A magnetic signature of tree rings was tested as a potential paleo-climatic indicator. We examined wood from sequoia tree, located in Mountain Home State Forest, California, whose tree ring record spans over the period 600 - 1700 A.D. We measured low and high-field magnetic susceptibility, the natural remanent magnetization (NRM), saturation isothermal remanent magnetization (SIRM), and stability against thermal and alternating field (AF) demagnetization. Magnetic investigation of the 200 mm long sequoia material suggests that magnetic efficiency of natural remanence may be a sensitive paleoclimate indicator because it is substantially higher (in average >1%) during the Medieval Warm Epoch (700-1300 A.D.) than during the Little Ice Age (1300-1850 A.D.) where it is <1%. Diamagnetic behavior has been noted to be prevalent in regions with higher tree ring density. The mineralogical nature of the remanence carrier was not directly detected but maghemite is suggested due to low coercivity and absence of Verwey transition. Tree ring density, along with the wood's magnetic remanence efficiency, records the Little Ice Age (LIA) well documented in Europe. Such a record suggests that the European LIA was a global phenomenon. Magnetic analysis of the thermal stability reveals the blocking temperatures near 200 degree C. This phenomenon suggests that the remanent component in this tree may be thermal in origin and was controlled by local thermal condition.

Institute of Geology AS CR Prague 16502 Czech Republic

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Adams RK. Laboratory of Tree-Ring Research. Personal Communication. Tuscon, AZ ; 1999.

Stephens SL, Libby WJ. Anthropogenic fire and bark thickness in coastal and island pine populations from Alta and Baja California. Journal Of Biogeography. 2006;33:648–652. doi: 10.1111/j.1365-2699.2005.01387.x. DOI

Kletetschka G, Banerjee SK. Magnetic Stratigraphy Of Chinese Loess As A Record Of Natural Fires. Geophysical Research Letters. 1995;22:1341–1343. doi: 10.1029/95GL01324. DOI

Clark JS. Effect Of Climate Change On Fire Regimes In Northwestern Minnesota. Nature. 1988;334:233–235. doi: 10.1038/334233a0. DOI

Flanary BE, Kletetschka G. Analysis of telomere length and telomerase activity in tree species of various life-spans, and with age in the bristlecone pine Pinus longaeva. Biogerontology. 2005;6(2):101–111. doi: 10.1007/s10522-005-3484-4. PubMed DOI

Flanary BE, Kletetschka G. Analysis of telomere length and telomerase activity in tree species of various lifespans, and with age in the bristlecone pine Pinus longaeva. Rejuvenation Research. 2006;9:61–63. doi: 10.1089/rej.2006.9.61. PubMed DOI

Brem F, Tiefenauer L, Fink A, Dobson J, Hirt AM. A mixture of ferritin and magnetite nanoparticles mimics the magnetic properties of human brain tissue. Physical Review B. 2006;73

Kletetschka G, Zila V, Wasilewski PJ. Magnetic anomalies on the tree trunks. Studia Geophysica Et Geodaetica. 2003;47:371–379. doi: 10.1023/A:1023779826177. DOI

Jelinek V. Precision Ac Bridge Set For Measuring Magnetic Susceptibility Of Rocks And Its Anisotropy. Studia Geophysica Et Geodaetica. 1973;17:36–48. doi: 10.1007/BF01614027. DOI

Prihoda K, Krs M, Pesina B, Blaha J. MAVACS - a new system of creating a non-magnetic environment for paleomagnetic studies. Cuad Geol Iberica. 1989;12:223–250.

Bell M, Walker MJ. Late Quaternary environmental change. Physical and human perspectives. Longman Scientific and Technical; 1992. p. 273. PubMed

Grove JM. The onset of the Little Ice Age. In: Jones PD, Ogilvie AEJ, Davies TD, Briffa KR, editor. History and climate Memories of the future? Kluver Academic/Plenum Publishers; 2001. pp. 153–185.

Kletetschka G, Acuna MH, Kohout T, Wasilewski PJ, Connerney JEP. An empirical scaling law for acquisition of thermoremanent magnetization. Earth And Planetary Science Letters. 2004;226:521–528. doi: 10.1016/j.epsl.2004.08.001. DOI

Kletetschka G, Fuller MD, Kohout T, Wasilewski PJ, Herrero-Bervera E, Ness NF, Acuna MH. TRM in low magnetic fields: a minimum field that can be recorded by large multidomain grains. Physics Of The Earth And Planetary Interiors. 2006;154:290–298. doi: 10.1016/j.pepi.2005.07.005. DOI

Kletetschka G, Kohout T, Wasilewski PJ. Magnetic remanence in the Murchison meteorite. Meteoritics & Planetary Science. 2003;38:399–405.

Moberg A, Sonechkin DM, Holmgren K, Datsenko NM, Karlen W. Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data. Nature. 2005;433:613–617. doi: 10.1038/nature03265. PubMed DOI

Brazdil R. Reconstruction of past climate from historical sources in the Czech Lands. In: Jones PD, Bradley RS, Jouzel J, editor. Climatic variation and forcing mechanism of the last years. Berlin, Heidelberg , Springer; 1996. pp. 409–431.