Richard Muller appoints himself 'hide the decline' expert without actually reading the email
The most cited "Climategate" email is one from Phil Jones discussing a graph he produced for a WMO report, where he discusses "Mike's trick" and "hide the decline". A number of misconceptions have arisen concerning this email. Unfortunately one of the leading producers of misinformation at the moment is Professor Richard Muller from Berkeley. Muller's main error is confusing a number of separate issues, blurring them into a single "hide the decline" technique. Muller commits this error in a public lecture (emphasis added):
"A quote came out of the emails, these leaked emails, that said "let's use Mike's trick to hide the decline". That's the words, "let's use Mike's trick to hide the decline". Mike is Michael Mann, said "hey, trick just means mathematical trick. That's all." My response is I'm not worried about the word trick. I'm worried about the decline."
Muller uses the phrase "Mike's nature trick to hide the decline" as if its Phil Jones's actual words. In a lecture recorded last weekend at Berkeley, Muller continues to expound on how Michael Mann's trick was used to hide the decline (emphasis added):
"What they said is "how can we hide the decline?" And the suggestion came back from Phil Jones at the UK, "Let's use Mike's trick to hide the decline". Mike's trick consisted of erasing that data, calling it unreliable, and then substituting the temperature data from thereon."
However, the original text from Phil Jone's email indicates otherwise:
"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."
It's clear that "Mike's Nature trick" is quite separate to Keith Briffa's "hide the decline". Somehow Muller has cherry picked different sections of Phil Jone's emails and morphed them into a single phrase, "Mike's nature trick to hide the decline". This is particularly ironic as Muller decries the use of cherry picking throughout his lectures.
What is "Mike's Nature trick"?
This refers to a technique (in other words, "trick of the trade") used in a paper published in the journal Nature by lead author Michael Mann (Mann et al 1998). The "trick" is the technique of plotting recent instrumental data along with the reconstructed data. This places recent global warming trends in the context of temperature changes over longer time scales.
Mann's 1998 paper in Nature plotted temperature back to 1400 AD. The temperature reconstruction was extended back to 1000 AD and published in Mann et al 1999 which was reproduced in the IPCC Third Assessment Report, shown below:
Figure 3: Northern Hemisphere mean temperature anomaly in °C (Mann et al 1999).
There is nothing secret about "Mike's trick". Both the instrumental (red) and reconstructed temperature (blue) are clearly labelled in Mann's 1998 Nature article, the follow-up Mann et al 1999 and the IPCC Third Assessment Report. Contrary to Muller's assertion, there is no "decline" in Mann's reconstructions. The source of "the decline" come from tree-ring density proxies at high latitudes (Briffa 1998). There are very few of these in Mann's proxy data and hence his reconstructions never required removal of any declining proxies.
One only has to read Phil Jone's original email to understand that Mike's trick has nothing to do with Briffa's "decline". And when one takes the time to understand Michael Mann's work in Mann et al 1998 and Mann et al 1999, it's clear that there is no "decline" in Michael Mann's work whatsoever. Ironically, at the beginning of his lecture, Muller laments:
"There's no subject I've ever worked in in which there is so much misinformation."
Sadly, due to a lack of rigour in investigating the science, Muller is further contributing to the sea of climate misinformation.
Note: in an upcoming post, we'll see how Muller continues to provide misinformation by failing to distinguish between Phil Jones and Keith Briffa over released data.