Monday, March 12, 2012

2413.txt

cc: "Brohan, Philip" <philip.brohanatXYZxyzoffice.gov.uk>
date: Mon, 21 Feb 2005 22:53:31 +0000
from: "Tett, Simon" <simon.tettatXYZxyzoffice.gov.uk>
subject: FW: More on the "Hocky Stick"
to: Keith Briffa <k.briffaatXYZxyz.ac.uk>, Hans.von.StorchatXYZxyzs.de, "Folland, Chris" <chris.follandatXYZxyzoffice.gov.uk>

Keith/Hans/Chris,
Defra do ask the impossible! Can you help me?

Are there other papers I should be aware of? Hans/Chris are the
statistical criticisms of Mackintyre and McKitrick OK?

Philip -- do you have any thoughts? [Beyond that the paleo community
cannot do stats!]

(Keith/Hans we can claim to the EU that SOAP is informing policy now!)

Simon

Dr Simon Tett Managing Scientist, Data development and applications.
Met Office Hadley Centre (Reading Unit)
Meteorology Building, University of Reading Reading RG6 6BB
Tel: +44 (0)118 378 5614 Fax +44 (0)118 378 5615
Mobex: +44-(0)1392 886886
E-mail: simon.tettatXYZxyzoffice.gov.uk http://www.metoffice.gov.uk
Global climate data sets are available from http://www.hadobs.org


-----Original Message-----
From: Johnson, Cathy (GA) [mailto:Cathy.JohnsonatXYZxyzra.gsi.gov.uk]
Sent: 21 February 2005 14:16
To: 'Simon Tett'
Cc: Warrilow, David (GA); Oliver, Sophia (GA); 'Vicky Pope'
Subject: RE: More on the "Hocky Stick"


Dear Simon
Thank you for bringing this to our attention. As there have been a
number of developments in this area lately, we would find it very useful
to have a short briefing note (1 page maximum) summarising the present
state of knowledge. Please can you prepare one for us?

It should cover:
Mackintyre and McKitrick's criticism of Mann et al (from a year or two
ago) von Storch et al's critique of Mann et al
Mackintyre and McKitrick's latest criticism of Mann et al
the new paper from Moberg et al
anything else you think we should be aware of
a summing up

many thanks
Cathy

-----Original Message-----
From: Simon Tett [mailto:simon.tettatXYZxyzoffice.gov.uk]
Sent: Wednesday, February 09, 2005 1:19 PM
To: Johnson, Cathy (GA)
Cc: Vicky Pope; Tim Osborn; Keith Briffa; Chris Folland; Simon Tett
Subject: More on the "Hocky Stick"


Cathy,
Tomorrow Nature is publishing a paper, by Moberg and others,
called "Highly variable Northern Hemisphere temperatures reconstructed
from
low- and high-resolution proxy data". It reconstructs past temperature
variability from 200 AD to present and finds much higher variability
than is in the Mann "Hocky Stick". They claim that temperatures around
1000 to 1100 are roughly the same as the 20th century prior to 1990.

Moberg et al combine data from low temporal resolution proxies (Ice
cores, ocean sediments and others) with high-resolution proxies (mainly
tree-ring data). Tree rings have problems estimating low-frequency
temperature variability due to the need to correct for tree growth. So
they time-filter the tree-ring data to remove low frequencies and
combine this with the low frequency variability.

However, Tim Osborn and Keith Briffa (who know much much more than I do
about proxy reconstructions) have grave reservations about the paper's
methodology. Their main concern is how the low-resolution data was
calibrated in order to convert changes in the proxy to changes in
temperature. The supplementary information to the paper (which is not
available to us right now) may reassure them (or may reinforce their
views).

yours

Simon

P.S. If you want to discuss more then I am in Exeter today/Thursday and
can be contacted on 01392 886886
--
Simon Tett <simon.tettatXYZxyzoffice.com>


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