date: Wed, 16 Apr 2003 21:05:09 +0100 from: "Max Beran" subject: RE: The Alexander technique to: "Keith Briffa" Keith Yes but what about the substantive dendro queries. Max -----Original Message----- From: Keith Briffa [mailto:k.briffa@uea.ac.uk] Sent: 16 April 2003 10:10 To: Max Beran Subject: The Alexander technique Dear Max nice to hear from you and thanks for taking the trouble to get in touch with that advice. It so happens that I am booked for a session sponsored by the University in June , and ironically my wife Sarah , on reading a book someone else lent me with the same advice, has become a devotee. I have still to read it! I am having physio once a fortnight , but I have to say I am a little disappointed that I am being to get more frequent back aches and some pain again , particularly when I sit for a while. Anyway , I will go to that course and perhaps even find time to read the book. Thanks again Keith At 03:03 AM 4/16/03 +0100, you wrote: >Keith > >Did you have an opportunity to ponder the following. > >I hope your back is fully mended. You ought to take up the Alexander >technique. I mention it because my wife is an Alexander technique teacher >and our principal breadwinner now that I'm retired. > >All the best > >Max > >-----Original Message----- >From: Max Beran [mailto:maxberan@oldboot.demon.co.uk] >Sent: 25 February 2003 15:10 >To: k.briffa@uea.ac.uk >Subject: Tree rings and the Mann hockey stick > > >Dear Keith > >I deliver courses on global change in Oxford and area and one of the matters >that comes up is the Mann hockey stick and its implications (Mann-made >climate change:-). It has been given enormous prominence both in terms of >its message about the recent and "deep" past, and in terms of its portents. >Its use as the take-home message from the policymakers summary of the >IPCC-TAR demonstrates this clearly. > >I am aware that the detailed form of the curve conflicts with what is known >about well attested features of the millennial climate (weak, if any, >signatures of medieval warming and the little ice age), but what is >exercising me more is what it says about trees themselves (I know it is >multi-proxy but as I understand it, dendrochronology rules). > >That tree-ring contribution to the temperature reconstruction obviously uses >a numerical expression of the sensitivity between temperature and tree ring >width/density. I don't have any numbers but if these are anything like the >ones you show in Figure 2 of your 1998 Nature paper, then there is an >approximate one-to-one between the standardised departures of >April-September temperature and tree ring width or density. > >Two areas of concern are (a) the situation up to the present, and (b) the >future. > > The present > >Given that the standard deviation of the yearly values of summer average >temperature is of the order of 0.5 degree, this is coincidentally about the >same difference as between pre-industrial times and now. This implies that >there ought to have been a similar one standard deviation growth in tree >rings. (Again I've no access to real numbers but I guess we are talking a mm >or 3). At an individual site and year this is doubtless well within the >noise level, but would be expected to shine through when maintained over a >number of years and sites. I tried to compare this with Figure 7 of your >1998 Royal Society paper but got mixed up with whether this shows the annual >values of the BAI (as implied by the text) or the annual values of the >year-on-year "change-in-BAI" as in the caption. If the former, one might >have expected some sort of compound interest pattern, if the latter an even >faster growing pattern (compound compound). Perhaps the modesty of the rise >is indicative of the reversal of the sensitivity between tree rings and >temperature that is visible in the post-1940 data on Figure 6 of the Royal >Society paper. > >How do you reconcile this reversal in the sign of the relationship between >tree growth and temperature, and Figure 6 in general, with the statements >elsewhere in the paper saying there has been a non-climatic "enhancement" of >tree growth? > >If there has indeed been a reversal in the sign of the sensitivity this >would imply a very large reduction in NPP as a result of the conspiracy >between ring width and wood density. One might then ask why this post-1940 >sensitivity is not a more reliable basis for backward reconstruction? I know >you tend towards non-climatic explanations (notwithstanding my confusion >over the direction) but for my money this explanation could be at least as >legitimately aimed at the period from 1880 to 1940. Huge proportional >changes in land use and industrial pollution in that era make current >incursions look relatively speaking benign. Just look at population, >agricultural area, industrial outputs and emissions data to see this. > > The future >The climate models, bless'em, indicate a temperature increase of the order >of less than 5 to more than 10 standard deviations by the 2080s. Accepting >the robustness of the sensitivities implicit in the Hockey stick >reconstruction (much used to tune and confirm GCM behaviour), that suggests >to me that we can anticipate a similar order of growth in tree ring width >and density? I can't picture what the standard deviation of the density >series might be in relation to the mean, but I would hazard a guess that >applying this to the tree ring width alone would lead to a more than >doubling of today's BAI. The overall effect on NPP of such a dramatic shift >in growth behaviour would surely turn the current 60-ish Gt to well over 100 >Gt. If only a modest fraction was turned into NBU this could make a mighty >hole in emissions and would be good news at least over the lifetimes of the >trees. And all this is would put the benefit of CO2 fertilisation completely >in the shade. > >Seems to me we have a classic checks-and-balances situation here. The >climate modellers (and the policy makers) implicitly accept the tree-ring to >climate sensitivity as far as the past is concerned. This bolsters their >belief in the forward projections of temperature with all that that implies >for impacts and policy. By their own logic, they should then also accept >that trees (far and away the dominant living carbon pool) would continue in >their positive temperature-driven response and provide a hefty negative >feedback acting via the land carbon cycle. In all seriousness though, does >anyone really believe trees would respond so dramatically. We'd know about >it from physiology and see some signal in latitude clines - as far as I know >they don't exist, but you'd know for sure. > >So at what point does the tree ring to temperature sensitivity break down? >And what might its impacts be on the hockey stick and through that the GCM >tuning? Have there been other periods when your post-1940 reversal occurred >perhaps due to macroclimatic forces? Could these also account for the >discrepancy between the hockey stick and what we thought we used to know >about the climate since 1000 AD? > >Any thoughts on any of the above would be delightedly received. You may even >save a soul from falling into the embrace of the sainted Lomborg! > >Max Beran > >1 The Croft >East Hagbourne >Didcot OX11 9LS >Tel: 01235 812493 >Fax: 0870 054 7384 -- 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/