In 2004, science historian Naomi Oreskes published a seminal essay in the journal Science entitled The Scientific Consensus on Climate Change.[i] In it, Oreskes reported the results of a survey of 928 abstracts published in refereed scientific journals between 1993 and 2003. Of those abstracts, 75% supported the prevailing view among the scientific community that most of the observed warming of the earth’s atmosphere was due to an increase in greenhouse gas concentrations arising from human activities. Importantly, the remaining 25% of the abstracts did not disagree with that consensus position, but rather put no position at all. Stunningly, none of the abstracts disagreed with the consensus position.
Fast forward eight years and the Australian Broadcasting Corporation aired I Can Change Your Mind About Climate, a documentary which followed climate change activist Anna Rose and retired Liberal Senator Nick Minchin as they visited a number of international figures with differing views about anthropogenic (or human-induced) climate change.[ii] The basic premise of the documentary was that the science behind climate change is, if not contested, then at least contestable. In other words, Oreskes’ reported consensus had apparently evaporated in just eight years.
I Can Change Your Mind About Climate is interesting in that it highlights a number of dissenting views, but is limited in that it gives equal air time to views which, in the wider scientific community, are not represented in anywhere near equal proportions. How can non-scientists navigate a policy discussion populated with seemingly irreconcilable scientific views? In order to address this question we must have some understanding of how science functions, how scientific knowledge evolves and how we can elicit truth from scientific data.
The basic purpose of science is to explain the workings of the universe. In this respect, science is fundamentally descriptive: that is, scientific endeavour seeks to examine and explain the natural processes which govern the world using careful observation and measurement. In establishing these workings, a second aspect of scientific endeavour also becomes available: science can often predict the outcome of particular processes, based on previous measurements and observations of the same or similar processes. In short, science provides us with both explanations and predictions about the natural world.
Importantly, the specifics of scientific endeavour vary from discipline to discipline. For instance, in botany observation is of paramount importance and thorough statistical analysis of observations will be necessary in order to properly interpret data. Situations deviating from the expected result will occur. On the other hand, disciplines like chemistry tend to operate with a great degree of predictability, with experiments adhering closely to predicted theoretical scenarios. In some cases there is effectively 100% certainty that a particular experiment will give a particular outcome.
Consider, as an example, two particular experiments using lead nitrate. In the first case, a solution of lead nitrate is mixed with a solution of sodium iodide. In the second case, a solution of lead nitrate is administered to a laboratory rat. In the first case, mixing lead nitrate and sodium iodide gives a bright yellow precipitate of lead iodide. This is a popular science class experiment partly because of the attractive yellow product, but also because of the certainty with which the reaction occurs. Short of using the wrong chemicals, the result is more or less assured.
However, in the case of administering a lead nitrate solution to a rat, the outcome of the experiment is less certain. If a dose of 70 mg/kg bodyweight of lead nitrate is administered to a particular rat, that rat may or may not die. In fact, toxicologists have established that this dose sufficient to kill 50% of a population of rats.[iii] There is an obvious, inbuilt variability with this measure: you might administer the same dose to two individual rats and have one die and the other survive. This is not to say that the result is worthless, or that the science is bogus. Indeed, the figure has been determined by performing many experiments, the results of which have been analysed statistically to calculate the computed value. However, the result needs to be used in an informed way for its worth to be appreciated.
What makes these two situations different? Both have been evaluated scientifically, and numbers can be computed in both situations.[iv] Moreover, in both situations one can make predictions about future experiments from the results obtained. However, the accuracy of the prediction made is different in the two situations: one is near certainty, the other, fifty-fifty. The reason for this difference in the accuracy of the prediction relates to the complexity of the two systems. Adding lead nitrate solution to sodium iodide solution gives a highly reproducible outcome, essentially because the experiment involves very pure materials. The potential for side reactions and unexpected results is thereby minimal. However, where lead nitrate is administered to a living specimen there is far greater potential for confounding factors.[v] Toxicologists are not lesser scientists than chemists, but they operate with more complex systems and as a result the certainty with which their predictions come to pass is different.
