In a previous posting, I argued that it is important for everyone to have some understanding of climate science—which is why Medact produced a summary and discussion of the latest UN report about the physical science of climate change. I also questioned the scientific understanding of Owen Paterson, minister for environment, food, and rural affairs, following his ill judged comments on the UN report. But why is there is so much scepticism and denial about the evidence of anthropogenic global warming?

A useful Wikipedia definition of climate change denial is: “a set of organized attempts to downplay, deny, or dismiss the scientific consensus on the extent of global warming, its significance, and its connection to human behaviour, especially for commercial or ideological reasons.” Various degrees of denial exist, ranging from the denial of global warming itself; to the acceptance of global warming but the denial that human influence is a cause; to the acceptance of anthropogenic global warming but a denial of its threat.

There are also different groups of denialists. For one group, denial is manufactured for the purpose of protecting vested interests. The fossil fuel industry falls into this category. Another group consists of people who are eccentric and idiosyncratic, or attracted to the notoriety and celebrity status that is associated with being a contrarian. For a third group, denial is a psychological manifestation—emerging out of fear or a sense of helplessness; or rooted in an ideological or faith based rejection of anything that is incompatible with fundamental beliefs.

According to Stephan Lewandowsky and colleagues from the University of Western Australia, a libertarian, free market world view is a strong predictor of being a climate change denier—a finding that is consistent with the theory of “motivated reasoning,” by which people selectively accept the information that supports their existing beliefs and values. Both the second and third groups are susceptible to and encouraged by the manufactured misinformation of the first group.

Denialism should be seen as distinct from legitimate scepticism. In the case of climate science, certain limitations of data and research methodology, as well as the extreme complexity of the earth climate system, inevitably mean that some degree of scientific uncertainty is inevitable. Evidence and theories need to be carefully evaluated and questioned with a process of peer review that should include debate and disagreement. Denialists however, use scientific uncertainty and the process of peer review to peddle misinformation and sow confusion (a problem which is then aggravated by inaccurate media reporting of scientific methodology and uncertainty).

The deliberate undermining of climate science is not unlike the organised campaign to undermine the epidemiology and clinical science of respiratory disease and lung cancer. In both cases, a corporate sector with immediate and direct vested interests (tobacco and fossil fuel companies) collaborated with a wider set of interest groups that are generally opposed to regulation and government intervention to undermine science and public interest policy.

The formation of an organised movement to undermine climate science (which emerged soon after the establishment of the IPCC) has been studied and well documented. See for example: Merchants of Doubt, McCright and Dunlap, and Greenpeace. The movement involves a large network of organizations, including corporations, think tanks, advocacy groups, trade associations, charities, and foundations, with strong links to sympathetic media outlets and certain politicians.

Robert Brulle’s (Drexler University, Philadelphia) study of the financing of the “anti climate science” movement in the United States shows that, where previously, funding for climate denialism was more clearly linked to oil companies, it is now largely underwritten by conservative billionaires, often working through anonymized funding channels. Kert Davies from Greenpeace has also noted that “the funding of the denial machine is becoming increasingly invisible to public scrutiny.”

In an article published in the European Journal of Public Health, Pascal Diethelm and Martin McKee describe five tactics commonly used to undermine science. The first tactic is to associate scientific consensus with a conspiracy. For example, in the United States, climate science is associated with a UN plot to undermine freedom and the country. Another example was the controversy around the leaked emails from the University of East Anglia in 2009 to imply a scientific conspiracy despite the lack of any evidence of fraud or scientific misconduct.

A second tactic is the use of fake experts—individuals bestowed with a false scientific legitimacy and then used to question the credentials of established experts and researchers. This often goes with the third tactic: the selective ‘cherry-picking of isolated studies that challenge the dominant consensus or of flaws in the weakest papers that support the dominant consensus. A fourth tactic is to create impossible expectations of what science and research can deliver—for example, claiming that the evidence of global warming isn’t strong because it is not underpinned by randomised controlled trials. And the fifth tactic is the use of logical fallacies, “red herrings” and “straw men” to misrepresent the science—for example, using episodes of extreme cold weather to deny global warming.

Such tactics are alive and well. See here for a very recent televised debate between organised denialism and science.

In some instances, tactics extend to the aggressive intimidation of scientists—a strategy that is given greater potency by the erosion of academic independence and the growing reliance on private funding for research. In the US, a Climate Science Legal Defense Fund has been established to help scientists conduct research without the threat of politically motivated attacks. See here.

While climate denialism is especially extreme in the United States, it is also present in Europe. The European Institute of Climate and Energy, for example, is a group of climate denialists whose president said in an open letter to Chancellor Merkel in 2009: “[H]umans have had no measurable effect on global warming through CO2 emissions. Instead the temperature fluctuations have been within normal ranges and are due to natural cycles. Indeed the atmosphere has not warmed since 1998—more than 10 years, and the global temperature has even dropped significantly since 2003.”

In the UK, organized denialism is exemplified by Nigel Lawson’s Global Warming Policy Foundation (GWPF)—a registered educational charity funded by anonymous donations. The GWPF website uses for its masthead, a graph of global air temperature covering the period from 2001 to 2012. This is a period of time during which there was an observed reduction in the rate of global warming—a phenomenon that has been called a “pause” in global warming. This phenomenon however, has been explained and has never negated the facts of a longer term warming trend since the pre-industrial age nor the fundamental heat-trapping effects of greenhouse gases. The masthead is a good example of data misrepresentation and cherry picking. A GWPF report published last November concluded that global warming and extreme weather “pose no threat to humanity, either at present or in the next 10 to 25 years.”

In a study of climate skepticism, Stuart Capstick and Nicholas Pidgeon note the difference between “epistemic scepticism” (where people doubt the reality or causes or climate change) and “response scepticism” (where people dispute the efficacy of acting to tackle the problem). Their research suggests that response scepticism is more strongly associated with a lack of concern about global warming, and argue that this is less bound to issues of science than it is to broader societal questions for which there is no right or wrong answer. For example, how much influence should governments have over people’s lives? To what extent should industry be regulated? They suggest that response scepticism may also emerge from perceptions that climate change is too large and complex a problem to solve; as well as with wider cynicism about governments, the UN and politics in general.

In many ways, it is response scepticism (rather than epistemic scepticism) that should exercise our minds. But what is the antidote? An emerging academic literature is concerned with answering this question and includes the study of more effective collective action, concepts of environmental citizenship and participatory democracy. We can and must overcome the response scepticism—and the health community should be at the forefront of this.

Declaration of Interest: I am chair of the Board of Trustees of Medact. I have no other competing interests to declare.

David McCoy is a public health physician. He spent his first 15 years working in clinical medicine and health systems development, mostly in South Africa. Since then he has been based in London, working on various aspects of “global health” as an academic and NHS physician. He is a senior clinical lecturer at Queen Mary University London, and chairs the Board of Trustees of Medact. He was joint managing editor of the first two alternative world health reports (Global Health Watch) and is a member of the steering committee of the People’s Health Movement.