’ with a standard deviation of about 3’’. A woman who is 5’7’’ inches would be tall, and one who is 5’9’’ would be surprisingly tall.  5’9’’ is the 95th percentile for adult UK women.  The thought experiment involves lining every adult UK woman up by height, from shortest to tallest, and walking along the line until you have passed 95% of all women, and then stopping.  The height of the woman you are standing in front of is the 95th percentile of heights for adult UK women.

The formal definition of the 95th percentile is in terms of a probability distribution.  Probabilities describe beliefs about uncertain quantities.  It is a very deep question about what they represent, which I will not get into!  I recommend Ian Hacking, ‘An introduction to probability and inductive logic’ (CUP, 2001), if you would like to know more.  If H represents the height of someone selected at random from the population of adult UK women, then H is uncertain, and the 95th percentile of H is 5’9’’.  Lest you think this is obvious and contradicts my point about probabilities being mysterious, let me point out the difficulty of defining the notion ‘selected at random’ without reference to probability, which would be tautological.

So the formal interpretation of the 95th percentile is only accessible after a philosophical discussion about what a probability distribution represents.  In many contexts the philosophy does not really matter, because the 95th percentile is not really a precise quantity, but a conventional label representing the qualitative property ‘surprisingly large, but not astonishingly large’.  If someone is insisting that only the 95th percentile will do, then they are advertising their willingness to have a long discussion about philosophy.

Blog post by Prof. Jonathan Rougier, Professor of Statistical Science.
First blog in the series here.
Second blog in series here.

Converting probabilities between time-intervals

Posted on by janet.crompton

This is the first in an irregular sequence of snippets about some of the slightly more technical aspects of uncertainty and risk assessment.  If you have a slightly more technical question, then please email me and I will try to answer it with a snippet.

Suppose that an event has a probability of 0.015 (or 1.5%) of happening at least once in the next five years. Then the probability of the event happening at least once in the next year is 0.015 / 5 = 0.003 (or 0.3%), and the probability of it happening at least once in the next 20 years is 0.015 * 4 = 0.06 (or 6%).

Here is the rule for scaling probabilities to different time intervals: if both probabilities (the original one and the new one) are no larger than 0.1 (or 10%), then simply multiply the original probability by the ratio of the new time-interval to the original time-interval, to find the new probability.

This rule is an approximation which breaks down if either of the probabilities is greater than 0.1. For example, to scale a probability of 0.04 in the next 5 years up to 20 years we cannot simply multiply by 4, because the result, 0.16 (or 16%), is larger than 0.1. In this case we have to use the proper rule, which is

p_new = 1 – (1 – p_orig)^(int_new / int_orig)

where ‘^’ reads ‘to the power of’. The example above becomes

p_new = 1 – (1 – 0.04)^(20 / 5) = 0.15 (or 15%).

So the approximation would have been 1 percentage point out in this case. The highlighted text in yellow can be pasted directly into a spreadsheet cell (the answer is 0.1507).

Of course it is unlikely to matter in practice whether the probability is 0.15 or 0.16.  But the difference gets bigger as the probabilities get bigger.  For example, it would definitely be a mistake to multiply a 0.25 one-year probability by 5 to find the five-year probability, because the result would be greater than 1.  Using the formula, the correct answer is a five-year probability of 0.76.

Blog post by Prof. Jonathan Rougier, Professor of Statistical Science.

Second blog in series here.
Third blog in series here.

Image: By Hovik Avetisyan [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

The Bristol Volcanology Group: Managing Britain’s volcanic crises

Posted on by janet.crompton

When Professor Steve Sparks moved to Bristol from Cambridge in 1989 to take up the Chair of Geology in the School of Earth Sciences little did he know what was in store for him. His time at Bristol would see him advise the government and become one of the most cited scientists of all time.

Sparks’s extraordinary journey as head of the volcanology group has lead it to study volcanism on every continent and has allowed it to grow from one man to a thriving collective of staff, researchers and students. The world-class science produced by the group has resulted in it receiving the Queen’s Anniversary Prize; the highest accolade in higher education.

 
Professor Kathy Cashman accepting the Queen’s Anniversary Prize for Higher Education

Naturally, this evolution has been heavily influenced by volcanoes.  Unlike many sciences, the progress of volcanology can be episodic- driven by key eruptions and crises. For the Bristol group, two events have defined their work which has, in turn, altered the course of the science:

The eruption on the Island of Montserrat lasted from 1995 to 1997, killed 23 people and displaced several thousand.  As Montserrat is a British dependant territory, the British government was closely engaged in managing the crisis and wasted little time roping in Bristol’s volcanic expertise as Sparks explains: “Bristol was a key partner in establishing the Volcano Observatory on the island and several Bristol staff and PhD students were involved in the monitoring effort in the first few years.” This partnership has continued for the past two decades with Professors Sparks and Aspinall acting as directors of the observatory and heading up the advisory committee ever since. In addition, the research resulting from the eruption has contributed invaluable information to the science of volcanology including causes of volcanic cyclicity and eruptions.