In seeking to explain particular systems, scientists propose models and theories intended to make sense of the collected data. For example, toxicologists have proposed various theories about the mechanisms by which lead is toxic to rats. Careful experimentation is required to determine the specifics of these mechanisms, and theories will vary with time as new information comes to light. In complex systems like biological organisms, our understanding can evolve quickly as new and better theories are proposed and old explanations are eclipsed. In certain cases there may be two possible theories to explain the one observation. In such a case, further experimentation or observation is required in order to effectively distinguish between the two theories.
Moreover, any scientific theory will be underpinned by assumptions which may or may not be valid. In chemistry and physics, the assumptions tend to be well-established and to hold in the majority of situations. However, the more complicated a system becomes, the greater the number of assumptions that will underpin any particular piece of scientific interpretation. Further, the greater the number of assumptions the more likely that one or more of these assumptions might ultimately prove to be faulty. This does not make the study of a complex system ‘less scientific’ than the study of a simple system. It does, however, mean that scientific information about complex situations needs to be appropriately handled, with proper estimations of error and acknowledgement of the assumptions that underpin any predictions made.
Consequently, evaluating a truth claim in science requires a basic level of scientific literacy. Truth claims, when made by scientists should come with appropriate caveats; there is always a finite possibility that any scientific statement might ultimately be proven wrong. Most scientists appreciate this, and predictions are usually made with estimations of the associated uncertainty. When a scientist adds lead nitrate to sodium iodide, they can be bold in their prediction of the outcome – the assumptions are well understood, the measurement is straightforward and the model is tried and true. When dealing with a living organism things become more complicated – the assumptions multiply, the measurement is more complicated, the model is more dynamic and the outcome less certain. So in something as complex as the world climate, how confident can we be in the explanations and predictions which science provides?
The discipline of climate science is not so much a discipline in its own right as it is a suite of branches of science. Included among the 800 or so proposed authors of the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) are oceanographers, geochemists, geophysicists, atmospheric scientists, meteorologists, geographers, and mathematicians. Attempts to characterize climate science as new and untested cannot be reconciled with the fact that these disciplines have existed in their own right for decades, and in some cases, centuries.
Equally important is the variety of methodologies which are being applied in climate science. For instance, some researchers are conducting direct measurements of the historical carbon dioxide concentration by extracting ice cores from the arctic and Antarctic regions.[vi] Others are seeking to determine carbon dioxide levels in history by examining botanical[vii] or zoological[viii] evidence. These investigations use the tools of chemistry, physics, botany and zoology to make estimations of carbon dioxide levels. They are not overly dependent on complex mathematical models: they are measured quantities which can be known with a fair degree of certainty. These results give a clear indication of the historical trend in atmospheric greenhouse gas levels.
Other climate scientists are concerned with developing numerical models to predict the trajectory of global surface temperatures should the level of greenhouse gas in the atmosphere continue to rise. These scientists are generally mathematicians, or climatologists with a high level of mathematical training. Undoubtedly, modelling a system as complicated as the global temperature is an ambitious exercise, and therefore the models are constantly being refined and improved. These models are not capable of predicting the temperature in any given year, nor are they intended to: they are designed to deal in long term averages. Moreover, each model incorporates a degree of uncertainty. Even so, using these models climate scientists have been able to model the current trend in global surface temperature and sea level. The results suggest that if global greenhouse gas emissions had remained steady then the increase in temperature and sea level would not have occurred to the extent that it has. As noted above the models incorporate a level of uncertainty, but even taking that uncertainty into account the IPCC considers it ‘highly likely’ that human emissions are contributing to global climate change. The language of likelihood is chosen not to obscure, but to accurately reflect the complexity of the situation.
