Published in Crossbow – The Bow Group Magazine, October 2006, pp. 14-15

Try to sum up what the Enlightenment stands for. You would have to include reference to general scepticism towards doctrines, belief in science and empirical methods, use of reason and the possibility of doubt. Many blessings of the modern world are founded on the principles which blossomed during the Age of Enlightenment, thanks to those scientists and inventors who challenged what the late economist John Kenneth Galbraith labelled “conventional wisdom”. Michael Faraday was derided for his idea of generating electricity by moving a magnet in a coil of wire; the Wright Brothers were warned by the president of the Royal Society, Lord Kelvin, that heavier-than-air objects could not fly. But whenever we use electricity or board a plane we benefit from their discoveries, which would have never occurred if they had listened to the prevailing views of their time. It is this kind of fearless enquiry which broadens our understanding of the world and drives progress.

Science is no place to expect to find final truths: Science is built upon doubt and constant enquiry. As Sir Karl Popper, the Austrian-born British philosopher put it, “Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve” (Objective Knowledge: An Evolutionary Approach, 1972). To Popper, science was never finished but a constantly evolving process.

So imagine what Sir Karl would make of the current debate about climate change. In April of this year TIME magazine devoted almost an entire issue to the topic of “climate change”, and on the front cover it boldly declared: “Be worried. Be very worried. Climate change isn’t some vague future problem, it’s already damaging the planet at an alarming pace”. Tony Blair’s chief scientific adviser, Sir David King, warns us that climate change is the most severe threat we face today, more serious than terrorism. Even US president George W. Bush is now quoted saying that climate change is a “serious problem”, and his fellow Republican, California’s governor Arnold Schwarzenegger, effectively terminated the discussion: “The debate is over. We know the science. We see the threat posed by changes in our climate. And we know the time for action is now”.

Again and again we are told there is a broad consensus on climate change: But is this true? And can there ever be such a scientific consensus? To start with, “consensus” is a term which is alien to science. It comes from the terminology of sociology and describes a process of collective decision-making. But in science, such a process of establishing the “truth”, even if done by a majority decision, can hardly be an option. It would not only require the individual scientist to submit to a majority view, but it also makes this view virtually unassailable. Establishing a “scientific consensus” is incompatible with the way that science has evolved from the Age of Reason to Karl Popper’s theory of critical rationalism.

So let’s treat talk of “climate change consensus” as what it is: not scientific consensus, but at most a tacit agreement to pretend that most of the questions have already been answered. But this obscures the fact that there are indeed very few things that most climate scientists would readily agree on. What are these widely accepted propositions? First, the global average temperature has risen by around 0.7 degrees Centigrade since 1860. Second, a world population of more than six billion people has an influence on the climate through its energy use and also through land-use changes. Everything else in the climate change debate is highly controversial. Has the climate of the past millennium always been colder than today or not? How much of an effect on the climate does atmospheric carbon dioxide have? Do rising carbon dioxide concentrations lead us to a point of no return or are there self-regulating mechanisms in nature which will prevent this from happening? There is wide disagreement among climatologists on all these questions, and this kind of disagreement is to be welcomed. After all, this is what science is all about.

So far from having reached a clear-cut consensus there is intense debate about climate change. But why do public always get the opposite impression? Because of the way in which the climate change debate is conducted. In 1988, an Intergovernmental Panel on Climate Change (IPCC) was established by the World Meteorological Association and the UN Environment Programme. It has since produced three substantial assessment reports on the scientific basis of climate change, which have been compiled by hundreds of scientists. A fourth report will be published next year.The IPCC assessment reports have been remarkable achievements in bringing together scientific expertise, and the IPCC has to be commended on this. Yet, at the same time the IPCC process brings with it some serious problems. The first is that the scientific content of the reports is far too complex to be understood by non-scientists, and it is unlikely that anyone would read several hundred pages of scientific evidence. To overcome this problem, the IPCC provides a “Summary for Policymakers”. But this summary is as much by policymakers as it is for policymakers: its wording is determined not by scientists, but by governments; the contents less a reflection of the breadth of the scientific discussion, than an exercise in political “consensus-building”.

It is also questionable whether the IPCC has adequately dealt with criticism from outside. First, the treatment of the economics of climate change: In order to estimate future carbon emissions, you must forecast the global economic development over a long period of time. This in itself is tricky. There are many unknowns like population growth or technological advances. The IPCC had based its predictions on the assumption that the least developed countries will over time catch up with today’s rich nations in their per-capita incomes. While this may be plausible, the way in which it had been modelled clearly is not. Instead of estimating the developing countries’ economies based on purchasing power parities – a standard method in economics – the IPCC used exchange rates. In several papers David Henderson, former OECD chief economist, and Ian Castles, former head of the Australian Bureau of Statistics, demonstrated that this led the IPCC to seriously overestimate future global economic growth. In one of the scenarios used by the IPCC even North Korea achieved a higher per-capita income than the US in 2100. The IPCC first ignored and then rejected this criticism. However, when the House of Lords Select Committee on Economic Affairs produced a report on the economics of climate change last year, it acknowledged that Henderson and Castles were not only right to raise the issue, but concluded that the IPCC’s use of economic scenarios contained “questionable assumptions and outcomes”. The Lords also found the IPCC process “apparently influenced by political considerations”.

Another Parliament has also expressed its concerns over the IPCC process. For years Canadian economist Ross McKitrick and mineral consultant Steven McIntyre had criticised the so-called “hockey stick curve”, which features prominently in the IPCC’s third assessment report and the summary for policymakers. It shows that temperatures had basically been cold and unchanged for the first eight centuries of the second millennium and then started to rise steeply. This was meant to demonstrate the effect of carbon dioxide emissions. However, McIntyre and McKitrick claimed that the methods used to calculate the hockey stick curve were flawed. This triggered an investigation by the US House Committee on Energy and Commerce. Three renowned professors of statistics were commissioned to evaluate whether McIntyre’s and McKitrick’s accusations were justified. The result of their report left no doubt. It found a misuse of statistical methods, a lack of effective peer review and a lack of scrutiny in the preparation of the IPCC’s assessment report. The judgement on the IPCC could hardly have been harsher.

What all this means is that the desire to establish and defend a “consensus” has seriously damaged the very basis of our understanding of climate change. This is regrettable. It has done a disservice to science, which should be an open enquiry process in which scepticism is regarded as a virtue, not a vice. Even worse, the doctrine of a “climate change consensus” has also narrowed the political debate on how to deal with carbon emissions when the true scope should be much wider. We should call for an open debate which would include the economic costs of emissions restrictions and the alternative of adaptation to new climatic conditions. We could then also discuss whether it is wise and ethical to invest large sums of money in the fight against climate change with an uncertain result when the same money could save millions of lives with certainty if spent on fighting malaria or malnutrition, for example.