climate – Page 10 – Cabot Institute for the Environment blog

Climate lessons from the past: Are we already committed to a warmer and wetter planet?

Posted on February 17, 2014April 19, 2023 by janet.crompton

Last September, the Cabot Institute and the University of Bristol hosted the 2nd International Workshop on Pliocene Climate. Following on from that, we have just released a short video describing what the Pliocene is and its relevance for understanding climate change.

The Pliocene is a geological time interval that occurred from 5.3 to 2.6 million years ago. This interval of Earth history is interesting for many reasons, but one of the most profound is that the Earth’s atmosphere apparently contained elevated concentrations of carbon dioxide – in fact, our best estimates suggest concentrations were about 300 to 400 ppm, which is much higher than concentrations of 100 years ago but lower than those of today after a century of intensive fossil fuel combustion.

Image by NASA

Consequently, the Pliocene could provide valuable insight into the type of planet we are creating via global warming. Our video release happens to coincide with pronounced flooding across the UK and focussed attention on our weather and climate. There is little doubt that increased carbon dioxide concentrations will cause global warming; instead, the key questions are: how much warming will there be and what are the consequences of that warming? One way to study that is to examine previous intervals of Earth history also characterised by high carbon dioxide concentrations. The comparisons are not perfect, of course; for example, during the Pliocene the continents were in roughly but not exactly the same positions that they are in today. But it can serve as another piece of the puzzle in predicting future climate.

One of the key lessons from Earth history is climate sensitivity. Climate sensitivity can be expressed in various ways, but in its simplest sense it is a measure of how much warmer the Earth becomes for a given doubling of atmospheric carbon dioxide concentrations. This is well known for the Pleistocene, and especially the past 800,000 years of Earth history, an interval with detailed temperature reconstructions and carbon dioxide records from ice core gas bubbles. During that time, and through multiple ice ages, climate sensitivity was about 2.5 to 3°C warming for a doubling of carbon dioxide, which is in the middle of the model-based range of predictions.

Ice core sampling.
Image by NASA ICE (Ice Core Vitals) [CC-BY-2.0]
Wikimedia Commons

Ice core records, however, extend back no more than a million years, and this time period is generally characterised by colder climates than those of today. If we want to explore climate sensitivity on a warmer planet, we must look further back into Earth history, to times such as the Pliocene. Reconstructing atmospheric carbon dioxide concentrations in the absence of ice cores is admittedly more challenging. Instead of directly measuring the concentration of carbon dioxide in gas bubbles, we must rely on indirect records – proxies. For example, carbon dioxide concentration influences the number of stomata on plant leaves, and this can be measured on ancient leaf fossils. Alternatively, there are a number of geochemical tools based on how carbon dioxide impacts the pH of seawater or how algae assimilate carbon dioxide during photosynthesis; these are recorded by the chemical composition of ancient fossils.

These estimates come with larger error bars, but they provide key insights into climate sensitivity on a warmer Earth. Recent research indicates a convergence of Pliocene carbon dioxide estimates from these various proxies and gives us more confidence in deriving climate sensitivity estimates. In particular, it appears that an increase of carbon dioxide from about 280 parts per million (the modern value before the industrial revolution) to about 400 parts per million in the Pliocene results in a 2°C warmer Earth. Accounting for other controls, this suggests a climate sensitivity of about 3°C, which confirms both the Pleistocene and model-based estimates.

It also suggests that we have yet to experience the full consequences of the greenhouse gases already added to the atmosphere.

So then, what was this much warmer world like? First of all, it was not an inhospitable planet – plants and animals thrived. This should not be a surprise; in fact, the Earth was much warmer even deeper into the past. The climate change we are inducing is a problem for humans and society, not our planet.

However, the Pliocene was a rather different world. For example – and importantly, given current events in the UK – these higher global temperatures were associated with a climate that was also wetter* than present. That provides important corroborating evidence for models that predict a warmer and wetter future.

Image by w:en:User:Ivan and licensed as GFDL

Perhaps most striking, sea level appears to have been between 10 to 40 metres higher than today, indicating that both the Greenland Ice Sheet and Antarctic Ice Sheet were markedly smaller. To put that into context, the Met Office has already commented on how flooding in the UK has been and will be exacerbated by sea level rise of 12 centimetres over the last 100 years and a further 5 to 7 centimetres by 2030.