It is important to note that climate scientists are not attempting to hide the uncertainty associated with their studies: rather, I would contend that the global climate science community has been more open about the potential error in their results than most other scholarly communities. The Synthesis Report associated with 4th Assessment Report of the IPCC begins with a discussion about uncertainty, and cites the IPCC’s Uncertainty Guidance Note.
The IPCC uncertainty guidance note defines a framework for the treatment of uncertainties across all WGs (Working Groups) and in this Synthesis Report. This framework is broad because the WGs assess material from different disciplines and cover a diversity of approaches to the treatment of uncertainty drawn from the literature.[ix] [emphasis mine]
The IPCC clearly acknowledges that there is a degree of discipline-dependent uncertainty in climate science. This is not some simple case of mixing two chemicals together and observing the outcome. It is also far more complex than administering a chemical to a population of rats. Studying the world climate is a profoundly complicated exercise requiring sophisticated mathematical and statistical models. As such, the obtained results will have an associated uncertainty, the result of which is that any prediction (e.g., sea level rise, average temperature rise) is usually presented as a range of possible values. The existence of scientific uncertainty is not grounds for disregarding the information provided, but rather assists in properly interpreting and using the science.
When public policy is developed to address scientific problems it is inevitable that non-scientists (politicians, public servants, journalists, lobbyists, commentators, and the public) will need to use scientific information. Further, as the issues involved become more complex, and the scientific methods more elaborate, the potential for mistake or misrepresentation becomes substantial. Part of the difficulty is that in the public discussion ideas are often presented in definitive terms; nuance tends to be absent. So when scientists speak of ‘likelihood’ and ‘uncertainty’, the words can be construed as the weasel words of a politician, not as the language of a careful scientist. The result is that in the public discourse scientists can be forced into definitive language which, in some cases, is not warranted by the studies under discussion. We arrive in a situation where scientists are unable to relay an accurate representation of their work: using careful, appropriate language raises a disproportionate level of doubt, while using more definitive language implies a certainty of prediction that does not exist.
One example where the language of the scientific community was not appreciated by a non-specialist audience was the 2009 ‘Climategate’ scandal, which arose from the hacking of servers at the University of East Anglia’s Climate Research Unit. Members of the media and some politicians made much of the reference in one disclosed email, authored by Prof. Phil Jones, to a scientific ‘trick’:
I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) [and] from 1961 for Keith’s to hide the decline.
Taken out of context, the excerpt looks suspicious. However, with the necessary context the quote loses its scandalous edge. The ‘decline’ being spoken of was not a decline in measured temperatures (which were in fact rising during the period) but had to do with an estimated temperature derived from tree ring data. The term ‘trick’, while misleading here, is common in scientific parlance for an elegant approach to processing data. ‘Mike’s Nature trick’ refers to using the same approach as another researcher (Prof. Michael Mann of Pennsylvania State University) in an earlier paper. Importantly, no less than seven separate inquiries have reviewed the correspondence and cleared the researchers involved.[x]
The release of this and other emails caused a media storm. Some elements of the media and anti-climate change activists were quick to take quotes out of context, and to advance the line that climate scientists were involved in a vast conspiracy motivated by the perpetuation of research funding. Even though the researchers concerned were cleared, ‘Climategate’ remains part of the vernacular in the climate debate, and is still cited by those wishing to discredit climate science. Such use of the scandal is ignorant at best, and malevolent at worst.
The same level of scrutiny is not necessarily applied to commentators for their forays into the scientific realm. British columnist James Delingpole, a prominent critic of the international climate science community, made the following comment in an interview on BBC2’s Horizon program in early 2011:
It is not my job to sit down and read peer reviewed papers because I simply haven’t got the time, I haven’t got the scientific expertise. What I rely on is people who have got the time and the expertise to do it and write about it and interpret it, you know. I am an interpreter of interpretations.[xi]
By his own admission Delingpole does not have the scientific training to assess the scientific literature. Moreover, he hasn’t even attempted to! Yet somehow he has chosen to rely on the small minority who dissent from the mainstream position, and to prosecute their minority position with fervour through the pages of a major British newspaper. It does not serve the pursuit of good policy outcomes to have commentators pushing fringe views about scientific matters without any scrutiny from those with relevant expertise.
