hacker pubblicano mail di scienziati: dubbi sul cambiamento climatico?

Dall'Economist.

IS GLOBAL warming a trick? That is what some saw in a huge batch of e-mails and documents taken from the servers of the Climate Research Unit (CRU) at the University of East Anglia, in England, and put up anonymously on the web. The result has been a field day for those sceptical of the idea of man-made climate change, who have combed through them, pouncing and pronouncing on snippets that seem to show scientific malfeasance.

The CRU specialises in studies of climates past. For parts of the past where there were no thermometers to consult, such studies use proxy data, such as tree rings. Reconstructions based on these tend to show that the planet’s temperature has risen over the 20th century to heights unprecedented for centuries and perhaps millennia. They are far from the only evidence for believing in climate change as a man-made problem, but they are important, and the sharp uptick they show has taken on iconic value. A tree-ring reconstruction known as the “hockey stick”, which shows unprecedented 20th-century warming, has been a particular target of criticism by sceptics. It was published in 1998 by Michael Mann (then at Yale, now at Pennsylvania State University) and his colleagues, and featured prominently in the 2001 report of the Intergovernmental Panel on Climate Change (IPCC).

Hence the eagerness with which bloggers fell on one of the stolen e-mails, sent in 1999 by Phil Jones, the CRU’s director: “I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith’s to hide the decline.” Trickery associated with Dr Mann was catnip to the sceptics. But Dr Jones has clarified that “The word trick was used here colloquially as in a clever thing to do. It is ludicrous to suggest that it refers to anything untoward.” The “hiding” concerned the decision to leave out a set of tree-ring-growth data that had stopped reflecting local temperature changes. That alteration in growth pattern is strange, and unexplained, but eliminating it is not sinister.

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