Claim: Climate scientist Michael Mann (of Penn State University) is guilty of misusing confidential data, engaged in a conspiracy to withhold information, and manipulated or destroyed data to strengthen his case that human activity was changing the global climate.

Why this claim is wrong: Michael Mann is principal author of the famous 1998 paper which first showed the "hockey stick" graph of global temperature for the past one thousand years, ending in the upward "hockey blade" spike during the fossil fuel age. This was a centerpiece in Al Gore's "An Inconvenient Truth" and if a picture is worth a thousand words, this certainly qualifies. It is natural that AGW denialists would go after the author of this work. These charges against Michael Mann are serious, enough to terminate a career if found true. One would hope the AGW denialists had evidence before making and distributing to the press such charges. In fact, the slander revolves around the meaning of the word "trick", found in emails stolen by the AGW denialists ("Climategate"). Scientists and mathematicians often use the word "trick" to refer to a clever insight used to solve a difficult problem. Having hung around other scientists such as myself for 35 odd years, I can tell you this is absolutely true. Anyone who would base such serious slander on their own ignorance of the meaning of the word "trick" clearly has no experience in science or mathematics (or perhaps they knew exactly what it meant, but yet found this a great opportunity to advance their agenda by making such slanderous charges in front of policitians and science-ignorant students, media, and the public). The "trick to hide the decline", as climate denialists like to truncate it, refers to the decline in tree-ring-inferred temperatures. The reliability of tree rings as a temperature proxy is properly open to question in modern times. Why? Because all during the past thousand years except for the past 60 years or so, CO2 levels have been fairly constant. Do you suppose that CO2 concentrations might independently influence tree growth and tree rings? Do you suppose that rapidly rising CO2 levels that change climate rapidly might influence tree health and growth and that calibrations might be affected? Quite reasonable. Use your temperature proxies when you trust them, and when there's good reason to doubt them they should not be used; especially when you have actual temperatures so you don't need proxies. The calibration of the proxies was documented in Mann's and other papers which re-did this work.

Having on your faculty a prominent scientist guilty of fraud and other misconduct would be a huge liability, and so even if the charges had no basis or evidence, Penn State University conducted an inquiry - and Mann was cleared of any wrong doing or bias. Here's the NY Times article on the inquiry and Mann's vindication, with embedded links. Note also that climate denialist blogs charged him with witholding data and hiding or destroying data. This inquiry and a dozen others found NO BASIS for this charge. All data and codes legally able to be released were released at the time of his original paper. All data and codes subsequently were cleared by foreign countries to release, and have been released. It was those other countries whose data partially comprised the dataset analyzed. See this recent interview in "Discover" magazine. All relevant climate forcing data is available to anyone, here. Here is Mann's response to the political witch hunt against climate scientists, including himself. And a more recent response (Dec 2011) by Mann is here, and a more recent summary of these political attacks in a talk at the Chapman conference of the AGU in summer 2013, here.

I have personally heard these baseless charges against an honorable scientist made by a (thankfully now former) teacher at Cabrillo College. Anyone who would repeat such slanderous charges - worst of all, to students - as if they were fact, as late as 2009, when they clearly have no basis, let alone providing even a shred of evidence they are true... what can you say about their own bias, their own objectivity, their own committment to telling the Truth? Such people deserve our contempt.

Outrageous slanders against Michael Mann aside, how do the data-based criticisms of the "Hockey Stick" temperature plot stand up? Here's an excellent study showing re-analyses even assuming the (mostly invalid) criticisms of the 1999 analysis. Bottom line: no significant change - it's still a temperature "Hockey Stick".

Original temperature reconstruction from Mann & Bradley 1998, as published in the IPCC 2001 document

Reconstructions of Northern Hemisphere temperatures for the 2nd millennium according to various older articles (bluish lines), newer articles (reddish lines), and instrumental record (black line)

IPCC temperature reconstructions using proxy measures of various kinds, for the Northern Hemisphere only. The "medievel warm period" is only seen in the Northern Hemisphere data, not globally. The instrumental record goes back to the 1800's and is shown in black.

Jones and Mann (2004) temperature reconstructions using proxies, with global temperatures at the bottom pane. Actual instrumental temperatures shown in red. Proxies and instruments both agree - still a Hockey Stick

"Climategate" was a fabricated smear campaign against climate scientists, based on stolen emails from the private correspondence between climate scientists and timed to be released to the media shortly before the 2009 UN Copenhagen Climate Summit, no doubt to insure that no significant carbon taxes or other other carbon-limiting agreements would result. Denialists took naive or distorted meanings from out-of-context passages to appear to justify their charges to a gullible, scandal-hungry media that global warming was a scientific fraud. Numerous investigations showed there was no fraud, no bad science, and no lies. The real scandal is the behavior of AGW denialists who so easily slander the work and character of good scientists in the name of preserving "business as usual" corporate profits. The status of this attack on climate scientists is well linked and summarized (as of 2011) here. All this, as if the "Hockey Stick" was the principle reason for the IPCC conclusion that global warming was human-caused, which it is not. Stanford climatologist Stephen Schneider points out (32 minutes into this lecture) that he repeatedly told the media that the IPCC's 2007 conclusion that global warming was human-caused was not at all based on the "hockey stick", but instead on the many "fingerprints" (observational patterns in global warming which can only be produced by greenhouse gases), and not once would the media actually print this fact.

Ponder this - the hackers who broke into the servers and stole email correspondences between climate scientists to spawn "Climategate" - they stole THOUSANDS of emails. Their goal was to publish and promote the most damaging material they could find. And THIS trumped up play on words is the best they could do. What does that say to any reasonable observer?

Update Aug 31 2013: Scientists are now adjusting to the reality of the outrageous treatment they and their work are receiving. This is a corportate/political environment they have not been trained for, nor are they skilled at responding to (yet). Having their work understood is vital to the future. They are fighting back, and I applaud this. Michael Mann has filed charges of slander against the right-wing National Review in their comparison of him with sex-offender Jerry Sandusky (both at Penn State U), and the judge has just decreed that the charges have merit and are likely to succeed in court where they are next to be heard. One can only hope that this will have a chilling effect on the Big Oil sponsored attacks.

Update Jan 2014: Mann, was further slandered by the Competitive Enterprise Institute , the National Review, and right-winger Rand Simberg in the media, claiming "scientific fraud" (but no evidence to back it up). This was too much, and Mann filed a defamation suit against these defendants. The suit has been judged to have merit by the presiding judge, and will go forward. So far, it looks bad for the right wing National Review and others involved in this intimidation against science.

In Short: No raw data was ever hidden. Some data based outside the U.S. was kept proprietary at the insistence of the government of the relevant weather data sites, until formal publication, a fact never hidden. All raw data is public and available to anyone. The "decline" was in tree ring data during the modern era when temperature proxies are not needed; tree ring - derived temperatures which properly should be questioned given that CO2 levels can be expected to substantially affect tree growth. Several independent investigations, after these baseless false claims, showed there was no data tampering, no fraud, no bad science, and the results stand. These intimidations are, unfortunately, a standard part of denialist tactics. And out of thousands of emails, THIS nonsense was the most damaging material they could find to try to twist to their purposes!



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