Even with such a confused public discussion, there are precedents for effective public policy outcomes which are reliant on science. The depletion of the earth’s ozone layer (first observed in the late 1970’s) was attributed to the destruction of ozone by certain chemicals which were used as refrigerants and propellants.[xii] As in the case of climate change, the association of these chemicals with ozone depletion was disputed in some quarters, and arguments advanced in order to refute their responsibility for ozone depletion.[xiii] Ultimately, the scientific consensus prevailed, and action was taken to phase out the offending chemicals under the United Nations’ ‘Montreal Protocol on Substances that Deplete the Ozone Layer’. The Montreal Protocol, with 197 signatory states, is the first UN environmental treaty to achieve complete ratification.[xiv] Moreover, it has been described by former UN Secretary General Kofi Annan as ‘perhaps the single most successful international environmental agreement to date’.
Why is the scientific knowledge about ozone depletion accepted whereas that about climate change is disputed? Both concern environmental problems with potentially dire consequences and both have scientific dissenters. Yet in one case policy makers were persuaded and acted decisively, in the other the consensus has been denied and the policy makers are wavering accordingly. One explanation is that the debate about the response to climate change is so fractious that those wishing to avoid any costly action have sought to encourage sufficient doubt to remove the public appetite for action. The challenge for the climate science community is to have their work utilized by policy-makers in a way that acknowledges the integrity of their science. There is an acknowledged uncertainty in the study of the climate – this is not something which the climate change community has attempted to hide. But even with that uncertainty there is a broad agreement across the major learned academies that man-made climate change is occurring. That this is not appreciated by policy-makers represents both a failure of science communication, and an intrusion of ideological and political considerations into a debate that is ultimately about scientific truths.
The question for policy-makers should ultimately be one of risk assessment, not of the validity of climate science. What are the risks associated with the changing climate, and how might those risks be addressed? Evaluating risk involves assessing (i) the likelihood of an event occurring, and (ii) the consequence of that event. As such, scientists, with their calculations of outcomes and associated uncertainty must be involved in the policy discussion. Importantly, if 5% of the scientific community say there is no need for action, is that sufficient grounds to ignore the assessment of the other 95%? Ultimately, judgments about likelihood and consequence should be made with the best available information, which would generally be supplied by scientists. Policy-makers, armed with that information, need to make a judgment about what level of risk is appropriate to bear, and what courses of action (if any) should be embarked upon to reduce the risk. In other words, it is to the response to climate change that the activity and ingenuity of policy-makers should be deployed, not to questions of its existence.
How, then, should Christians think about the climate change discussion here in Australia and abroad? Firstly, we need to approach the debate as any good citizen should, with humility, recognizing the limitations of our own expertise. I have a background in the sciences, and have completed doctoral level studies in my own branch of science (macromolecular chemistry). That, however, does not qualify me to make judgments about the validity of climate science, in all its multidisciplinary complexity. We need to approach expert writings respectfully, recognizing the time, thought and learning which underpins any scientific study. The debate in Australia has been complicated by wild conjectures made by the politico-media complex, conjectures that are elevated to the status of ‘theory’ and that assume a level of credibility which is completely unwarranted. Christians should be people who listen thoughtfully, discerning the voices best qualified to speak on climate science, and these are most likely to come from the scientific community that have engaged with data, asked hard questions and endeavoured to find the answers by careful observation and measurement.
