<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE article SYSTEM "http://www.clim-past.net/inc/cp/copernicus.dtd">
<article language="en">
	<journal>
		<journal_title>Climate of the Past</journal_title>
		<journal_url>www.clim-past.net</journal_url>
		<issn>1814-9324</issn>
		<eissn>1814-9332</eissn>
		<volume_number>6</volume_number>
		<issue_number>3</issue_number>
		<publication_year>2010</publication_year>
	</journal>
	<doi>10.5194/cp-6-379-2010</doi>
	<article_url>http://www.clim-past.net/6/379/2010/</article_url>
	<abstract_html>http://www.clim-past.net/6/379/2010/cp-6-379-2010.html</abstract_html>
	<fulltext_pdf>http://www.clim-past.net/6/379/2010/cp-6-379-2010.pdf</fulltext_pdf>
	<start_page>379</start_page>
	<end_page>400</end_page>
	<publication_date>2010-06-25</publication_date>
	<article_title content_type="html">Millennium-long summer temperature variations in the European Alps as reconstructed from tree rings</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>C. Corona</name>
			<email>christophe.corona@gmail.com</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>J. Guiot</name>
		</author>
		<author numeration="3" affiliations="2">
			<name>J. L. Edouard</name>
		</author>
		<author numeration="4" affiliations="1">
			<name>F. ChaliÃ©</name>
		</author>
		<author numeration="5" affiliations="3">
			<name>U. BÃ¼ntgen</name>
		</author>
		<author numeration="6" affiliations="4">
			<name>P. Nola</name>
		</author>
		<author numeration="7" affiliations="5">
			<name>C. Urbinati</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">CEREGE, UMR 6635 CNRS/Aix-Marseille UniversitÃ©, BP 80, 13545 Aix-en-provence cedex 4, France</affiliation>
		<affiliation numeration="2" content_type="html">IMEP, UMR 6116 CNRS/Aix-Marseille UniversitÃ©, BP 80, 13545 Aix-en-provence cedex 4, France</affiliation>
		<affiliation numeration="3" content_type="html">Swiss Federal Research Institute WSL Zuercherstrasse 111 8903 Birmensdorf, Switzerland</affiliation>
		<affiliation numeration="4" content_type="html">Univ. degli Studi di Pavia, Dip. Ecologia del Territorio a degli Ambienti Terrestri, Via S. Epifanio, 14, 27100 Pavia, Italy</affiliation>
		<affiliation numeration="5" content_type="html">Univ. Politecnica delle Marche, Dip. SAPROV, Forest Ecology and Management, Via Brecce Bianche, 60131 Ancona, Italy</affiliation>
	</affiliations>
	<abstract content_type="html">This paper presents a reconstruction of the summer temperatures over the
Greater Alpine Region (44.05Â°â€“47.41Â° N, 6.43Â°â€“13Â° E) during
the last millennium based on a network of 38 multi-centennial larch and
stone pine chronologies. Tree ring series are standardized using an
Adaptative Regional Growth Curve, which attempts to remove the age effect
from the low frequency variations in the series. The proxies are calibrated
using the June to August mean temperatures from the HISTALP high-elevation
temperature time series spanning the 1818â€“2003. The method combines an
analogue technique, which is able to extend the too short tree-ring series,
an artificial neural network technique for an optimal non-linear calibration
including a bootstrap technique for calculating error assessment on the
reconstruction. About 50% of the temperature variance is reconstructed.
Low-elevation instrumental data back to 1760 compared to their instrumental
target data reveal divergence between (warmer) early instrumental
measurements and (colder) proxy estimates. The proxy record indicates cool
conditions, from the mid-11th century to the mid-12th century, related to
the Oort solar minimum followed by a short Medieval Warm Period (1200â€“1420).
