Since the fading belief that the world is in the grip of runaway man-made global warming still threatens us with the biggest bill in history, it is rather important to know how far we can trust the science which is said to support that belief
A scientist examines an ice core sample in Iceland. Photo: ALAMY
One of the most vociferous cheerleaders in the cause has been the Nature, which calls itself “the world’s most prestigious weekly journal of science”.
Whenever some landmark event in the story is approaching – such as a world climate conference or a new report by the UN’s Intergovernmental Panel on Climate Change (IPCC) – Nature can be relied on to come up with a new paper purporting to refute one of the more embarrassing objections to the orthodox theory. However thoroughly such a paper is then dismantled by expert critics, it will remain established as a pillar of the orthodoxy.
In 1996, as the Kyoto treaty approached, it was a paper claiming to show how the “fingerprint” of warming – the part of the atmosphere where it was most obvious – confirmed that it must be due to human activity. Two scientists promptly explained how the data showed precisely the opposite – warming that was man-made should be greatest in the upper troposphere and not, as it actually is, on the earth’s surface. The chief author of that bid to defend the orthodoxy was Ben Santer. It was his last-minute rewriting of a key passage in the IPCC’s second report – contradicting the text agreed by all the scientists responsible – that provoked the IPCC’s first real scandal. Frederick Seitz, the eminent US physicist who exposed this flagrant breach of the rules, described it as the most “disturbing corruption of the peer-review process” he had come across in all his 60 years as a scientist.
In 1998, Nature published the first of the two iconic “hockey stick” graphs by an obscure young physicist, Michael Mann, which rewrote climate science by appearing to show that temperatures had suddenly shot up in the late 20th century to easily their highest level in history. Mann became the blue-eyed boy of the IPCC, which made his graph the centrepiece of its 2001 report. Only then was it exposed, by Steve McIntyre and Ross McKitrick, as a meaningless piece of artifice, created by a skewed computer model.
In 2009, months before the Copenhagen conference was planned to produce the most expensive treaty in history, Nature came up with a much-publicised cover story by Eric Steig and a team which included Michael Mann as its adviser on computer modelling. This claimed to show that, against all previous evidence, Antarctica had for 50 years been warming, not cooling. It took McIntyre and Anthony Watts’s science blog Watts Up With That (WUWT) only days to expose this as being, again, no more than the product of a tricksy computer model.
Now, a year ahead of the IPCC’s next major report, Nature has again provoked controversy with an article, by Jeremy Shakun et al, claiming to disprove what has long been seen as one of the most awkward facts for warmist theory. This is the evidence of ice cores which shows that, for millennia, rising levels of carbon dioxide have not preceded rising temperatures but have followed them, as warming releases more CO2 from the mighty carbon sink of the oceans.
As can be seen in full on WUWT, one of its expert contributors, Willis Eschenbach, has now carefully plotted all Shakun’s data, to show how it does not confirm his headline thesis at all. Even the Nature article admits that, when the earth was emerging from the last ice age some 15,000 years ago, it was temperatures that rose first, later followed by rises in CO2. But when Eschenbach downloaded all the CO2 data he could find, he came up with a startling discovery. Shakun had only used one CO2 data source – and he had mysteriously cut off his graph about 6,000 years ago.
When the additional data was fed in, it clearly showed CO2 continuing to rise after this point, for thousands of years, at the same time as temperatures went into a long decline. So once more the theory that a rising level of CO2 automatically leads to a warmer world – the central assumption on which the orthodoxy rests – has been demonstrated to be seriously awry.
As the respected US scientist Judith Curry put it last week, talking about another seemingly flawed paper published by the same journal: “Nature seems to be looking for headlines rather than promoting good science.” It could serve as an epitaph for the way that journal has been promoting this cause for 20 years. Whether, on the basis of so many curious manipulations of data, we should be happy to pay the biggest bill in history is another matter.