Isegoria

Matt Ridley recounts his life as a climate lukewarmer:

I am a climate lukewarmer. That means I think recent global warming is real, mostly man-made and will continue but I no longer think it is likely to be dangerous and I think its slow and erratic progress so far is what we should expect in the future. That last year was the warmest yet, in some data sets, but only by a smidgen more than 2005, is precisely in line with such lukewarm thinking.

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In the climate debate, paying obeisance to climate scaremongering is about as mandatory for a public appointment, or public funding, as being a Protestant was in 18th-century England.

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I was not always a lukewarmer. When I first started writing about the threat of global warming more than 26 years ago, as science editor ofThe Economist, I thought it was a genuinely dangerous threat. Like, for instance, Margaret Thatcher, I accepted the predictions being made at the time that we would see warming of a third or a half a degree (Centigrade) a decade, perhaps more, and that this would have devastating consequences.

Gradually, however, I changed my mind. The failure of the atmosphere to warm anywhere near as rapidly as predicted was a big reason: there has been less than half a degree of global warming in four decades — and it has slowed down, not speeded up. Increases in malaria, refugees, heatwaves, storms, droughts and floods have not materialised to anything like the predicted extent, if at all. Sea level has risen but at a very slow rate — about a foot per century.

Also, I soon realised that all the mathematical models predicting rapid warming assume big amplifying feedbacks in the atmosphere, mainly from water vapour; carbon dioxide is merely the primer, responsible for about a third of the predicted warming. When this penny dropped, so did my confidence in predictions of future alarm: the amplifiers are highly uncertain.

Another thing that gave me pause was that I went back and looked at the history of past predictions of ecological apocalypse from my youth – population explosion, oil exhaustion, elephant extinction, rainforest loss, acid rain, the ozone layer, desertification, nuclear winter, the running out of resources, pandemics, falling sperm counts, cancerous pesticide pollution and so forth. There was a consistent pattern of exaggeration, followed by damp squibs: in not a single case was the problem as bad as had been widely predicted by leading scientists. That does not make every new prediction of apocalypse necessarily wrong, of course, but it should encourage scepticism.

What sealed my apostasy from climate alarm was the extraordinary history of the famous “hockey stick” graph, which purported to show that today’s temperatures were higher and changing faster than at any time in the past thousand years. That graph genuinely shocked me when I first saw it and, briefly in the early 2000s, it persuaded me to abandon my growing doubts about dangerous climate change and return to the “alarmed” camp.

Then I began to read the work of two Canadian researchers, Steve McIntyre and Ross McKitrick. They and others have shown, as confirmed by the National Academy of Sciences in the United States, that the hockey stick graph, and others like it, are heavily reliant on dubious sets of tree rings and use inappropriate statistical filters that exaggerate any 20th-century upturns.

What shocked me more was the scientific establishment’s reaction to this: it tried to pretend that nothing was wrong. And then a flood of emails was leaked in 2009 showing some climate scientists apparently scheming to withhold data, prevent papers being published, get journal editors sacked and evade freedom-of-information requests, much as sceptics had been alleging. That was when I began to re-examine everything I had been told about climate change and, the more I looked, the flakier the prediction of rapid warming seemed.

I am especially unimpressed by the claim that a prediction of rapid and dangerous warming is “settled science”, as firm as evolution or gravity. How could it be? It is a prediction! No prediction, let alone in a multi-causal, chaotic and poorly understood system like the global climate, should ever be treated as gospel. With the exception of eclipses, there is virtually nothing scientists can say with certainty about the future. It is absurd to argue that one cannot disagree with a forecast. Is the Bank of England’s inflation forecast infallible?

Incidentally, my current view is still consistent with the “consensus” among scientists, as represented by the reports of the Intergovernmental Panel on Climate Change. The consensus is that climate change is happening, not that it is going to be dangerous. The latest IPCC report gives a range of estimates of future warming, from harmless to terrifying. My best guess would be about one degree of warming during this century, which is well within the IPCC’s range of possible outcomes.

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