The Little Ice Age (1420â€“1830) appears particularly cold between 1420 and
1820 with summers that are 0.8 Â°C cooler than the 1901â€“2000 period. The
new record suggests that the persistency of the late 20th century warming
trend is unprecedented. It also reveals significant similarities with other
alpine reconstructions.</abstract>
	<references>
		<reference numeration="1" content_type="text"> Anderson, T. L., Charlson, R. J., Schwartz, S. E., Knutti, R., Boucher, O., Rodhe, H., and Heintzenberg, J.: Climate forcing by aerosols â€“ A hazy picture, Science, 302, 1679â€“1681, 2003. </reference>
		<reference numeration="2" content_type="text"> Auer, I., BÃ¶hm, R., Jurkoviæ, A., Lipa, W., Orlik, A., Potzmann, R., SchÃ¶ner, W., UngersbÃ¶ck, M., Matulla, C., Briffa, K., Jones, P., Efthymiadis, D., Brunetti, M., Nanni, T., Maugeri, M., Mercalli, L., Mestre, O., Moisselin, J.-M., Begert, M., MÃ¼ller-Westermeier, G., Kveton, V., Bochnicek, O., Stastny, P., Lapin, M., Szalai, S., Szentimrey, T., Cegnar, T., Dolinar, M., Gajic-Capka, M., Zaninovic, K., Majstorovic, Z., and Nieplova, E.: HISTALP - historical instrumental climatological surface time series of the Greater Alpine Region, Int. J. Climatol., 27, 17â€“46, 2007. </reference>
		<reference numeration="3" content_type="text"> Bard, E., Raisbeck, G., Yiou, F., and Jouzel, J.: Comment on &quot;Solar activity during the last 1000 yr inferred from radionuclide records&quot; by Muscheler et al (2007), Quaternary Sci. Rev., 26, 2301â€“2308, 2007. </reference>
		<reference numeration="4" content_type="text"> Becker, M.: The role of climate on present and past vitality of silver fir in the Vosges mountains of northern France, Can. J. Forest Res., 19, 1110â€“1117, 1989. </reference>
		<reference numeration="5" content_type="text"> Begert, M., Schlegel T., and Kirchhofer W.: Homogeneous temperature and precipitation series of Switzerland for 1864 to 2000, Int. J. Climatol., 25, 65â€“80, 2005. </reference>
		<reference numeration="6" content_type="text"> BÃ¶hm, R., Auer, L., Brunetti, M., Maugeri, M., Nanni, D., and SchÃ¶ner, W.: Regional temperature variability in the European Alps: 1760â€“1998 from homogenized instrumental time series, Int. J. Climatol., 21, 1779â€“1801, 2001. </reference>
		<reference numeration="7" content_type="text"> BrÃ¡zdil, R., Pfister, C., Wanner, H., Von Storch, H., and Luterbacher, J.: Historical climatology in Europeâ€“-State of the art, Climate Change, 70, 363â€“430, 2005. </reference>
		<reference numeration="8" content_type="text"> Briffa, K. R., Jones, P. D., Bartholin, T. S., Eckstein, D., Schweingruber, F. H., KarlÃ©n, W., Zetterberg, P., and Eronen, M.: Fennoscandian summers from AD 500 â€“ temperature-changes on short and long timescales, Clim. Dynam., 7, 111â€“119, 1992. </reference>
		<reference numeration="9" content_type="text"> Briffa, K. R., Schweingruber, F. H., Jones, P. D., Osborn, T. J., Harris, I. C., Shiyatov, S. G., Vaganov, E. A., and Grudd, H.: &quot;Trees tell of past climates: but are they speaking less clearly today?&quot;, Philos. T. Roy. Soc. B., 353, 65â€“73, 1998. </reference>
		<reference numeration="10" content_type="text"> Briffa, K. R., Osborn, T. J., Schweingruber, F. H., Harris, I. C., Jones, P. D., Shiyatov, S. G., and Vaganov, E. A.: Low-frequency temperature variations from a northern tree-ring density network, J. Geophys. Res., 106, 2929â€“2941, 2001. </reference>
