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A Guide to the Climate Debate

    A widespread misunderstanding of the climate debate is that it consists of two sides divided on the claim that “climate change is real”, which one side believes and the other “denies”. This representation is false. Most people who are called ‘sceptics’ and ‘deniers’ do not argue that climate change is not ‘real’. But worse than this, the oppositional framing of science-vs-denial obscures the actual substance of scientific, political, economic and moral arguments underpinning these disagreements, depriving the public of a vital debate about society’s future.

    The climate debate, if it were allowed to happen, would be in fact a debate about a constellation of claims. And rather than being claims which can be judged simply as either true or false, they are questions of degree. For example, it may well be true that “climate change is real”, but evidence that CO2 emissions have caused the atmosphere to warm and to have altered the climate is not equivalent to evidence of a ‘climate crisis’. Only debate can expose these nuances, to show what science can and cannot tell us about how to make the best of the future.

    Below is a map of the climate debate, which shows how arguments move from global warming science through to policies to mitigate the problem. As is clear from the map, rather than being a single proposition ( like “climate change is real”), many issues exist between global warming and policy. This is because global warming in itself is not the issue that concerns anyone. What matters are the consequences of global warming. According to environmentalists, global warming will cause climate change, which will alter the world (‘climate impacts’), making it hostile to human society (‘climate crisis’). The map indicates the key claims that this argument consists of and unpacks them into a logical sequence of columns. There are many more issues not shown here, but this map of the debate is intended to give an overview.

    The map shows how this argument moves from an understanding of the function of greenhouse gases in the atmosphere, through first, second, and Nth-order effects of global warming, and through social effects, to policy formulations that are intended to reduce emissions. On the left of the map are the scientific claims relating to the basic physics of global warming: the properties of greenhouse gases and their functioning in the atmosphere. To the right of this are columns which group related claims in the order of their effect: global warming causes climate change effects, which in turn cause climate impacts, which cause the climate crisis. Finally, climate policy aims to mitigate global warming. Between each column are boxes that indicate the role of modelling in understanding how the preceding column influences the later column.

    Each entity on this map is clickable, and will take you either to an article on the subject, or to a page with a list of articles on that category. Each article discusses the issue and provides links to further information and discussion.

    We have produced a short video explaining the map.

    This map shows that, whereas the conventional understanding, as described above, of the climate debate divided on a single claim, there are at least five main categories of claims, containing around 30 claims within them, which are the subject of more or less controversy, and which are questions of degree rather than true-or-false propositions. How much we believe that the fact of global warming (the leftmost column) makes climate policy (the rightmost column) an imperative depends on how strong we believe that the claims in the three columns between them are, and how safe the progress between them is. Moreover, now that the UK, and many other countries’ climate policies are now in their third decade, we now have plenty of evidence to begin to evaluate the policy on its own terms: is climate policy any less damaging than climate change?

    Scientific certainty and global warming

    One thing to observe from this map is that scientific understanding and certainty decrease from left to right. The thermal or ‘greenhouse’ properties of CO2 are relatively uncontroversial. Even climate scientists who are called ‘deniers’ agree with this basic premise, though a small number of people offer alternative accounts of global warming physics.

    There is significant scientific agreement on the contribution of CO2 to warming because the effect of CO2 can be measured in laboratory conditions and relatively safely applied to the whole atmosphere. According to most analyses, a doubling of atmospheric CO2 over pre-industrial levels would cause around 1°C of warming. But this amount of warming is not sufficient to substantiate the more alarmist interpretations of global warming and its consequences.

    Climate feedback mechanisms

    More controversy enters the debate on the subject of feedbacks. These are shown on the map as orange arrows connecting some entities (Deforestation, Sea ice loss and Glacial recession & ice sheet loss) to the Climate feedbacks entity, which either contribute to cooling (negative feedbacks) or more warming (positive feedbacks) to the atmosphere. Scientists are much more divided on the net contribution of positive (warming) and negative (cooling) feedbacks. In the past, some climate scientists argued that the overwhelming influence of positive feedback mechanisms could lead to ‘runaway global warming’ — warming causing more warming, causing more warming… and so on. But this idea, though persistent, is now outside of mainstream scientific opinion.

    Climate modelling

    In order to reconcile this debate, simulations of the climate (models) are used to try to gain insight into the processes at work in the atmosphere and natural environment. Scientists believe that if models can show skill at reconstructing the past climate, then this will verify the current state of scientific understanding (of feedbacks and more), and allow the future climate to be predicted with confidence, serving the policymaking process.

    But these climate models have done more to add controversy than to resolve it. It is uncontroversial that climate models have been shown to ‘run too hot’, leading to greater estimates of climate impacts. Consequently, accusations have been made that researchers allow bias into their work, which due to the complexity of computer simulations, poor coding and documentation, and protection of intellectual property, are hard to examine.

    Some researchers argue that the climate is perhaps simply too complex to model mathematically, i.e. using computer models, and that such simulations are therefore inherently flawed.

    Controversy, uncertainty and bias

    Thus, the fundamentals of climate change begin — in the leftmost column — amid much more controversy than is admitted to by many climate advocates, from science through to policymaking. These errors can be seen in claims made in the recent past that dramatic effects of climate change can be seen already, or would become visible in the near future. For example, many claims have been made that extreme weather has become more frequent and more intense, but weather statistics do not support such claims in many cases. And where observational science does show detectable changes in extremes, these effects are very far from the dramatic climate impacts that are used to make claims about a ‘climate crisis’. As the articles available from the Climate crisis category column shows, there is very little evidence supporting it, and a great deal of evidence against it.

    Confusing hypothesis for fact

    Data from computer simulation and from ‘narratives’ that emphasise worst-case scenarios is not evidence from the real world. Yet often, projections and analyses that claim to have identified evidence of manmade global warming in climate change, climate impacts, and in ‘climate crisis’ to urge climate policy are owed not to real world observations. Sceptics argue that claims of this kind are not science, but closer to speculation. They are given the weight of scientific authority by the scientists and scientific institutions that produce them. But they are hypotheses, which are untested against reality. In this way, hypotheses are presented to the public and policymakers as evidence and fact.

    Remapping the climate debate

    Our map of the debate shows how the climate debate is far more complex than is presented by politicians, the media, campaigners, and even some climate scientists. And it shows how unsound arguments, based on little to no real world data, can get obscured in the broader debate, amid urgent demands for political action. However, care should be taken to see this not as a claim that there is no such thing as climate change, or that climate change is not a problem, but that a number of tendencies act against a sober reading of what the available science can tell us. These include groupthink, political narratives and ideology, and other, simpler human motivations that normal science and academic research may not be well set up to exclude.

    This guide has been an overview of how the columns of the map relate to each other. Clicking on one of the category columns will take you to a further guide to the topics in that category, each with an overview of the evidence.

    Further Reading & Viewing