We must be careful in how we extract climate lessons from the geological record, and that is particularly true when we consider ice sheet behaviour. One widely discussed concept is ice sheet hysteresis. This is a fancy way of saying that due to feedback mechanisms, it could be easier to build an ice sheet on Greenland or Antarctica than it is to melt one. If such hysteresis does stabilise our current ice sheets, then we should not assume a planet with 400 ppm of carbon dioxide will necessarily have sea level 20 metres higher than that of today. But if hysteresis is rather weak, then the question is not whether we will see massive sea level change but rather how long it will take (Note: It is likely to take centuries or millennia!).

Most importantly, the collective research into Earth history, including the Pliocene, reveals that Earth’s climate can change. It also reveals that climate does not just change randomly: it changes when forced in relatively well understood ways. One of these is the concentration of carbon dioxide in our atmosphere. And consequently, there is little doubt from Earth history that transforming fossil carbon into carbon dioxide – as we are doing today – will significantly impact the Earth’s climate system.

* See Brigham-Grette, J., Melles, M., Minyuk, P., Andreev, A., Tarasov, P., DeConto, R., Koenig, S., et al., 2013. Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia. Science 340 (6139), 1421-1427. doi: 10.1126/science.1233137 and Salzmann, U., Haywood, A.M., Lunt, D.J., 2009. The past is a guide to the future? Comparing Middle Pliocene vegetation with predicted biome distributions for the twenty-first century. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367 (1886), 189-204.

This blog is by Prof Rich Pancost, Director of the Cabot Institute. Rich will be giving a public lecture on how biogeochemical cycles have regulated the global climate system throughout Earth’s history on 25 February in Bristol. The event is free and open to all, do come along to learn more.

To learn more about the Pliocene – and palaeoclimate research, in general – you can watch Professor Gerald Haug’s public lecture, Climate and Societies, recorded at the Cabot Institute as part of the 2nd International Workshop on Pliocene Climate.

Prof Rich Pancost

AGU 2013: The importance of 400 ppm CO2

Posted on February 11, 2014April 19, 2023 by janet.crompton

On 1 June 2012, a concentration of 400 ppm carbon dioxide was measured in air samples in the Arctic. On 9 May 2013, Mauna Loa, the longest recording station, measured a daily average of 400 ppm carbon dioxide. Next year we may see the global average concentration reach 400 ppm and the year after that 400 ppm could be measured at the South Pole. The 400 ppm number is arbitrary, but it is a symbol of the anthropogenic climate change that scientists have been talking about for many years.

Here at the University of Bristol, the upcoming 400 ppm epoch prompted the question of what do we know about 400 ppm CO2 climates and how could it be used to galvanize action on climate change? But 400 ppm and climate change is a bigger issue than one University can take on, so we took our idea to the American Geosciences Union Fall conference. With more than 24,000 attendees each year, AGU is the perfect place to talk about what 400 ppm CO2 means in a scientific sense and what we as scientists should do about communicating it.

Two sessions were proposed: one looking at the science of 400 ppm CO2 climates, co-convened with Kerim Nisanciouglu of the University of Bergen, Norway, the other at communicating 400 ppm co-convened with Kent Peacock of University of Lethbridge and Casey Brown of UMass Amherst.

Naomi Oreskes (pictured) asked why scientists
don’t allow themselves to sound alarmed when reporting alarming conclusions from their
research.

The communication session looked at how climate science could be communicated effectively. First to speak was Naomi Oreskes, who asked why scientists don’t allow ourselves to sound alarmed when we’re reporting alarming conclusions. Citing from neuroscience research, Oreskes argued that when scientists conform to the ‘unemotional scientist’ paradigm they actually risk being less rational and sounding inauthentic. It was clear that Oreskes’ points struck the audience, as many of them queued up to ask questions.