		<reference numeration="11" content_type="text"> Brunetti, M., Maugeri, M., Monti, F., and Nanni, T.: Temperature and precipitation variability in Italy in the last two centuries from homogenised instrumental time series, Int. J. Climatol., 26, 345â€“381, 2006. </reference>
		<reference numeration="12" content_type="text"> BÃ¼ntgen, U., Esper, J., Frank, D. C., Nicolussi, K., and Schmidhalter, M.: A 1052-year tree-ring proxy of Alpine summer temperatures, Clim. Dynam., 25, 141â€“153, 2005. </reference>
		<reference numeration="13" content_type="text"> BÃ¼ntgen, U., Frank, D. C., Nievergelt, D., and Esper, J.: Summer temperature variations in the European Alps, AD 755-2004, J. Climate, 19, 5606â€“5623, 2006a. </reference>
		<reference numeration="14" content_type="text"> BÃ¼ntgen, U., Bellwald, I., Kalbermatten, H., Schmidhalter, M., Freund, H., Frank, D.C., Bellwald, W., Neuwirth, B., NÃ¼sser, M., and Esper, J.: 700 years of settlement and building history in the LÃ¶tschental/Switzerland, Erdkunde, 60/2, 96â€“112, 2006b. </reference>
		<reference numeration="15" content_type="text"> BÃ¼ntgen, U., Frank, D., Wilson, R., and Esper, J.: A test for tree-ring divergence in the European Alps, Glob. Change Biol., 14, 2443â€“2453, 2008. </reference>
		<reference numeration="16" content_type="text"> Carrer, M. and Urbinati, C.: Age-dependent tree-ring growth responses to climate in Larix decidua and Pinus cembra., Ecology, 85, 730â€“740, 2004. </reference>
		<reference numeration="17" content_type="text"> Carrer, M. and Urbinati, C.: Long-term change in the sensitivity of treering growth to climate forcing in Larix decidua, New Phytol., 170, 861â€“872, 2006. </reference>
		<reference numeration="18" content_type="text"> Casty, C., Wanner, H., Luterbacher, J., Esper, J., and BÃ¶hm, R.: Temperature and precipitation variability in the European Alps since 1500, Int. J. Climatol., 25, 1855â€“1880, 2005. </reference>
		<reference numeration="19" content_type="text"> Chuine, I., Yiou, P., Viovy, N., Seguin, B., Daux, V., and LeRoy Ladurie, E.: Grape ripening as an indicator of past climate, Nature, 432, 289â€“290, 2004. </reference>
		<reference numeration="20" content_type="text"> Cook, E. and Kairiukstis, L.: Methods of dendrochronology, Kluwer, Dordrecht, 1990. </reference>
		<reference numeration="21" content_type="text"> Cook, E. R., Briffa, K. R., and Jones, P. D.: Spatial regression methods in dendroclimatology: A review and comparison of two techniques, Int. J. Climatol., 14, 379â€“402, 1994. </reference>
		<reference numeration="22" content_type="text"> Cook, E. R., D&apos;Arrigo, R. D., and Mann, M. E.: A well-verified, multiproxy reconstruction of the Winter North Atlantic Oscillation Index since AD 1400, J. Climate, 15, 1754â€“1764, 2002. </reference>
		<reference numeration="23" content_type="text"> Crowley, T. J.: Causes of climate change over the past 1000 years, Science, 295, 270â€“277, 2000. </reference>
		<reference numeration="24" content_type="text"> D&apos;Arrigo, R., Wilson, R., and Jacoby, G.: On the long-term context for late twentieth century warming, J. Geophys. Res., 111, D03103, doi:10.1029/2005JD006352, 2006. </reference>
		<reference numeration="25" content_type="text"> Dai, J., Mosley-Thompson, E., and Thompson, L. G.: Ice core evidence for an explosive tropical volcanic eruption 6 years preceding Tambora, J. Geophys. Res., 96, 17361â€“17366, 1991. </reference>
		<reference numeration="26" content_type="text"> Eddy, J. A.: The maunder minimum, Science, 192, 1189â€“1202, 1976. </reference>
		<reference numeration="27" content_type="text"> Efron, B.: Bootstrap methods: another look at the jackknife, The Annals of Statistics, 7, 1â€“26, 1979. </reference>
