Longe de ser considerada uma revista verde, "The Economist" é possivelmente a revista liberal mais respeitada a nível internacional. Este excelente artigo, na sua secção de ciência e tecnologia, é equidistante e equilibrado. Uma atempada análise do que está em jogo.
Nov 26th 2009
From The Economist print edition
Leaked e-mails do not show climate scientists at their best
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.
Another e-mail seen as shocking was from Kevin Trenberth of America’s National Centre for Atmospheric Research, in Colorado: “Where the heck is global warming? We are asking that here in Boulder where we have broken records the past two days for the coldest days on record.” But to take this as evidence that Dr Trenberth questions global warming seems foolish. He does not mean that a comparative lack of warming over the past decade shows greenhouse warming has stopped. He knows that the climate has natural ups and downs imposed on such trends, and that cold snaps happen. He is expressing frustration that the monitoring needed to understand how these variations work is not as good as it could be.
There is nothing in the e-mails so far to suggest that the authors do not believe in man-made global warming and are making the whole thing up, as some have been claiming. A more serious concern is that they believe in global warming too much, and that their commitment to the cause leads them to tolerate poor scientific practice, to close themselves off from criticism, and to deny reasonable requests for data.
More heat than light
Some e-mails suggest the criticisms made by sceptics outside academic climate science may have had more support within it than might be expected. Comments on the tree-ring section of the IPCC’s latest report by John Mitchell, director of climate science at Britain’s Met Office, raise issues very like those highlighted by perhaps the most prominent critic of the hockey stick, Steve McIntyre, who runs a blog called Climate Audit. An e-mail apparently from Dr Mann refers to an aspect of some statistical testing he did not want discussed widely as “dirty laundry”. Those worried that undue weight is being put on data from the tree rings of a dozen larches on the Yamal peninsula in Siberia, a topic that exercises Mr McIntyre, will be interested to see that some climate scientists shared some of their worries.
None of this is evidence of fraud. Looked at broadly, the e-mails seem to show a pretty workaday picture of scientists, with frustrations and sloppinesses, disagreements, opponents badmouthed, and cultural differences bridged (for example, explaining to an American colleague not just why a particular person is a prat, but what a prat is in the first place). Some of the e-mails may, looked at in a context not currently available (those posted were a selection), add weight to previous criticisms by Mr McIntyre and others. But that, in itself, is not dramatic. Many of these issues were aired in the most recent IPCC report, though not particularly thoroughly. And the idea of anthropogenic climate change rests on a great deal more than just tree-ring records, useful as they are for providing context to the current warming.
A spate of recent claims of global cooling, for example, rely on comparing 1998, the second-hottest year in the modern record (going to 1880), with 2008, which was relatively cooler. Yet, according to the Goddard Institute for Space Studies, a part of NASA, America’s space agency, 2008 was the ninth-hottest year on record. 2009 is shaping up to be the sixth-hottest. All of the ten hottest years recorded have come since 1997. And retreating Arctic sea ice provides even more visible data to support conclusions of warming.
More worrying than anything revealed about the scientific and other views of the people involved is the sense that legitimate attempts at ensuring transparency are being thwarted. Perhaps the most damaging exchange follows a request made by Dave Holland, a British sceptic, to see CRU e-mails under Britain’s Freedom of Information Act. (The CRU is publicly funded, and therefore subject to the act.) Caspar Amman, one of Dr Trenberth’s colleagues at the National Centre for Atmospheric Research, wrote of the request: “Oh MAN! When will this crap ever end??” Then Dr Jones wrote to Dr Mann: “Mike, can you delete any e-mails you may have with Keith [Briffa] re AR4? Keith will do likewise.”“AR4” refers to one of the IPCC’s reports. Dr Mann says he never deleted any e-mails. Gavin Schmidt, a scientist at NASA and the keeper of realclimate.org, an anti-sceptic blog, wrote that that e-mail was very ill-advised. Dr Jones did not answer a request for comment.
Dr Mann rebuts allegations of data-hoarding. Ten-year-old data protocols did not require keeping every scrap of data and calculation. Referring to his hockey-stick paper, he says: “If we knew then the type of scrutiny that would be applied to this work, we’d have made every scrap of data available.” Now, he says, climate scientists release not only all their data but also the proprietary algorithms they write to crunch the data. Not that he thinks it will help: “They’re not looking to reproduce your analysis, in many cases. They’re looking to badger, and to make unpleasant for us what we love doing as scientists. It’s obvious to other graduate students and post-docs rising up: if you choose to do this, this is what you will be subject to.”
He should not expect matters to improve any time soon. In the wake of “climategate”, the Competitive Enterprise Institute, a right-wing think-tank in Washington, DC, announced that it intended to sue NASA for not providing climate data and other materials requested under America’s Freedom of Information Act.
Many who accept that mankind is changing the climate disagree on how much and how quickly things will change—projections into the future rely on models whose feedback loops are constantly being refined, and which are the source of much debate. Other observers have written that the focus on carbon dioxide above all else has been misplaced, since quick wins are available in other areas like cutting methane emissions or black carbon soot.
Sadly, discussing these things rationally in public is hard. As Judith Curry, a climatologist at the Georgia Institute of Technology, observes, attacks on climate scientists, sometimes paid for by carbon-emitting industries when global warming first became a public issue, have made many researchers in the field nervous and defensive. This does not excuse attempts to resist transparency, but does help explain them. Though such attacks have become rarer, there is now little presumption of good faith between global warming believers and sceptics, even independent ones, as an episode like this illustrates. Little wonder that the scientists are looking tribal and jumpy, and that sceptics have leapt so eagerly on such tiny scraps as proof of a conspiracy.