| Details1: | Phil Jones antwortet David R. Legates "Breaking the “Hockey Stick” "
To: Timo Hämeranta (timo.hameranta@pp.inet.fi)
From: Phil Jones
Subject: Re: The broken "Hockey Stick"
Dear Timo,
I can fully understand why Mike Mann doesn't have email contact with you. I have read
David Legates' piece on the NCPA web site and there is so much wrong with it, I don't know
whether I should attempt to respond. I will, but I'll be brief. I don't want it to seem like
nitpicking, but David should get his facts right. He should have read the papers properly and
noted their dates and years. He should put up an apology and he should back up his text
with some facts/details and not just statements saying the record is unreliable and can't
be reproduced. I will go through a few points and will not respond any more unless David issues
an apology.
Surely, if you want people to believe your point of view you should get the facts right.
Keynes changed his opinion when the facts changed, but I'm sure he first checked that
the facts were right !
1. The Figure is from the IPCC Report of 2001. Fact.
2. The GRL paper by Mann and Jones was written in 2003. Fact
3. The GRL paper was not an update of what IPCC reported, nor was it an update of what
IPCC used in 2001 (namely the Mann et al papers in 1998/1999). Fact
4. The GRL paper had a clearly different intention as stated in the paper. Fact
5. So, the curve from the GRL 2003 paper was not used in the 2001 IPCC report. Fact - it
couldn't have been.
6. The McIntyre and McKittrick paper in 2003 in Energy and Environment didn't contend
that Mann and Jones unjustifiably truncated and extrapolated trends or data. Fact - it
couldn't have because it was printed before the Mann and Jones 2003 paper in GRL
came out.
7. The Mann and Jones 2003 paper didn't unjustifiably truncate or extrapolate trends or data
in any of the series used. Fact - I have all the series.
8. The Mann and Jones 2003 paper uses series from 2 ice boreholes in Greenland. Fact - we
digitized the series from the original papers.
9. Land borehole data are not used in Mann and Jones 2003. Fact - we stated in the paper we
wanted to only use series that correlate with instrumental records. If someone can tell
me how to correlate a series with two values (one for 2000 and one for 1900) then please
do. The 2003 paper's aim was to develop an annual-timescale series. Borehole series are
not amenable for this. There is a paper by Huang (2004) in a recent GRL where a
combination is attempted, but an assumption is made that boreholes give one timescale,
conventional another.
10. Esper et al (2004) argue that our tree-ring series are over standardised and have lost
low frequency. The techniques Esper et al use were developed here at CRU (by my colleague
Keith Briffa). Fact - Jan Esper often seems to forget this. If you note the series Mann and
Jones (2003) use, you will see we were very careful with standardization. All the discussion
about trees and the loss of low-frequency variation began in CRU. Fact.
11. None of the series we use are based on too few trees. A more relevant fact is that many
of Esper et al are in the earliest years. It is necessary to go back and read the papers,
back to the first in the early 1990s.
12. We do not correlate temperature trends with tree age. Fact - this just shows how ridiculous
some of the sentences in the Legates' piece are. Why would we want to do this.
13. The borehole retraction by Mann and Rutherford is about 0.1 deg C. Fact - read the
retraction.
14. The trend over the 20th century in the Figure and in the instrumental data. IPCC quotes
0.6 deg C over the 1901-2000 period. Fact - but Legates is eyeballing the curve to get
0.95 deg C. A figure isn't given in Mann and Jones (2003). Take it from me the trend is
about the same as the instrumental record.
15. The series in Mann and Jones (2003) is a simple average of all the constituent series. Fact.
Averaging is straightforward, we also experimented with various weights. I wouldn't call
averaging a statistical technique, but I suppose a weighted mean could be referred to as a
statistic. Throughout the whole piece though Legates appears to me be referring back to
Mann et al paper in 1998. I may be wrong here, and I apologize if I am. I only read
continued reference to Mann and Jones (2003).
16. Isn't it a good idea to base the use of proxy records on how they match instrumental
records ! Am I missing something here? When did anyone decide that proxy records
could be assumed to match something else? They are proxy records - past climate
proxies, in this case for temperature. If a record is a proxy for temperature, then to my
mind it should have some agreement with an instrumental record. This is a basic
fundamental of paleoclimatology.
17. The instrumental record has not been considered up to now - although you accepted the
IPCC warming of 0.6 deg C earlier. I could go into more detail here but won't as it is
another issue.
18. Mann and Jones (2003) had a method for estimating uncertainty back in time. When I say
we had a method, I mean we used numbers to estimate it. Legates says based on
his preliminary analysis it is twice as large - based on what? Clearly based on someone
who believed we were wrong to base our use of proxy records solely on how well they
matched instrumental temperature data !
19. Mann and Jones (2003) make no such claim that all change over the last 2000 years
occurred in the 20th century. Fact, we don't. We have stated in other articles that the
MWP and LIA are simplistic interpretations of the past and all paleoclimatologists
would be better referring to the past using calendar dates. If the widely accepted MWP
and LIA were as clear as Legates seems to think, why are paleoclimatologists
bothering to collect more data?
20. We do claim that the late-20th century is the warmest period of the millennium. Fact. We
also claim that the 1990s are the warmest decade and that 1998 is the warmest year. We
don't make those claims in the 2003 paper.
As I said at the beginning I could go into more detail. I have only done to put the record
straight, not to enter into any debate.
Regards
Phil
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