None of us are perfect. Like Canon Chasuble, I myself, for example, am peculiarly susceptible to draughts. Worse than that: I once submitted several decades of revised data on the annual mass balance of White Glacier in northern Canada to the World Glacier Monitoring Service in Zürich – and managed to date all the balances wrong by one year. Fortunately, I noticed the blunder and was able to correct it but this story illustrates an important truth: blunders happen.
I am not the only glaciologist, nor the only scientist, to have blundered. One weakness of WGMS is that, being underfunded, it doesn’t thoroughly check the data submitted to it because it can’t afford to. In fact, my blunder would have been quite hard for anyone but me to detect. But for anything more intelligent than lists of raw numbers, science has a way of testing the validity of claims. It is called peer review, in which we insist that results not be published until they have been given a thorough going-over by more than one qualified colleague. This is far from a guarantee of correctness, but long experience shows that it is far better than doing nothing.
I recently came across a collection of blunders in no less a place than the second volume, known as WG II, of the Fourth Assessment Report of IPCC, the Intergovernmental Panel on Climate Change. WG II reproduced an unreviewed claim that Himalayan glaciers are very likely to disappear by 2035. The claim was first made in 1999 in a more restricted way, concerning only the central and eastern Himalayas, in a news story in New Scientist, and slightly earlier in an Indian electronic magazine Down to Earth. According to Google, it has been repeated hundreds of thousands of times, presumably in trusting good faith every time. One recent repetition was by Rajenda Pachauri, the Chairman of the IPCC.
It is a tangled story, but in essence the claim is wrong because the date 2035 seems to be a hasty misreading by somebody, now unidentifiable, of the date 2350 in an obscure report. In its context, 2350 was a reasonable date, but changing it to 2035 turns the claim about the disappearance of Himalayan glaciers into garbage.
There is no comfort for climate sceptics in this. A few years ago one of them, a botanist writing to New Scientist, tried to reason from the supposed fact that 555 out of 625 glaciers reported to WGMS were advancing. This claim provoked the not very scientific but understandable response from WGMS spokesperson Frank Paul that, “This is complete bullshit”. Investigation showed that there were two levels of wrongness about the claim. Superficially, it was wrong because the sceptic had failed to press the Shift key: he should have typed 55%, not 555. More deeply, it was just plain wrong. The sceptical article was the start of a trail, traced impressively by George Monbiot, that leads back to a non-existent paper not published in Science in 1989.
Depending on what set of years you look at in the real WGMS records, the actual percentage of advancing glaciers is usually nearer to 5.5% or even 0.55% than 55%. It did approach 55% between 1975 and 1985, but, as Figure 5.1 in the WGMS summary of glaciological facts and figures makes clear, the global percentage is distorted by the over-representation of measurements from central Europe. A well known cooling peaked at about the period 1965-1970 in the Alps, which are much studied but host only a tiny proportion of the world’s glaciers.
Like me and Canon Chasuble, peer review is not perfect, but there is no question that it reduces the risk of blunders happening and wasting everybody’s time. "Everybody" includes concerned lay folk as well as the scientists. One partial antidote to the effects of blunders that is available to all, including those who have to take the experts’ words on trust, is the first of Bertrand Russell’s ten commandments for liberal thinkers: “Do not feel absolutely certain about anything.”