date: Wed Jun 15 15:54:12 2005 from: Keith Briffa subject: Fwd: Re: [Wg1-ar4-ch06] comments to 6.3.2.1 (mainly for Keith) to: Tim Osborn X-Sender: nglej@pop.uib.no Date: Mon, 10 Jan 2005 18:01:42 +0100 To: Keith Briffa , David Rind , wg1-ar4-ch06@joss.ucar.edu From: Eystein Jansen Subject: Re: [Wg1-ar4-ch06] comments to 6.3.2.1 (mainly for Keith) X-checked-clean: by exiscan on noralf X-Scanner: 86c2b4d1c5e6d442895e9f35c939dd37 [1]http://tjinfo.uib.no/virus.html X-UiB-SpamFlag: NO UIB: 0.0 hits, 11.0 required X-UEA-MailScanner-Information: Please contact the ISP for more information X-UEA-MailScanner: Found to be clean Hi, interesting discussion on an important topic. If space is the limiting factor we may have to evaluate whether to cut back on less central issues elswhere in the chapter. We will to a large extent be judged on how we tackle the hockey stick, sensitivity, unprecedented 20th century warming isuues in view of palaeo, and if a slight expansion is what it takes to do this properly, then I am sympathetic to that (without having heard Peck on the issue). Cheers, Eystein At 16:32 +0000 10-01-05, Keith Briffa wrote: thanks David have to say that it is very difficult to say much in the minimal space - and we really need a page to discuss the problems in the reconstruction and and interpretation of the various forcings in different models - I am just going to put this down in an over abbreviated way and ask for specific corrections for you and Stefan et al. The detail perhaps depends on what the final Figure looks like and Tim is trying to put it together but lots of weird and interesting stuff / questions arise as we do - especially relating to past estimates of solar irradiance used by different people. At 15:29 10/01/2005, David Rind wrote: (I tried to send this earlier and it got hung up; apologies if it eventually gets through and you get a second version.) Well, yes and no. If the mismatch between suggested forcing, model sensitivity, and suggested response for the LIA suggests the forcing is overestimated (in particular the solar forcing), then it makes an earlier warm period less likely, with little implication for future warming. If it suggests climate sensitivity is really much lower, then it says nothing about the earlier warm period (could still have been driven by solar forcing), but suggests future warming is overestimated. If however it implies the reconstructions are underestimating past climate changes, then it suggests the earlier warm period may well have been warmer than indicated (driven by variability, if nothing else) while suggesting future climate changes will be large. This is the essence of the problem. David At 9:28 AM +0000 1/10/05, Keith Briffa wrote: THanks Stefan At 21:13 07/01/2005, Stefan Rahmstorf wrote: Keith, some comments added in the text for the past millennium, plus I wrote some extra sentences on the implications of the dispute (repeated below). Hope it is useful, Stefan Note that the major differences between the proxy reconstructions and between the model simulations for the past millennium occur for the cool periods in the 17th-19th Centuries; none of these reconstructions or models suggests that there was a warmer period than the late 20th Century in the record. A larger amplitude of preindustrial natural climate variability does not imply a smaller anthropogenic contribution to 20th Century warming (which is estimated from 20th Century data, see Chapter XXX on attribution), nor does it imply a smaller sensitivity of climate to CO2, or a lesser projected warming for the future. -- Stefan Rahmstorf <[2]http://www.ozean-klima.de>[3]www.ozean-klima.de [4]www.realclimate.org _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu [5]http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06 -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [6]http://www.cru.uea.ac.uk/cru/people/briffa/ _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu [7]http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06 _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu [8]http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06 -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [9]http://www.cru.uea.ac.uk/cru/people/briffa/ _______________________________________________ Wg1-ar4-ch06 mailing list Wg1-ar4-ch06@joss.ucar.edu [10]http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06 -- ______________________________________________________________ Eystein Jansen Professor/Director Bjerknes Centre for Climate Research and Dep. of Earth Science, Univ. of Bergen Allégaten 55 N-5007 Bergen NORWAY e-mail: eystein.jansen@geo.uib.no Phone: +47-55-583491 - Home: +47-55-910661 Fax: +47-55-584330 ----------------------- The Bjerknes Training site offers 3-12 months fellowships to PhD students More info at: [11]www.bjerknes.uib.no/mcts ---------------------------------------------------------------------------- -- Professor Keith Briffa, Climatic Research Unit University of East Anglia Norwich, NR4 7TJ, U.K. Phone: +44-1603-593909 Fax: +44-1603-507784 [12]http://www.cru.uea.ac.uk/cru/people/briffa/