Thursday, April 22, 2010

oaks "useless as a temperature proxy" yet used in Mann's temperature reconstruction

COMMENT: New Scientist report that "A leading British university has been told it must release data on tree rings dating back more than 7000 years to an amateur climate analyst and climate sceptic - Doug KeenanThe decision has been covered by the Times, and the Guardian.

From the New Scientist story: "Keenan says he believes the Irish data could bolster the sceptics' case that a thousand years ago there was a widespread medieval warm period on Earth not unlike current warming. But last year Baillie and his colleague Ana Garcia-Su√°rez published a study showing that Irish oak growth rings are a good proxy for summer rainfall, but not for temperature.

From the Times article  "Dr Rob Wilson, who runs the University of St Andrews tree ring laboratory, agreed that oaks were virtually useless as a temperature proxy, but said that scientists must now be vigilant about making data available."

Climate Audit's Steve McIntyre however indicates in his post Mann of Oak "Notwithstanding the considered opinion of Baillie and Wilson that oaks are “virtually useless as a temperature proxy” and “dangerous” to use in a temperature reconstruction, no fewer than 119 oak chronologies were used in  Mann et al 2008. Among Mann’s oak chronologies were three Baillie chronologies"

We have requested ABC provide some coverage and wonder what angle they take. Will they cover Steve McIntyre's pertinent observations?


  1. It's a bit odd that McIntyre is making a big deal of Mann et al. using this data if this data may appear to magnify the Medieval Warm period. Surely he should be upset if Mann left it out? See here: in case you didn't actually read the New Scientist story.

  2. The onus should be on Mann to explain why he included them.


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