		<reference numeration="28" content_type="text"> Esper, J., Cook, E. R., and Schweingruber, F. H.: Low-frequency signals in long tree-ring chronologies for reconstructing past temperature variability, Science, 295, 2250â€“2253, 2002. </reference>
		<reference numeration="29" content_type="text"> Esper, J., Niederer, R., Bebi, P., and Frank, D: Climate signal age effects â€“ Evidence from young and old trees in the Swiss Engadin, Forest Ecol. Manag., 255, 3783â€“3789, 2008. </reference>
		<reference numeration="30" content_type="text"> Etien, N., Daux, V., Masson-Delmotte, V., Stievenard, M., Bernard, V., Durost, S., Guillemin, M. T., Mestre, O., and Pierre, M.: A bi-proxy reconstruction of Fontainebleau (France) growing season temperature from AD 1596 to 2000, Clim. Past, 4, 91â€“106, doi:10.5194/cp-4-91-2008, 2008. </reference>
		<reference numeration="31" content_type="text"> Folland, C. K., Rayner, N. A., Brown, S. J., Smith, T. M., Shen, S. S. P., Parker, D. E., Macadam, I., Jones, P. D., Jones, R. N., Nicholls, N., and Sexton, D. M. H.: Global temperature change and its uncertainties since 1861, J. Geophys. Res., 28, 2621â€“2624, 2001. </reference>
		<reference numeration="32" content_type="text"> Frank, D. and Esper, J.: Temperature reconstructions and comparisons with instrumental data from a tree-ring network for the European Alps, Int. J. Climatol., 25, 1437â€“1454, 2005. </reference>
		<reference numeration="33" content_type="text"> Frank, D., BÃ¼ntgen, U., BÃ¶hm, R., Maugeri, M., and Esper, J.: Warmer early instrumental measurements versus colder reconstructed temperatures: shooting at a moving target, Quaternary Sci. Rev., 28, 3298â€“3310, 2007a. </reference>
		<reference numeration="34" content_type="text"> Frank, D., Esper, J., and Cook, E. R.: Adjustment for proxy number and coherence in a large-scale temperature reconstruction, Geophys. Res., 34, doi:10.1029/2007GL030571, 2007b. </reference>
		<reference numeration="35" content_type="text"> Fritts, H. C.: Tree Rings and Climate, Academic Press, 1976. </reference>
		<reference numeration="36" content_type="text"> GarcÃ­a de CortÃ¡zar-Atauri, I., Daux, V., Garnier, E., Yiou, P., Viovy, N., Seguin, B., Boursiquot, J.M., Parker, A.K., van Leeuwen, C., and Chuine I.: Climate reconstructions from grape harvest dates: Methodology and uncertainties, The Holocene, doi:10.1177/0959683609356585, 2010. </reference>
		<reference numeration="37" content_type="text"> Grove, J. M.: The Little Ice Age, Methuen and Co., London, New York, 1988. </reference>
		<reference numeration="38" content_type="text"> Guiot, J.: Methods of calibration, verification and reconstruction, in: Methods of denrochronology, application in the environmental sciences, edited by: Cook, E. and Kairiukstis, L., Dordrecht, International Institute for Applied Systems Analysis, Kluwer Academy Publications, 163â€“217, 1990. </reference>
		<reference numeration="39" content_type="text"> Guiot, J., Nicault, A., Rathgeber, C., Edouard, J.-L., Guibal, F., Pichard, G., and Till, C.: Last-millennium summer-temperature variations in western Europe based on proxy data, The Holocene, 15, 489â€“500, 2005. </reference>
		<reference numeration="40" content_type="text"> Harrington, C. D.: The Year without a Summer? World Climate in 1816, Canadian Museum of Nature, Ottawa, 1992. </reference>
		<reference numeration="41" content_type="text"> Holzhauser, H., Magny, M., and ZumbÃ¼hl, H. J.: Glacier and lake-level variations in west-central Europe over the last 3500 years, The Holocene, 15, 789â€“801, 2005. </reference>