Myles Allen made a compelling case for sequestered adequate fraction of extracted (SAFE) carbon – i.e. compulsory carbon capture and storage. Allen pointed out that people will always pay to burn carbon and argued that a carbon price is just a way to ‘cook the planet slower’. Robert Lempert took a less controversial stand and explained how uncertainty can be managed in robust decision making. Using hydrological examples, Lempert suggested that by starting with the desired outcome and working backwards, uncertainty can be dealt with. The session finished with James Hansen, talking about the right message, and how the things that people care about needs to be communicated by the best communicators. Criticising the pursuit of unconventional fossil fuels, Hansen argued the need for a carbon tax which was redistributed back to people. A lively question and answer session followed, with all the speakers engaging in a strong discussion and the audience contributing pointed questions. No problems with talking without emotion in this session!

The 400 ppm physical science session started by focussing on what information we could draw from climates in the past where CO2 is believed to have been ~400 ppm. The first speaker was Alan Haywood who summarised the work of the PlioMIP project which tries to understand the climate of the Pliocene (~3 million years ago) – what it was like and why. The Pliocene is the most recent time period in the past when atmospheric CO2 concentrations could have been as high as they are today. Two more Pliocene presentations followed. First, Natalie Burls (standing in for Chris Brierley) explained that even with CO2 set to 400 ppm in their climate model simulations they could not match the warm temperatures reconstructed by Pliocene data – suggesting that either the climate models are not sensitive enough to CO2 or that there are other dynamical processes that we do not fully understand yet. Thomas Chalk gave a comparison between different methods for reconstructing CO2 in the past, and concluded that the Pliocene concentration was indeed at around 400 ppm. The final talk in the palaeoclimate part of the session was given by Dana Royer who presented the most compelling evidence for very different climates in the past with polar forests at 80°N indicating annual mean temperatures in the Arctic that were 30°C warmer than they are today! Dana presented new CO2 reconstructions demonstrating that the CO2 concentration at the time of the polar forests could have been around 400 ppm, again suggesting that our climate models may not be sensitive enough to CO2.

The next part of the session looked at current CO2 levels with a presentation by Steven Davis about the amount of CO2 that we have already committed to putting into the atmosphere. The energy infrastructure that we have already built amounts to future CO2 emissions of 318Gt, and new global commitments are still increasing. Vaughan Pratt followed with a talk about the reasons for the recent pause in the global warming trend, separating out natural causes and anthropogenic causes using mathematical and statistical analyses. He concludes that the recent pause is of natural origin.

The final part of the session peered through the looking glass into the future. Andrew Friedman investigates the causes of the temperature asymmetry between the northern hemisphere and the southern hemisphere and how that asymmetry may alter under the future climate emission scenarios. He concluded that the asymmetry is set to increase into the next century, with the northern hemisphere warming faster than the southern hemisphere and projects that the tropical rainbelt will shift northwards as a result.

Kirsten Zickfield has found that warming in the next
millenium might amount to 1 degree globally,
concentrated at the Poles. Sea levels are projected to
rise by 0.8m.

The final talk of the session was given by Kirsten Zickfeld who examined the climate changes we might already be committed to as a result of the CO2 emissions we have already released (under the assumption that atmospheric CO2 stays at 400 ppm). She used a climate model with biogeochemical components to identify how long it would take for the climate to reach equilibrium with the present CO2 concentration of 400 ppm, what the climatic impacts of that equilibrium might be and whether it might be possible to return to CO2 levels below 400 ppm on human timescales by using negative emissions (carbon capture/storage schemes). She found that the already committed warming into the next millennium might amount to 1°C globally, concentrated at the poles. Sea levels are projected to rise by 0.8m due to thermal expansion alone and further increases of 10m due to ice melt are possible over much longer timescales. Committed changes for the ‘other CO2 problem’ – ocean acidification – are relatively small, with a pH drop of only 0.01 projected. She concludes that even if CO2 levels could drop below 400 ppm in the future, whilst air temperatures may stabilise, sea level may continue to rise due to thermal expansion alone.

Both of the sessions were recorded for access after the event and provoked a lot of debate, during the sessions and online. We hope that in some small way these sessions have helped scientists think differently about what 400 ppm means and what we can do about it.

This blog was written by T Davies-Barnard and Catherine Bradshaw, Geographical Sciences, University of Bristol.

The carbon mountain: Dealing with the EU allowance surplus

Posted on January 31, 2014April 19, 2023 by janet.crompton

It’s not news that the EU emissions trading system (EU-ETS) is in trouble. A build-up of surplus emission allowances has caused dangerous instability in the carbon market and a plunge in prices since the economic slump in 2008 began (See Figure 1, courtesy of David Hone).

