Climatic Change Over the Last Millennium in Tasmania Reconstructed from Ttee-Rings E
TheHolocene 2,3 (19921pp.205-277 Climatic change over the last millennium in Tasmania reconstructed from ttee-rings E. Cook*,T.Birdt, M. Petersono,M. Barbettif,B. Buckleyn, R. D'Arrigo*and R. Francey** (*Lamont-DohertyGeological Observatory, Palisades, New York 10964,USA; fTasmania Tradesand Labor Council, New Town, Tasmania7008, Australia; "TasmaniaForestry Commission,Hobart, Tasmania7001, Australia; iUniversity of Sydney,Sydney, New South Wales2006, Australia; x*CSlRO Division of AtmosphericResearch, Mordialloc, Victoria 3195,Australia) ReceivedL4 January1.992; revised manuscript accepted 26 May 1992 Abstract Tree-ring widths from millennium-old Huon pine (Lagarostrobosfranklinii) trees have been used to reconstructwann season(November-April) temperaturesback to AD 900 for Tasmania.The reconstructionindicates that the most recent 100 years of climate have been highly unusual,with the coldest and warmest 25-year periods occurring from 1890 to l9L4 and 1965 to 1989, respectively. Although the most recent 25-year period is warmer than any comparable period over the past 1090 years,it is not yet statisticallyunprecedented. Some evidencefor the Medieval Warm Period and the 'Little Ice Age' can be found in the reconstruction, especiallyduring the twelfth and seventeenth centuries respectively.However, the latter is weakly expressedcompared to many records from the northern hemisphere,suggesting that the southernoceans may havesignificantly moderated its effect on Tasmania.Regular oscillationson the order of 30, 56, 80 and 180years in length have been identified in A the reconstructionusing spectralanalysis. These oscillationscannot be easilylinked to climatic forcing HOLOCENE functions related to solar or volcanic activity. Thus, they are best regardedas arisingfrom the internal RESEARCH PAPER dynamicsof the ocean-atmosphere-cryospheresystem. Key words: climatic variations,tree-rings, Lagarostrobos franklinii,Tasmania, Medieval Warm Period, Little Ice Age, spectral analysis.
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