		<reference numeration="42" content_type="text"> Hughes, M. K. and Diaz, H. F.: Was there a &quot;Medieval Warm Period&quot; and if so, where and when?, Climatic Change, 26, 109â€“142, 1994. </reference>
		<reference numeration="43" content_type="text"> Jones, P. D., Osborn, T. J., and Briffa, K. R.: The evolution of climate over the last millennium, Science, 292, 662â€“666, 2001. </reference>
		<reference numeration="44" content_type="text"> Jones, P. D. and Mann, M. E.: Climate over past millennia, Rev. Geophys., 42, RG2002, doi:10.1029/2003RG000143, 2004. </reference>
		<reference numeration="45" content_type="text"> Lamb, H. H.: Climate: present, past and future, London: Methuen, 1976. </reference>
		<reference numeration="46" content_type="text"> Lachiver, M.: Vins, Vignes et Vignerons: Histoire du Vignoble FranÃ§ais, Fayard, Paris, 1988. </reference>
		<reference numeration="47" content_type="text"> LeRoy Ladurie, E.: Histoire humaine et comparÃ©e du climat, Vol 1: Canicules et glaciers XIII-XVIII siÃ¨cles, Fayard, 740pp., Paris, 2004. </reference>
		<reference numeration="48" content_type="text"> Luterbacher, J., Rickli, R., Xoplaki, E., Tinguely, C., Beck, C., Pfister, C., and Wanner, H.: The Late Maunder Minimum (1675â€“1715) â€“ A key period for studying decadal scale climate change in Europe, Climate Change, 49, 441â€“462, 2001. </reference>
		<reference numeration="49" content_type="text"> Luterbacher, J., Xoplaki, E., Dietrich, D., Jones, P. D., Davies, T. D., Portis, D., Gonzalez- Rouco, J. F., von Storch, H., Gyalistras, D., Casty, C., and Wanner, H.: Extending North Atlantic Oscillation reconstructions back to 1500, Atmos. Sci. Lett., 2, 114â€“124, 2002. </reference>
		<reference numeration="50" content_type="text"> Luterbacher, J., Dietrich, D., Xoplaki, E., Grosjean, M., and Wanner, H.: European seasonal and annual temperature variability, trends, and extremes since 1500, Science, 303, 1499â€“1504, 2004. </reference>
		<reference numeration="51" content_type="text"> Luterbacher, J., Dietrich, D., Xoplaki, E., Grosjean, M., and Wanner, H.: European Seasonal Temperature Reconstructions. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2006-060. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA, 2006. </reference>
		<reference numeration="52" content_type="text"> Mangini, A., Spoetl, C., and Verdes, P.: Reconstruction of temperature in the Central Alps during the past 2000 year from a d18O stalagmite record, Earth Planet. Sc. Lett., 235, 741â€“751, 2005. </reference>
		<reference numeration="53" content_type="text"> Mann, M. E., Bradley, R. S., and Hughes, M. K.: Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations, Geophys. Res. Lett., 26, 759â€“762, 1999. </reference>
		<reference numeration="54" content_type="text"> Mann, M. E., Gille, E., Bradley, R. S., Hughes, M. K., Overpeck, J. T., Keimig, F. T., and Gross, W.: Global temperature patterns in past centuries: an interactive presentation, Earth Interactions, 4, 1â€“29, 2000. </reference>
		<reference numeration="55" content_type="text"> Mann, M. E. and Jones, P. D.: Global Surface Temperatures over the Past Two Millennia, Geophys. Res. Lett., 30, doi:10.1029/2003GL017814, 2003. </reference>
		<reference numeration="56" content_type="text"> Mann, M. E.: Clmate over the Past two millennia, Annu. Earth Planet. Sci., 35, 111â€“136, 2007. </reference>
