cc: grudd@natgeo.su.se date: Thu Apr 8 09:54:18 1999 from: Keith Briffa subject: Re: Subboreal/Subatlantic transition to: Bas van Geel Yes I would be interested and I think you should contact Hakan Grudd who is responsible for the Swedish Material and was responsible also for bridging the pine chronology gap in the 3rd century B.C. best wishes Keith At 02:20 PM 4/7/99 +0100, you wrote: >Dear Dr Briffa, >Since several years I am involved in studies about the value of delta 14C >as a climate proxy (see below for relevant papers). You may know that we >mainly concentrated on the Subboreal/Subatlantic transition >(archaeological, geological and other evidence for cooler, wetter climate >from the moment of sharp rise of delta 14C around 850 cal BC). >Two years ago more than 60 bog oaks were discovered at the site Diemen (at >4 km from my lab). I am involved in the peat research of that site. I also >compared the time ranges of individual trees with the delta 14C record. In >Diemen, like in the central European oak record and in the over-all Dutch >oak record there is a minimum (at Diemen even a hiatus and a change of >location of oak populations) in the representation of trees around 650 cal >BC. In first instance one is inclined not to see any correspondence with >the climate change starting around 850 cal BC. >HOWEVER, the representation curves of oaks that one usually sees >illustrated are 'number of trees deposited per (50) years (year of >deposition)' or 'number of individual samples of each year'. As a >biologist/ecologist I was more interested in the vulnerable phase of >reproduction of the trees. And then it appeared that a sharp >decline-of-successful-seedlings indeed corresponds with the start of the >sharp rise of delta 14C! So oaks apparently had recruitment problems after >the start of this climate change. The ca 650 cal BC decline in the above >mentioned oak chronology curves in fact has to do with a phenomenon >(reproduction problem) that took place already about one oak generation >earlier (our bog oaks live about 200 years). I know that the central >European oak chronology is mainly based on river oaks. So the temporary oak >problem seems to have been more general. Now I only can guess about the >cause: flowering or fruit setting reduced? rotting acorns? frost damage? >I know that the fennoscandian pine data also show a minimum in >representation of trees. Matti Eronen told me in December that he had just >over-bridged the hiatus in his Finnish record. >What I ask you is: are you interested to contribute as a co-author to the >paper that I have in mind: a summation of the overall >NW-European/C-European tree records per region (especially fluctuations of >successful seedlings) for the first milenium BC,in relation to the delta >14C record and corresponding evidence for climate change as mentioned in >the papers below? Of course we have also to think and write about the cause >and effect of the recorded phenomenon. >I think that we probably better can exclude the archaeological dendro-data >because this study is about the climatological/ecological conditions in the >first place. > >I have contacted (+: positive reaction received): >Esther Jansma + >Hans van der Plicht + >Ute Sass-Klaassen + >Markus Lindholm and Matti Eronen + >Mike Baillie + >Hubertus Leuschner >Andre Billamboz and Willy Tegel >Pentti Zetterberg + >Klaus Felix Kaiser >Marco Spurk + > >Please let me know if you are interested. >Best wishes, > >Bas van Geel > >----------------------------------- >van Geel, B. and Mook, W.G., 1989. High-resolution 14C dating of organic >deposits using natural atmospheric 14C variations. Radiocarbon 31: 151-156. > >Kilian, M.R., van der Plicht, J. and van Geel, B., 1995. Dating raised >bogs: new aspects of AMS 14C wiggle matching, a reservoir effect and >climatic change. Quaternary Science Reviews 14: 959-966. > >van Geel, B., Buurman, J. and Waterbolk, H.T., 1996. Archeological and >paleoecological indications for an abrupt climate change in The Netherlands >and evidence for climatological teleconnections around 2650 BP. Journal of >Quaternary Science 11: 451-460. > >van Geel, B., van der Plicht, J., Kilian, M.R., Klaver, E.R., Kouwenberg, >J.H.M., Renssen, H., Reynaud-Farrera, I. and Waterbolk, H.T., 1998. The >sharp rise of 14C ca. 800 cal BC: possible causes, related climatic >teleconnections and the impact on human environments. Radiocarbon 40: >535-550. > >van Geel, B., Renssen, H. and van der Plicht, J., 1998. Paleo-evidence for >solar forcing of climate change. Terra Nostra 98/6: 40-45. > >van Geel, B. and Renssen, H., 1998. Abrupt climate change around 2,650 BP >in North-West Europe: evidence for climatic teleconnections and a tentative >explanation. In: Water, Environment and Society in Times of Climatic >Change, Eds. Issar, A.S. and Brown, N., Kluwer, Dordrecht, p. 21-41. > >van Geel, B., Raspopov, O.M., van der Plicht, J. and Renssen, H., 1998. >Solar forcing of abrupt climate change around 850 calendar years BC. In: >Natural catastrophes during Bronze Age civilisations. Eds: B.J. Peiser, T. >Palmer and M.E. Bailey. BAR International Series 728: 162-168. > >van Geel, B., van der Plicht, J. and Renssen, H., 1999. Comment on "A large >California flood and correlative global climatic events 400 years ago" >(Schimmelmann et al., 1998). Quaternary Research 51: 108-110. > >van Geel, B., Raspopov, O.M., Renssen, H., van der Plicht, J., Dergachev, >V.A. and Meijer, H.A.J., 1999. The role of solar forcing upon climate >change. Quaternary Science Reviews 18: 331-338. > > >+--------------------------+-------------------------------------+ >| Dr Bas van Geel | Internet E-mail :vanGeel@bio.uva.nl | >| University of Amsterdam | Phone secr. :+31-20 525 7844 | >| Faculty of Biology | Direct phone :+31-20 525 7664 | >| Kruislaan 318 | Fax :+31-20 525 7662 | >| NL - 1098 SM Amsterdam | | >| The Netherlands | | >| | >| The Netherlands Centre for Geo-ecological Research (ICG) | >+--------------------------+-------------------------------------+ > > >