Figure 1, courtesy of David Hone

The discussion at the All Party Parliamentary Climate Change Group’s (APPCCG) meeting on the 28th of January centred on the causes and consequences of the EU-ETS allowance surplus. The majority of speakers at this session had a background in the discipline of economics, so inevitably the exchange of views was… frank. The panel were in agreement that EU-ETS is in crisis; but can and should it be saved?

Emissions trading schemes, of which EU-ETS is a canonical example, are an attempt to allow market forces to correct the so-called ‘market failure’ that is carbon emission. From the point of view of a classical economist, the participants in carbon emitting industries do not naturally feel the negative effects their activities cause to the environment. Emissions trading forces carbon emitters to ‘purchase’ the right to pollute on a market. In effect, they pay to receive permits (or allowances) to emit a certain level of emissions. If they do not reach this level of emission, the excess can be sold back onto the market, allowing others to make use of it. The prices of permits are determined by market forces, so cannot be fixed by the EU. The quantity of permits is within the control of the EU, and this is where the problem lies.

In the aftermath of the 2008 slump, a surplus of allowances began to build up, leading to a crash in the price of allowances. Many commentators blame EU economic forecasting for this problem, as the recession and consequent reduction in economic activity was not factored in to the EU-ETS control mechanism. Criticism has been forthcoming for the economic models used, and some go as far as to liken the mismanagement of EU-ETS to the ‘wine-lake and butter-mountain’ days of the 1980s, where the Common Agricultural policy was allowed to consume over 70% of the EU’s budget. Perhaps the models are too simple – James Cameron, a speaker at the APPCCG event, spoke of the ‘premium on simplicity’ that exists in creating policy. Maybe that approach has extended itself into the mathematical models used to predict the performance of EU-ETS, rendering them over-simplistic?

Personally, I see things a little differently. It’s clear that economic models are often far from perfect; however, I’m not sure that’s where the problem lies. In the implementation of policy, decision makers have to draw on the implications of many separate models; for instance, they must consider the GDP growth of EU member states, their adoption rate of new energy efficiency standards and the relative industrialisation of their economies. To my mind, the greatest source of error is in the gaps and interfaces between these economic models. Policy makers must make decisions on how to interpret the way economic predictions will interact with one another, and these interpretations are always subject to value judgements. What we need is a more joined-up approach.

Climate science has long used ‘macro-models’ to incorporate a variety of physical processes into their predictions, an approach that could be adopted by economists as well. While the first economic macro-models may not achieve even a fraction of the accuracy of climate models, that is not to say they cannot be improved through collaboration and quantitative criticism. Perhaps now is the time to make a start?

This blog is written by Neeraj Oak, Cabot Institute.

Neeraj Oak

Environmental uncertainty: A challenge to both business and vulnerable communities

Posted on December 11, 2013April 19, 2023 by janet.crompton

In September, the IPCC published the Fifth Annual Report on the Physical Basis of Climate Change. It devotes little attention to the human and ecological impacts of global environmental and climatic change, topics that will be addressed by working group reports released in early 2014 . Nonetheless, the trajectory of climate and other environmental changes and their implicit impacts on society are stark. Despite numerous treaties and efforts at mitigation, concentrations of carbon dioxide and other greenhouse gases continue to increase, and at greater rather than diminished rates. If those rates continue they will result in global warming of 3 to 5.5°C by 2100. This in turn, will result in dramatic changes to the global hydrological cycle, including both more evaporation and more rainfall.

A More Uncertain Climate

Flood by Paul Bates

The results will be a more hostile climate for many as land can become either drier or more flood-prone or both, changes exacerbated in coastal areas by sea level rise. Freshwater supply will also be affected by the forecast changes in climate. The quantity of water flowing in glacier or snow-melt fed river basins will change, affecting around a sixth of the world’s population[i], while coastal freshwater will be contaminated with saline water[ii]. Areas of the Mediterranean[iii], Western USA[iv], Southern Africa[v] and North Western Brazil[vi] are projected to face decreased availability of freshwater.