More recently in 2010, the Eyjafjallajokull ash crisis cost the European economy $5 billion through the closure of airspace. In the midst of the decision-making surrounding this closure was a SAGE (Scientific Advisory Group for Emergencies) meeting attended by six volcanologists, of which three were from Bristol. Bristol’s Professor Willy Aspinall, was one of the three called to advise, alongside Dr Matt Watson and Professor Sparks. He described the meeting as a ‘spectrum of people working in many areas from civil aviation to defence’.

 
Eruption column above Eyjafjallajokull

The role Bristol played was pivotal in the national response and was a turning point for the group as a whole as Watson explains ‘Eyja changed how we operated. Volcanology had previously comprised mostly of research produced for other researchers, but this was the first time we could use it practically in a crisis’.

Indeed, not only did it highlight the need for more applied approach to volcanology, it also prompted whole new field of research on volcanic ash involving analysis of ash deposits and advances in remote sensing techniques.  Such challenges were met head on by the group that has a huge breadth of research capabilities, from geophysics to geochemistry to petrology.

Looking to the future, the group’s challenge is to be prepared for new eruptions, wherever they may be.  The researchers are working in regions all over the world including countries such as Guatemala and Ethiopia. Bristol volcanologists hope to expand this aspect of their research through opportunities such as the Global Challenges Research Fund which will draw together expertise from all corners of the group to address volcanic challenges in less developed nations.

 
Keri McNamara looking at a volcanic air fall deposit in Ethiopia, alongside some of the locals 

In recent years, Sparks has stepped down as the head of the group allowing for the appointment of Professor Kathy Cashman as AXA professor of volcanology and the group’s new lead.  Now, 27 years after it began, the group is not showing any signs of slowing down. The question is, when will next episode in the group’s history erupt?

 

This blog is written by Cabot Institute member Keri McNamara, a PhD student in the School of Earth Sciences at the University of Bristol.

 

Thank you to Alison Rust, Kathy Cashman, Matt Watson, Willy Aspinall and Steve Sparks for providing information for this blog. 

Why is populism popular? A psychologist explains

Posted on by janet.crompton

This was once a referendum about whether or not the UK should remain in the EU. But not anymore. The referendum has effectively turned into a plebiscite about diversity and tolerance vs divisiveness and hatred: the Leave campaign in particular has largely ditched its long-demolished economic arguments and remoulded itself into an appeal to increasingly shrill and ugly emotion.

How could it have come to that? How could a campaign find so much popular traction by explicitly disavowing rational and informed deliberation?

Some commentators have responded to those questions with bewilderment and resignation, as if right-wing populism and hatred are unavoidable socio-political events, much like volcanic eruptions or earthquakes.

Far from it. Populism and hatred do not erupt, they are stoked. The “Tea Party” in the US was not a spontaneous eruption of “grassroots” opposition to Barack Obama but the result of long-standing efforts by libertarian “think tanks” and political operatives.

Likewise, the present demagoguery in the UK against the EU arises at least in part from media ignorance or hostility towards migrants, and a similar well-funded but nebulous network of organisations (often linked to human-caused climate change denial).

Populism is not an inevitable natural disaster but the result of political choices made by identifiable individuals who ultimately can be held accountable for those choices.

Why populism is popular

The public’s willingness to endorse right-wing populism can be explained and predicted by a range of different variables.

Has there been a financial crisis recently, for example? One particularly detailed recent analysis by a team of German economists shows that over a period of nearly 150 years, every financial crisis was followed by a ten-year surge in support for far-right populist parties. It is now eight years since the height of the last global financial crisis.

As the market goes bust, right-wing populism booms. Frank May / EPA

On average, far-right votes increased by 30% after a financial crisis, but not after “normal” recessions (that is, economic contractions that were not accompanied by a full-blown crisis). This may appear paradoxical, but it fits with other research which has shown that support for populism is not directly predicted by a person’s economic position nor life satisfaction. Instead, what matters is how people interpret their economic position: feelings of relative personal deprivation and a general view of society being in decline were found to be the major predictors of populism.

It’s not the economy, stupid, it’s how people feel.

There is now reasonably consistent evidence that populism thrives on people’s feeling of a lack of political power, a belief that the world is unfair and that they do not get what they deserve – and that the world is changing too quickly for them to retain control. Whenever people attribute the origins of their perceived vulnerability to factors outside themselves, populism is not far away.

