Consensus and dissent

Ipsos MORI reports that 56% of British adults agree with the statement "Many leading experts still question if human activity is contributing to climate change", and suggests that people have been "influenced by counter-arguments". Al Gore, who helped to organise last week's Live Earth event, remarked that "those people think, wrongly, that the scientific debate is still raging." The Royal Society's vice-president commented: "People should not be misled by those that exploit the complexity of the issue, seeking to distort the science and deny the seriousness of the potential consequences of climate change. "

The global warming controversy raises issues about (a) what is meant by "scientific consensus" and (b) the extent to which politicians and voters ought to accept what scientists agree is fact or highly probable. There is also the question of whether views which depart from the consensus should be suppressed because they are likely to be false, or promoted because they maintain a healthy debate and prevent thinking from becoming stale and dogmatic.

It seems clear that a majority of scientists support the idea that it is "very likely" that the gradual increase in temperature over the last century is "predominantly" due to human activity. But should we be interested in the views of those working in areas other than climate change? For example, the views of the Australian Medical Association in effect form part of the "consensus", but are they relevant? It is interesting that the most recent statement by the American Meteorological Association sounds more guarded than similar statements by other groups of scientists. Climatology is a highly complex subject: modelling conditions even a few weeks into the future generates results that are notoriously unreliable.

Many believe there is a high risk that CO₂ emissions over the next few decades, unless actively restricted, will create significant and damaging climate change, and think additional environmental policies are therefore urgently needed. And for many of these people, persuading the voting public to agree to such policies is seen as a crucial obstacle. For them, climate change sceptics are simply holding up the necessary shift in public perceptions.

While there does seem to exist a consensus of sorts, we need to bear two things in mind. The first is that what is relevant is not whether there exists a consensus among the highly educated, or among scientists or academics in general, but whether those who are expert in the field in question are in agreement, and whether that agreement is unanimous or merely in the majority. Second, we know from past experience that consensus in itself does not conclusively demonstrate correctness, especially if the issue in question has political implications.

Assuming for the sake of argument that there is a consensus among climate scientists, and that the consensus should be given due weight, there is still an argument that opposing viewpoints should actively be given publicity, both from a utilitarian and a libertarian viewpoint. Consequentialism in science does not seem like a good idea.

Other articles
Dizzy on the politicisation of science
Acton Institute blog on Live Earth
Stumbling & Mumbling on climate moralising
BBC's The Investigation on the Stern Review
Crooked Timber endorses the Stern Review
Crooked Timber blames Exxon for scepticism
Carl Wunsch on "The Great Global Warming Swindle"
Nigel Lawson on climate change
Bjorn Lomborg on being vilified
Tim Worstall on IPCC forecasts