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Since its creation in 1988, the IPCC has made it increasingly clear that global warming is largely the result of anthropogenic causes such as industrial pollution, vehicle emissions, deforestation and the burning of fossil fuels, all of which release greenhouse gases into the atmosphere. Although the evidence base is large, diverse and consistent, there are still contentious debates around the thesis and its implications which bring the consensus view into conflict with a small number of ‘climate change sceptics’.

The IPCC (2015: 2) says that ‘Warming of the climate is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.’ Yet some question the evidence that global warming is actually occurring at all. Lord (Nigel) Lawson (2009: 1), former energy secretary and chancellor in the UK government, maintains that global warming is ‘the latest scare’ in a series that includes overpopulation and total resource depletion. Lawson argues that there was a ‘mild warming’ in the last quarter of the twentieth century, but this has been followed by a ‘lull’ in the twenty-first century when warming has apparently ‘stopped’. The sceptical charge here is that climate scientists fail to deal adequately with contrary evidence and either ignore it or cherry-pick their evidence. Yet in 2011, the government’s chief scientific adviser, Sir John Beddington, engaged in an exchange of letters with Lawson, arguing that his book showed little grasp of climate science, that short-term temperature trends are not meaningful in the context of long-term global warming, and that the scientific evidence from multiple sources clearly showed that ‘the risks are real’ (Boffey 2011).

Second, some sceptics argue there is good evidence that global warming is real but deny an anthropogenic cause. For this strand, global warming is an entirely natural phenomenon, probably related to the fluctuating activity of the sun. They also claim that CO₂ is not a significant greenhouse gas. As solar activity fluctuates, so does the Earth’s climate, and this explains the current warming trend. The majority scientific view is that solar activity does affect surface temperature, but there is no evidence of a positive trend in solar activity since the 1960s that could have produced the present global warming. CO₂ is certainly not the only greenhouse gas, but it does remain in the atmosphere for many decades and even centuries, which leads to a steady accumulation over time from industrial activity. It is this, say the majority, which mainly accounts for global warming.

Third, even if we accept that global warming is real and is partly explained by industrialization, some argue that the predicted consequences are highly speculative at best and grossly exaggerated at worst. Computer modelling of the kind used by the IPCC is notoriously unreliable, especially when extrapolating current trends far into the future, and suggestions of a 6°C rise by 2100 amount to scaremongering. Politically, economically and socially, our efforts would be better directed at tackling other more urgent social problems, such as poverty in developing countries, rather than wasting valuable resources on an uncertain ‘problem’ (Lomborg 2001).

Although some forecasts at the extreme end of climate science do suggest an increase of 6°C is possible by 2100, this assumes no change in the policies of governments aimed at reducing carbon emissions – already an outdated assumption. We must bear in mind that there are many uncertainties in climate forecasting, including cloud feedback, changing ice-sheet flows in Antarctica and Greenland, landuse change, technological developments, the impact of aerosols, the extent of behavioural changes and a lack of data in some regions, which hinder accurate modelling.

Given the global situation, it is not possible to rule out completely the more radical and devastating effects of global warming this century. Nevertheless, the history of environmental politics in the twentieth century is littered with failed predictions of global disaster and catastrophic societal collapse, so it makes sense for social scientists to work with the best available scientific research, which is currently the ongoing IPCC programme. It is also correct that computer modelling can conflict with real-world evidence, but the IPCC climate models are complex and built on evidence gathered from many sources around the world. The Fourth Assessment Report noted that, since 1990, IPCC forecast values have averaged 0.15 to 0.3°C increase per decade, which compares favourably with the observed increase between 1990 and 2005 of 0.2°C per decade. Such evidence suggests that the IPCC modelling is, in fact, the most accurate we have.

The ‘ClimateGate’ affair, discussed in ‘Using your sociological imagination’ 5.2, has been a salutary experience, not just for climate scientists, but for the academic community as a whole. In an increasingly global academic environment, which operates within societies where easy access to the internet and ideals of freedom of information combine to create expectations of open access to information and data, scientific practice often seems to be catching up. It is certainly not unusual for groups of scientists to guard jealously their raw data in order to protect their own knowledge claims, and, although it is common to speak of a ‘scientific community’, it is important to remember that scientific work, like all other spheres of social life, is highly competitive. For the foreseeable future at least, it is likely that an uneasy tension between established scientific practice and the emerging culture of open access to information will continue.