Muller Misinformation #2: 'leaked' tree-ring data

We recently examined misinformation from Professor Richard Muller where he confused "Mike's trick" with "hide the decline". This is a habitual error from Muller where he fails to distinguish between the hockey stick by Michael Mann and the decline in tree-ring density by Keith Briffa. Despite this error being pointed out to him, he repeated the error in a recent NPR interview:

"Luis Alvarez taught me the fundamental scientific rule, which is you've got to show everybody your dirty laundry...My problem with the way the hockey stick was derived was that there was none of this...if you hide something...the person you are most likely to fool is yourself."

For some reason, Muller has it in his mind that there was hidden decline data in Michael Mann's hockey stick (Mann et al 1998). However, there was no hidden tree-ring density data - the tree-ring density data is in a completely different work from Briffa 2000. One wonders how long Professor Muller will continue to repeat this misinformation.

Nevertheless, we now move onto further misinformation provided by Professor Muller where he claimed the "decline" data was withheld from the public until it was "leaked" at Climategate. In a recent lecture, Muller claims:

“In their paper, if you dig into it, they say they did some things with the data from 1961 onwards - they removed it and replaced it with temperature data. So some of the people who read this paper asked to see the data, they refused to send it to them, the original raw data. They used the FOI act. The FOI act officer on the advice of the scientist would not release the data. Then the data came out. They weren't hacked like a lot of people say. Most people who know this business believe they were leaked by one of the members of the team who was really upset with them.”

Muller continues to expound on this in the NPR interview:

"I think that Climategate is a very unfortunate thing that happened, that the scientists who were involved in that, from what I've read, didn't trust the public, didn't even trust the scientific public. They were not showing the discordant data. That's something that - as a scientist I was trained you always have to show the negative data, the data that disagrees with you, and then make the case that your case is stronger. And they were hiding the data, and a whole discussion of suppressing publications, I thought, was really unfortunate."

As discussed in Muller Misinformation #1, the "decline" refers to a decline in tree-ring density at certain high latitudes. The data indicating a decline in tree-ring density comes from Briffa 2000. The original tree-ring density data is shown below with the green line represents tree-ring density and the thick black line showing the instrumental temperature record.

Briffa tree-ring density

Figure 1: An indication of growing season temperature changes across the whole of the northern boreal forest. The LFD curve indicates low-frequency density changes. Note the recent disparity in density and measured temperatures (Briffa 2000).

Muller claims that Briffa's data was withheld from the public until it was "leaked" in late 2009 at the time of "Climategate". This is untrue. The Briffa 2000 data was already freely available via the Climatic Research Unit (CRU) website. This had been online since late 2008, as documented by Steve McIntyre.

What about the "original raw data" that Muller claims was refused to the public?  The original raw data for the tree-ring density comes from the "Schweingruber" network, consisting of 387 chronologies from across the northern hemisphere. This data was also freely available online via the CRU website. This link was given to Steve McIntyre in October 2008 in response to a Freedom of Information request to CRU, as seen in this lengthy document of FOI requests made to CRU (FOI 08-50 on page 169).

As for Muller's assertion that Climategate was leaked (clarifying that it was emails taken from the server, not data), the fact that the Climategate hackers also hacked the Real Climate server and uploaded the emails onto their website would indicate an external hacker rather than a CRU whistleblower. Nevertheless, there are scant details on the culprit given a criminal investigation is still ongoing. Muller make claims of an internal leak while providing no evidence.

The key point is that Briffa's data was not leaked during "Climategate". Professor Muller's assertion that the post-1960 "decline" data was not made available until Climategate is incorrect. It is unfortunate that Muller continues to repeat a narrative on Climategate that is provably at odds with the actual history, when he is otherwise well-positioned to take a leadership role in resolving issues concerning climate trends

Posted by John Cook on Friday, 15 April, 2011

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