Key to understanding who will be affected is our ability to predict changes in rainfall, seasonality, and temperature at a regional scale. However, regional climatic predictions are the most challenging and least certain, especially with respect to the nature and amount of rainfall. For vast parts of the world, including much of South America, Africa and SE Asia, it is unclear whether climate change will bring about wetter or drier conditions. Thus, uncertainty will become the norm: uncertainty in rainfall; uncertainty in weather extremes and seasonality; and most importantly, uncertainty in water resources.

Those combined effects lead to an additional and perhaps the most profound uncertainty for the latter half of the 21st century: uncertainty in food production and access. In the absence of other factors, climate uncertainty and more common extreme events will compromise agriculture at all scales, yielding increased food prices and increased volatility in markets.

Impacts on the Poor

Although the human impacts of climate change will be diverse, their effects will be worst for the most impoverished and, by extension, least resilient population groups. The UN reports that climate change could “increase global malnutrition by up to 25% by 2080.” And all of this occurs against a backdrop in which access to food is already a challenge for the poorest of the world already a challenge for the poorest of the world [p5], a situation exacerbated by the global financial crash.

These risks to the poorest result from a lack of resources to mitigate harm, lack of power to protect resources, and the global competition for resources.

Those who lack the financial resources to migrate or build more hazard-resistant homes will suffer most from extreme events, as has been sharply illustrated by those suffering most in the aftermath of Typhoon Haiyan. Those who can least afford to dig deeper wells into more ancient aquifers as water resources diminish will go thirsty. Subsistence farmers – and those dependent on them – are less resistant to climate shocks (desertification) and adverse weather events (flooding) than commercial farmers.

Land ownership for the poorest is often tenuous, and displacement from land a serious problem for many. Previous switches to biofuels have led to land competition, resulting in both loss of land to subsistence [p6] farmers, and diversion of commercial production leading to shortages [p7] and increased food prices. Within communities, these effects are not evenly spread as marginalised groups, such as women, are the least likely to hold land tenure [p8] . Similarly, there is increased competition for water [p9] between peoples, but also between water for industry (including agriculture) and water for drinking. When water is scarce, pollution of fresh water is common, and governance is weak, the poorest are likely to lose out.

Image by Mammal Research UnitUniversity of Bristol

Food competition will most likely be exacerbated by other factors: rising demand from a rapidly expanding population and a growing demand for meat from a global ‘middle class’; the increased economic divide between post-industrial and developing nations; the ongoing depletion of soil nutrients and associated impacts on the nutritional value of our food. The combination of these factors will result in profound impacts on food security. Who decides what gets grown? Who can afford it in the context of global markets and the loss of agricultural land? The poorest members of even the wealthiest societies are the most vulnerable to dramatic and unpredictable changes in food costs[p10] .

‘Wicked Problems’

These issues yield a profoundly challenging ethical issue: the wealthy who are most responsible for anthropogenic climate change, via the greatest material consumption and energy demand, have the greatest resilience to food market fluctuations and the greatest means for avoiding their most deleterious impacts. Therefore, these issues challenge all governments to dramatically and swiftly act to decrease greenhouse gas emissions and mitigate the associated climate change.

Unfortunately, many proposed mitigation strategies could also have negative consequences for food prices and availability. Increasing energy prices, such as those brought about by a carbon tax, will be passed onto food prices. Genetically modified foods could be essential to feeding a growing population, and we would urge that future efforts expand to incorporate a greater degree of climate resilience in crops; however, the patents on those crops can make them financially inaccessible to the poorest nations or build critical dependencies.

Although sustainable agriculture and crops might reduce the impact of climate change and uncertainty in some countries, these solutions can be deleterious for the poorest. They are more likely to live in regions and areas most negatively affected by climate change, most likely to be relying on subsistence/small scale agriculture and least likely to have access to the global market as consumers. In other words, a stable global market will be of little direct benefit to them; in fact, most of these populations are likely to face competition for land/water use from globalised markets (for biofuels or commercial farming). In short, what builds food resilience in one nation might be exposing the most economically vulnerable in another.

In fact, when properly mobilised for the benefit of the community, access to new energy sources – even if in the form of fossil fuels – can be transformative and facilitate the economic growth needed to access increasingly globalised food markets [p12]. Domestic access to gas reduces the need to collect wood for fires, reducing deforestation, improving air quality, and freeing up time for communities to address other development needs.

