With Simon Singh's somewhat crude contribution to the climate debate still ringing in our ears, my mind turned to an email I received recently on the subject of taxonomy in the climate debate. The message was from David Henderson and contained an excerpt from an article he had written which considered the subject of suitable terms to describe friend and foe alike in this most heated of debates.
It is often claimed that there now exists a world-wide scientific consensus on climate change issues, sometimes described as ‘overwhelming’. I believe that such language is inappropriate; but I think it is correct to say that alongside the official policy consensus (which is a reality), and providing both rationale and support for it, there exists an established body of what I call prevailing scientific opinion.
Predictably, received opinion is not universally shared. It remains subject to challenge by a varied collection of doubters, sceptics, critics and non-subscribers: I will label them collectively as dissenters. Against these, and greatly outnumbering them, are arrayed what I term the upholders of received opinion. Among economists, a clear majority of those who have expressed views on these matters can be classed as upholders.
Within both groups — and this is important to note — there are different schools thought: a whole spectrum of opinions can be identified. Each of the many subject areas, including ours and those of the different sciences involved, has a spectrum of its own. At one end of each spectrum are what may be termed strong or full-blown upholders, the dark greens so to speak. Prominent among these are Lord Stern and the team that worked under him to produce the Stern Review: the Review takes the position that AGW ‘presents very serious global risks and demands an urgent global response’. At the other end of the spectrum, strong dissenters — the dark blues — argue that such warming, if indeed its extent can be shown to be significant, is not a cause for alarm or concern: hence measures to curb emissions should be eschewed — or discontinued, where they are now in place. In between these two far removed positions, there are upholders and dissenters who hold more limited or qualified beliefs. I count myself as a light-to-medium blue — a limited dissenter, though a firm one.