		<reference numeration="57" content_type="text"> Matulla, C., Auer, I., BÃ¶hm, R., UngersbÃ¶ck, M., SchÃ¶ner, W., Wagner, S., and Zorita, E.: Outstanding past decadal-scale climate events in the Greater Alpine region analysed by 250 years data and model runs, GKSS-Report 2005/4, GKSS Forschungszentrum in der Helmholtz Gemeinschaft, Geesthacht, 2005. </reference>
		<reference numeration="58" content_type="text"> Meehl, G. A., Washington, W. M., Wigley, T. M. L., Arblaster, J. M., and Dai, A.: Solar and greenhouse gas forcing and climate response in the twentieth century, J. Climate, 16, 426â€“444, 2003. </reference>
		<reference numeration="59" content_type="text"> Meier, N., Rutishauser, T., Pfister, C., Wanner H., and Luterbacher, J.: Grape harvest dates as proxy for Swiss April to August temperature reconstructions back to AD 1480, Geophys. Res. Lett., 34, L20705, doi:10.1029/2007GL031381, 2007. </reference>
		<reference numeration="60" content_type="text"> Moberg, A., Alexandersson, H., BergstrÃ¶m, H., and Jones, P. D.: Were Southern Swedish summer temperatures before 1860 as warm as measured?, Int. J. Climatol., 23, 1495â€“1521, 2003. </reference>
		<reference numeration="61" content_type="text"> Moberg, A. D., Sonechkin, M., Holmgren, K., Datsenko, N. M., and Karlen, W.: Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data, Nature, 433, 613â€“617, 2005. </reference>
		<reference numeration="62" content_type="text"> Mitchell, T. D., Hulme, M., and New, M.: Climate data for political areas, Area, 34, 109â€“112, 2002. </reference>
		<reference numeration="63" content_type="text"> Mitchell, T. D. and Jones, P.: An improved method of constructing a database of monthly climate observations and associated high-resolution grids, Int. J. Climatol., 25, 693â€“712, 2005. </reference>
		<reference numeration="64" content_type="text"> New, M., Hulme, M., and Jones, P. D.: Representing twentieth-century space â€“ time climate variability. Part II: development of 1901â€“96 monthly grids of terrestrial surface climate, J. Climate, 13, 2217â€“2238, 2000. </reference>
		<reference numeration="65" content_type="text"> Ni, F., Cavazos, T., Hughes, M. K., Combrie, A., and Funkhouser, G.: Cool-season precipitation in the Southwestern USA since AD 1000: comparison of linear and non linear techniques for reconstruction, Int. J. Climatol., 22, 1645â€“1662, 2002. </reference>
		<reference numeration="66" content_type="text"> Nicault, A., Alleaume, S., Brewer, S., Carrer, M., Nola, P., and Guiot, J.: Mediterranean drought fluctuation during the last 500 years based on tree-ring data, Clim. Dynam., 31, 227â€“245, 2008. </reference>
		<reference numeration="67" content_type="text"> Nicault, A., Guiot, J., Edouard, J.-L., and Brewer, S.: Preserving long-term fluctuations in standardization of tree-ring series by the Adaptative Regional Growth Curve (ARGC), Dendrochronologia, 28, 1â€“12, 2010. </reference>
		<reference numeration="68" content_type="text"> Oerlemans, J.: Extracting a climate signal from 169 glacier records, Science, 308, 675â€“677, 2005. </reference>
		<reference numeration="69" content_type="text"> Oppenheimer, C.: Climatic, environmental and human consequences of the largest known historic eruption: Tambora volcano (Indonesia) 1815, Prog. Phys. Geog., 27, 230â€“259, 2003. </reference>
		<reference numeration="70" content_type="text"> Pauling, A., Luterbacher, J., Casty C., and Wanner, H.: Five hundred years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation, Clim. Dynam., 26, 387â€“405, 2006. </reference>