This is not an argument against mitigation of climate change, but it does need to be balanced against human development needs; and this represents one of the world’s most profound challenges. In some circles, we consider this a ‘wicked’ problem: a problem that has multiple causes, probably in interaction, and where information is incomplete, such that proposed solutions might be incomplete, contradictory, complex and work across multiple causes in complex systems.

Challenges and Opportunities

Biofuel by La Jolla

Wicked problems are not intractable, however, and previous studies of land use for biofuels provide clues as to how a complex solution could be more sustainable for all; well planned switches to biofuels which consider local custom in land tenure can provide more land for agriculture, and reduce deforestation pressure.

In such situations, we argue, solutions which focus on halting or slowing climate change alone, and then coping with the business and development problems that they might create answer the wrong question. Our challenge to the business (and academic) community, then, is to engage with some wicked questions:

What are the business opportunities in improving the social and physical environment?
Can the global agricultural system be a single resilient network, rather than a competition?
What technology or innovation is needed to support a resilient food network?
How can innovative solutions to these challenges generate local income, allowing reinvestment in education and development?

These are difficult questions but they also represent opportunities for development and growth in poor communities. A world with increasing environmental uncertainty is a challenge for both businesses and vulnerable communities. But it could also be a shared opportunity for growth and development: to innovate and identify new solutions, to co-invest in local resilience and risk reduction, and to share the growth that arises from more stable communities.

[i] Z Kundzewicz, L Mata, N Arnell, P Doll, P Kabat, K Jimenez, K Miller, T Oki, Z Sen & I Shiklomanov, Freshwater Resources and their Manegemtn. Climate Change 2007: Impacts, Adaption and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, 2007
[ii] R Buddemeier, S Smith, S Swaaney & C Crossland, The Role of the Coastal Ocean in the Disturbed and Undisturbed Nutrient and Carbon Cycles, LOICZ Reports and Studies Series, 2002, 84
[iii] P Etchevers, C Golaz, F Habets & J Noilhan, Impact of a Climate Change on the Rhone River Catchment Hydrology,Journal of Geophysical Research, 2002, 4293
[iv] J Kim, T Kim, R Arritt & N Miller, Impacts of Increased CO2 on the Hydroclimate of the Western United States, Journal of Climate, 2002, 1926
[v] M Hulme, R Doherty & T Ngara, African Climate Change, Climate Research, 2001, 145
[vi] J Christensen, B Hewitson, A Busuioc, A Chen, X Gao, I Held, R Jones, R Kolli, W Kwon, R Laprise, V Magana Rueda, L Mearns, C Menendez, J Raisanen, A Rinke, A Sarr & P Whetton, Regional Climate Change, The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change,2007, 847

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This blog is written by Prof Rich Pancost, Director of the Cabot Institute and Dr Patricia Lucas, School for Policy Studies, both at University of Bristol.

Prof Rich Pancost

This blog has kindly been reproduced from the Business Fights Poverty blog.

Nine lessons and carols in communicating climate uncertainty

Posted on December 6, 2013April 19, 2023 by janet.crompton

About a month ago I was invited to represent the Cabot Institute at the All Parliamentary Party Climate Change Group (APPCCG) meeting on “Communicating Risk and Uncertainty around Climate Change”. All Party Groups are groups of MPs and Lords with a common interest they wish to discuss, who meet regularly but fairly informally. Here are the APPCCG register, blog, Twitter and list of events.

The speakers were James Painter (University of Oxford), Chris Rapley (UCL) and Fiona Harvey (The Guardian), and the chair was (Lord) Julian Hunt (UCL). Rather than write up my meeting notes, I’ll focus on the key points.

[Disclaimer: All quotes and attributions are based on my recollections and note-taking, and may not be exact.]

1. People have a finite pool of worry

I’ll start with this useful phrase, mentioned (I think by Chris) in the discussion. Elke Weber describes this:

“As worry increases about one type of risk, concern about other risks has been shown to go down, as if people had only so much capacity for worry or a finite pool of worry. Increased concern about global warming may result in decreased concern about other risks…the recent financial crisis reduced concern about climate change and environmental degradation.” — “What shapes perceptions of climate change?”; pdf currently here)

Lessons: We cannot expect or ask people to worry about everything: concern about other issues can reduce concern about climate change, while evoking strong emotions about climate change can reduce concern about other issues. So Chris encouraged talking about opportunities, rather than threats, wherever possible.