So what about immigration?

The actual numbers of immigrants are not the sole determinant of people’s attitudes. What matters perhaps even more is how they are being interpreted. For example, in 1978, when net migration to the UK was around zero, up to 70% of the British public felt that they were in danger of “being swamped” by other cultures. Conversely, in the early 2010s, the white Britons who were least concerned about immigration were those who lived in highly diverse areas in “Cosmopolitan London”.

It’s not just immigration, it’s how people feel about their new neighbours.

London hosts lots of migrants – and few residents seem to mind. robertsharp, CC BY

Where do we go from here?

On the supply side, politicians and journalists alike must be held accountable for their choices and their words through the media, the rule of law and, ultimately, elections. London voters recently sent a clear signal about their decency when they rejected the fear-mongering of one candidate by resoundingly electing his Muslim opponent.

On the demand side, several recommendations to counter populism have been put forward, although the debate on this is still in its early stages. Two insights are promising.

First, the need to offer a vision for a better society with which people can identify. The Remain campaign has thus far focused on highlighting the risks of an EU exit. Those risks loom large but highlighting them, by itself, does not create a better world.

It would be advisable instead to focus on the many ways in which the EU has contributed to such a better world – how many UK voters remember that the EU won the Nobel Peace Prize in 2012 for transforming Europe from a continent of war to a continent of peace? How many realise that the EU is one of the few institutions able to stand up to multinational tax avoidance which appears poised to extract billions from Apple? The list goes on and deserves to be heard.

Second, we know with some degree of confidence that fear of the “other”, and hostility towards immigrants, can be overcome by interaction if certain key conditions are met. This work, mainly at the local level, is essential to heal the wounds of this divisive debate, whatever the outcome on June 23.

Lest one be pessimistic about the possibility of success, we need to remind ourselves how quickly and thoroughly we have tackled homophobia in Western societies: whereas gay people were feared, marginalised and excluded not so long ago, the UK parliament is now the “queerest legislature in the world” and has 32 MPs who call themselves gay, lesbian or bisexual.

And in Germany yesterday, 40,000 citizens took to the streets to hold hands in a gesture against racism. There is a Europe out there that should inspire rather than frighten.

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This blog is written by Cabot Institute member, Professor Stephan Lewandowsky, Chair of Cognitive Psychology, University of Bristol.  This article was originally published on The Conversation. Read the original article.

Read other blogs in the Brexit series:

University of Bristol’s Green Heroes: Martin Wiles

Posted on by janet.crompton

In the run up to the Bristol Post’s Green Capital Awards, we thought we’d highlight some of our key Green Heroes and Green Leaders at the University of Bristol.  As part of a four part blog series this week, we will be highlighting some of the key figures behind the scenes and in front of the limelight who are the green movers and shakers of our university.  There are many more Green Heroes across the University that we would like to celebrate. To find out more about who they are and what they are doing, please visit our Sustainability Stories website.
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Martin Wiles

Martin Wiles is the head of Sustainability on the University Estate Management team and leads a team of thirteen staff who have been responsible for delivering university-wide sustainability initiatives.

Martin and his team are responsible for designing and implementing green solutions to the University’s energy problems. This has lead them to an array of successes, including reducing CO2 emissions by 2000 tonnes, despite a growth in the University estate and population , through the carbon management plan. Martin and his team have accomplished this largely by the installation of carbon combined heat and power and solar photovoltaics.

Despite this achievement, Martin’s work has not been limited to CO2 reduction; the University now recycles over 80% of its domestic and construction wastes.  Additionally, he has made headway in sustainable transport solutions, procurement and construction.

As well as solving practical issues in the University’s sustainability aims, Martin has been closely engaged with the student population, through a food cooperative, cycle schemes and student conferences.

Martin attributes his green-mindedness to a geography lesson in 1980; “we were looking at de-forestation in the Amazon, couldn’t believe what was happening!”. After years of hard work to bring the university this far, his task is far from over as he elaborates; “Making the University sustainable is a long term project, the challenge is to keep everyone engaged with the agenda and taking sustainable actions, the end of 2015 Green Capital year is not the end of our sustainable work”.

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This blog is written by Cabot Institute member Keri McNamara, a PhD student in the School of Earth Sciences at the University of Bristol.

If you would like to nominate your Green Hero or Green Leader in the upcoming Bristol Post Green Capital Awards, please visit the official Green Capital Awards website.  Entries close on 18 September 2015.

To learn more about the University of Bristol’s activities  and commitments during the Bristol 2015 European Green Capital year, please visit bristol.ac.uk/green-capital.
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