| From | Jonathan T. Overpeck | Date | Mon, 10 Jan 2005 14:40:27 -0700 |
|---|---|---|---|
| To | Eystein Jansen | ||
| CC | Keith Briffa, cddhr@giss.nasa.gov, Stefan Rahmstorf, Fortunat Joos | ||
| Subject | Re: [Wg1-ar4-ch06] comments to 6.3.2.1 (mainly for Keith) | ||
I agree; Keith should have the room, and section 6.5.8 should be compatible - has Fortunat followed the discussion between David/Stefan. Can you guys (David, Stefan, Keith, and Fortunat) ensure this? Thanks, Peck >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 >>>>> >>>>>www.realclimate.org >>>>>_______________________________________________ >>>>>Wg1-ar4-ch06 mailing list >>>>>Wg1-ar4-ch06@joss.ucar.edu >>>>>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 >>>> >>>>http://www.cru.uea.ac.uk/cru/people/briffa/ >>>>_______________________________________________ >>>>Wg1-ar4-ch06 mailing list >>>>Wg1-ar4-ch06@joss.ucar.edu >>>>http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06 >>>_______________________________________________ >>>Wg1-ar4-ch06 mailing list >>>Wg1-ar4-ch06@joss.ucar.edu >>>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 >> >>http://www.cru.uea.ac.uk/cru/people/briffa/ >>_______________________________________________ >>Wg1-ar4-ch06 mailing list >>Wg1-ar4-ch06@joss.ucar.edu >>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: www.bjerknes.uib.no/mcts >---------------------------------------------------------------------------- > >_______________________________________________ >Wg1-ar4-ch06 mailing list >Wg1-ar4-ch06@joss.ucar.edu >http://www.joss.ucar.edu/mailman/listinfo/wg1-ar4-ch06 -- Jonathan T. Overpeck Director, Institute for the Study of Planet Earth Professor, Department of Geosciences Professor, Department of Atmospheric Sciences Mail and Fedex Address: Institute for the Study of Planet Earth 715 N. Park Ave. 2nd Floor University of Arizona Tucson, AZ 85721 direct tel: +1 520 622-9065 fax: +1 520 792-8795 http://www.geo.arizona.edu/ http://www.ispe.arizona.edu/ | |||