2. People interpret uncertainty as ignorance
People often interpret the word “uncertainty” as complete ignorance, rather than, for example, partial ignorance(..!) or a well-defined range of possible outcomes. This may be due to language: “I’m not certain” is close to “I don’t know”.

Just as important is exposure to research science. Science is often presented as a book of facts, when in fact it is a messy process of reducing our uncertainty about the world. At a school this year the head teacher told us about an Ofsted inspection during which they had a fantastic science workshop, where groups of students solved challenging problems using real data. At the end of the day, the inspector said: “Fine, but wouldn’t it have been quicker to have told them the answer first?”

Lessons: Revolutionise the education system.

3. People are uncomfortable with uncertainty

Even when people do understand uncertainty, it can become a convenient rug under which to brush difficult decisions. Chris said that over-emphasising uncertainty leads to decision-making paralysis. When a decision invokes fear or anxiety (or, I would add, political disagreement), uncertainty can be used to dismiss the decision entirely.

“The Higgs boson”, Chris said, “was not a ball bearing found down the back of sofa, but a statistical result”. It was just possible it hadn’t been discovered. But it wasn’t reported this way. The Higgs, of course, does not invoke fear, anxiety or political disagreement (though please leave comments below if you disagree).

Lessons: Decision paralysis might be reduced by talking in terms of confidence rather than uncertainty. But perhaps more importantly…

4. People do accept the existence of risk

Finite worry and the problems of talking about uncertainty need not mean deadlock, James and Chris argued, because people do understand the concept of risk. They accept there are irreducible uncertainties when making decisions. Businesses are particularly familiar with risk, of course. James mentioned that Harvard Business School is actively viewing climate change in this way:

“It’s striking that anyone frames this question in terms of ‘belief,’ saying things like, ‘I don’t believe in climate change,’… I think it’s better seen as a classic managerial question about decision-making under uncertainty.” — Forest L. Reinhardt, Business and Environment Institute faculty co-chair, HBS

Viewed in this way, the problem is not whether to make a decision based on uncertain or incomplete information, which is nearly always the case in other spheres (Chris: “Why should climate change be a special case required to have absolute certainty?”). The problem is whether the decision made is to bet against mainstream climate science:

“It seems clear that no one can know exactly what’s going to happen–the climate is a hugely complex system, and there’s a lot going on”….[The vast majority of the world’s scientists] may be wrong. But it seems to me foolish to bet that they are certainly wrong.“ — Rebecca Henderson, Business and Environment Institute faculty co-chair, HBS

Chris pointed out that the Technical Summary of the latest Intergovernmental Panel on Climate Change (IPCC) assessment of climate science uses the word “uncertainty” a thousand times and the word “risk” not at all, so it is not surprising the media focus on uncertainty. And how well humans understand risk is a matter worthy of much discussion. But as James writes:

“There is… a growing body of literature suggesting that risk language may be a good, or at least a less bad, way of communicating climate change to the general public”. — “Climate Change in the Media: Reporting Risk and Uncertainty”, (Executive Summary, page viii)

Lessons: Where possible, talk in terms of risk not uncertainty; see for example the IPCC report on extreme weather and, naturally, our book Risk and Uncertainty Assessment for Natural Hazards.

5. Scientists have little training

Most of us are not well trained – perhaps hardly at all – in science communication. But we must consider how the way we present numbers affects their interpretation. In 2007, the IPCC said the likelihood that most of global warming since the mid-20th century was caused by greenhouse gas emissions was assessed to be greater than 90%. This year they made a similar statement but the likelihood was 95% or greater. Chris said that if a journalist asked, “What does it mean to increase from 90% confident to 95% confident?”, a scientist could make this clearer with “[We think] the chance climate change is natural is now half as likely as before.”

He also pointed out that we don’t have training in how to deal with the “street fight” of the climate debate. In my experience, this is one of the two main reasons why most of my colleagues do not do public engagement (the other being time commitment).

