cc: "Brohan, Philip" date: Mon, 21 Feb 2005 22:53:31 +0000 from: "Tett, Simon" subject: FW: More on the "Hocky Stick" to: Keith Briffa , Hans.von.Storch@gkss.de, "Folland, Chris" 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.tett@metoffice.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.Johnson@defra.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.tett@metoffice.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 Department for Environment, Food and Rural Affairs (Defra) This email and any attachments is intended for the named recipient only. If you have received it in error you have no authority to use, disclose, store or copy any of its contents and you should destroy it and inform the sender. Whilst this email and associated attachments will have been checked for known viruses whilst within Defra systems we can accept no responsibility once it has left our systems. Communications on Defra's computer systems may be monitored and/or recorded to secure the effective operation of the system and for other lawful purposes. The original of this email was scanned for viruses by the Government Secure Intranet (GSi) virus scanning service supplied exclusively by Energis in partnership with MessageLabs. On leaving the GSi this email was certified virus-free