		<reference numeration="71" content_type="text"> Pfister, C.: Monthly temperature and precipitation patterns in Central Europe from 1525 to the present. A methodology for quantifying man made evidence on weather and climate, in: Climate since 1500 AD, edited by: Bradley, R. S. and Jones, P. D., London, 118â€“143, 1992. </reference>
		<reference numeration="72" content_type="text"> Pfister, C., Kington, J., Kleinlogel, G., Schuele, H., and Siffert, E.: The creation of highresolution spatio-temporal reconstructions of past climate from direct meteorological observations and proxy data, Methodological considerations and results, in: Climate in Europe 1675â€“1715, edited by: Frenzel, B., Pfister, C., and Glaeser, B., 1994. </reference>
		<reference numeration="73" content_type="text"> Pfister, C.: Wetternachhersage, 500 Jahre Klimavariationen und Naturkatastrophen 1496â€“1995, Haupt Verlag, 1999. </reference>
		<reference numeration="74" content_type="text"> Rathgeber, C., Guiot, J., Roche, P., and Tessier, L.: Augmentation de productivitÃ© du chÃªne pubescent en rÃ©gion mÃ©diterranÃ©enne franÃ§aise, Ann. Sci. Forest., 56, 201â€“209, 1999. </reference>
		<reference numeration="75" content_type="text"> Richman, M. B.: Rotation of principal components, J. Climatol., 6, 293â€“335, 1986. </reference>
		<reference numeration="76" content_type="text"> Robock, A.: Review of year without a summer? World climate in 1816, Climate Change, 26, 105â€“108, 1994. </reference>
		<reference numeration="77" content_type="text"> Schneider, T.: Analysis of incomplete climate data: estimation of mean values and covariance matrices and imputation of missing values, J. Climate, 14, 853â€“871, 2001. </reference>
		<reference numeration="78" content_type="text"> Shindell, D. T., Schmidt, G. A., Mann, M. E., Rind, D., and Waple, A.: Solar forcing of regional climate change during the Maunder Minimum, Science, 294, 2149â€“2152, 2001. </reference>
		<reference numeration="79" content_type="text"> Sigurdsson, H. and Carey, S.: Plinian and co-ignimbrite tephra fall from the 1815 eruption of Tambora volcano, B. Volcanol., 51, 243â€“270, 1989. </reference>
		<reference numeration="80" content_type="text"> Wanner, H., Pfister, C., Brazdil, R., Frich, P., and Frydendah, K.: Wintertime European circulation patterns during the late Maunder minimum cooling period [1675-1704], Theor. Appl. Climatol., 51, 167â€“175, 1995. </reference>
		<reference numeration="81" content_type="text"> Wigley, T. M. L., Briffa, K. R., and Jones, P. D.: On the average of value of correlated time series, with applications in dendroclimatology and hydrometeorology, J. Clim. Appl. Meteorol., 23, 201â€“213, 1984. </reference>
		<reference numeration="82" content_type="text"> Woodhouse, C. A.: Artificial neural networks and dendroclimatic reconstructions: an example from the Front Range, Colorado, USA, The Holocene, 9, 521â€“529, 1999. </reference>
		<reference numeration="83" content_type="text"> Xoplaki, E., Luterbacher, J., Paeth, H., Dietrich, D., Steiner, N., Grosjean, M., and Wanner, H.: European spring and autumn temperature variability and change of extremes over the last half millennium, Geophys. Res. Lett., 32, L15713, doi:10.1029/2005GL023424, 2005. </reference>
		<reference numeration="84" content_type="text"> ZumbÃ¼hl, H. J., Steiner, D., and Nussbaumer, S. U.: 19th century glacier representations and fluctuations in the central and western European Alps: an interdisciplinary approach, Global Planet. Change, 60, 42â€“57, 2008. </reference>
	</references>
</article>