Lessons: For communicating uncertainty and risk, I recommend UnderstandingUncertainty.org. For dealing with the street fight, my advice is first to start with a lot of listening, not talking, to get a feel for the landscape. And to talk to climate scientists already engaging on how to avoid and deal with conflict (if, indeed, they are avoiding or dealing with conflict…).

6. Journalists have little (statistical) training
The IPCC assessment reports use a “language” of uncertainty, where phrases such as “extremely likely” are given a specific meaning (in this case, 95% or greater likelihood). But James said that only 15% of media articles about this year’s report explained the meaning of this uncertainty language.

And in the discussion someone quoted a journalist as saying “The IPCC report says it has 95% confidence – what do the other 5% of the scientists think?” In other words, confusing the idea of a consensus and a confidence interval. There was a laugh at this in the room. But I think this is easily done by people who do not spend all day thinking about statistics. That would be: the majority of the human race.

Lessons: Er, many journalists could benefit from more statistical training. Here is what that might look like.

7. “Newspaper editors are extremely shallow, generally”
Fiona, her tongue only slightly in cheek, gave us this memorably-made and disappointing (if predictable) point.

Just because something is important it doesn’t mean it will get into a news outlet. An editor might go to a cocktail party, talk to their glamorous celebrity friends, hear some current opinion, and then the next day their paper says…

In other words, the social diary – including meetings with high profile climate sceptics – can have a substantial influence on the viewpoint taken. (Of course, she noted, the editor of The Guardian is a profound man, not influenced by such superficiality). To counter this we would need to go to influential people and whisper in their ears too. We would need to launch a prawn cocktail offensive – or more appropriately, as one wit suggested, a goats cheese offensive. You heard it here first. And last.

Lessons: Go to more cocktail parties hosted by influential people.

8. There are many types of climate sceptic
There was generally support of scepticism by the speakers. Chris said it was perfectly valid for the public to ask scientists “Can we see your working?”; in other words, to ask for more details, code and data. All the speakers said they don’t use the word “denier”.

James said we should not generalise, and described four types of sceptic: trend, attribution, impacts, and policy. A trend sceptic would not be convinced there is global warming; an attribution sceptic about how much is man-made; an impacts sceptic might say we don’t know enough about when and how severe the impacts will be; and a policy sceptic would take issue with how to tackle the problem. (Personally, I believe there are as many types of sceptic as there are sceptics, but that would be a longer list to write down). Fiona pointed out that one person can be all these types of sceptic, moving from one argument to another as a discussion progresses. Some thought this would be incoherent (i.e. kettle logic, contradictory arguments) but others thought it could be coherent to be sceptical for more than one of those reasons.

Lessons: Treat each sceptic as an individual (flower); don’t assume they are one type of sceptic when they may be another, or more than one.

9. Trust is important

What determines people’s views on climate change? As James pointed out, there is evidence that what drives opinions is not science, or even the media (they determine only the topics of discussion), but political, cultural and social values. Fiona had said earlier in the meeting, “Climate change is more politicised than ever before in my lifetime: it is becoming a matter of right or left. This is very, very scary. If you allow this, you lose any hope of doing anything sensible about it.”

All this is true. But I’ll end with a slightly more optimistic quote, which I think was from Chris: “The sea change in the battle with tobacco companies was when the message got across that the adverts were not trustworthy.” I quote this not because I believe it is the same as the climate debate, and not because sceptics are untrustworthy (though some may be), but because I (some might say, choose to) interpret it to mean that trust is important. When people trust the messenger, the message is more likely believed.

Lessons: Other things are important, but sometimes communication is a matter of trust. I emphasise this point because it’s what I already believe; others may disagree (politely, please…).

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I would have liked to add more references supporting the points made by the speakers, but ran out of time. Some are in James’ book mentioned above. Do please add them in the comments if you have them.

The title of this blogpost came from realising I had nine points to make and thinking of this set of shows curated by Robin Ince celebrating science, skepticism, and rationalism. If you’re in the UK this December, do go.

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This blog is written by Dr Tamsin Edwards, Geographical Sciences, University of Bristol and also features on her PLOS blog All Models Are Wrong.

Follow Tamsin on Twitter @flimsin