That said, I am not advocating an expert culture wherein we slavishly accept the word of proclaimed authorities without good reason. As with Christian teaching, we need to be those who ‘test and approve’. We should be prepared to go to the source, just as the reformers called Christian people back to the Bible as the foundation of Christian faith. We need to listen to scientists directly, rather than through the prism of our preferred commentators. Although the IPCC Assessment and Synthesis Reports are lengthy and technical, there are reliable plain English summaries available, such as the statements made by the American Association for the Advancement of Science and The Royal SocietyMy view is that people ought to be skeptical when politicians and commentators present minority scientific views with fervor, and use these views as a justification for inaction on an issue with potentially catastrophic consequences. (Of course, we will never recognize minority scientific views unless we are listening to the scientific community in the first place.) Such an approach is colored by ideology, choosing an expert to support a conclusion already drawn.
Of course, accepting a prevailing scientific position does not equate to automatically supporting particular policies regarding that position, or supporting any action at all. Whether climate change is best addressed via a carbon tax, an emissions trading scheme or so-called ‘direct action’ is a completely separate question to whether anthropogenic climate change exists. Any proposed response will have strengths and weaknesses, and might or might not be successful. We should examine approaches for responding to climate change on their merits, and draw on the wisdom of economists, social scientists, business, NGOs, and scientists as we contemplate our own personal position.
If, looking at the evidence, we are persuaded that anthropogenic climate change exists and that it requires a response, we should remember that those for whom the impacts of climate change will be felt hardest are generally among the world’s poorest people. It is those who live in low lying areas who are most vulnerable; those who have little or no means to escape rising sea levels, increased storm surges or decreasing supply of potable water. As Christians in a globalised world we need to remember that these people are our neighbours and that they are loved by God. A Christian response, whatever that might be, should reflect that they are loved by us, too.
[i] N. Oreskes ‘The Scientific Consensus on Climate Change’ Nature vol 306, 2004, 1686-1687.
[ii] ‘I Can Change Your Mind About Climate’, ABC Television, Thursday 26th April 2012
[iii] This is the so-called LD50 value, the dose of a particular agent which will be fatal to 50% of any given population. The value quoted for lead nitrate is that given by the International Lead Association. See http://www.ila-lead.org/UserFiles/File/factbook/chapter7.pdf
[iv] Values can be computed for LD50 in the toxicology experiments, and for the solubility product (Ksp) in the chemical experiment.
[v] For instance, there will be variations between individuals in general health, and consequently in their ability to metabolise toxicants.
[vi] J. R. Petit, J. Jouzel, D. Raynaud, N. I. Barkov, J.-M. Barnola, I. Basile, M. Bender, J. Chappellez, M. Davis, G. Delaygue, M. Delmotte, V. M. Kotlyakov, M. Legrand, V. Y. Lipenkov, C. Lorius, L. Pépin, C. Ritz, E. Saltzman & M. Stievenard ‘Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica’ Nature vol 399 1999, pp 429-436
[vii] D. J. Beerling and D. L. Royer ‘Reading a CO2 signal from fossil stomata’ New Phytologist vol 153 2002, 387-397.
[viii] C. D. Charles, J. Lynch-Stieglitz, U. S. Ninneman, R. G. Fairbanks ‘Climate connections between the hemisphere revealed by deep sea sediment core / ice core correlations’ Earth and Planetary Science Letters vol 142 1996, 19-27.
[ix] Climate Change 2007: Synthesis Report. A Report of the Intergovernmental Panel on Climate Change http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_synthesis_report.htm
[x] The researchers involved were cleared by reviews by the House of Commons Science and Technology Committee, The Science Assessment Panel, Pennsylvania State University, The US Environmental Protection Agency, The Independent Climate Change Email Review, The National Science Foundation, and The Inspector-General to the US Department of Commerce.
[xi] “Science Under Attack”, Horizons BBC2 24th January 2011.
[xii] The chemicals involved in ozone depletion are halocarbons such as chlorofluorocarbons (CFCs), halons, freons and other organic bromides and chlorides.
[xiii] For instance, some ozone depletion sceptics contended that the chemicals in question were too heavy to reach the ozone layer. This ignores the fact that the earth’s atmosphere, at least up to the level where ozone is present, is a well mixed system and as such the chemicals were undoubtedly present in the ozone layer.
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