Nature 346, 434 - 439 (02 August 1990); doi:10.1038/346434a0

A 1,400-year tree-ring record of summer temperatures in Fennoscandia

K. R. Briffa^*, T. S. Bartholin^†, D. Eckstein^‡, P. D. Jones^*, W. Karlén^§, F. H. Schweingruber & P. Zetterberg^¶

^* Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
^† Laboratory of Quaternary Biology, University of Lund, Tornavägen 13, S-22363 Lund, Sweden
^‡ Institute of Wood Biology, University of Hamburg, Leuschnerstrasse 91, D-2050 Hamburg 80, FRG
^§ Department of Physical Geography, University of Stockholm, S-106 91 Stockholm, Sweden
Swiss Federal Institute of Forest, Snow and Landscape Research, Zücherstrasse 11, CH-8903 Birmensdorf, Switzerland
^¶ Karelian Institute, Section of Ecology, University of Joensuu, PO Box 111, SF-80101 Joensuu, Finland

Tree-ring data have been used to reconstruct the mean summer (April-August) temperature of northern Fennoscandia for each year from AD 500 to the present. Summer temperatures have fluctuated markedly on annual, decadal and century timescales. There is little evidence for the existence of a Medieval Warm Epoch, and the Little Ice Age seems to be confined to the relatively short period between 1570 and 1650. This challenges the popular idea that these events were the major climate excursions of the first millennium, occurring synchronously throughout Europe in all seasons. An analysis of past warming trends suggests that any summer warming induced by greenhouse gases may not be detectable in this region until after 2030.

References

1.	Bartholin, T. S. & Karlén, W. Dendrokronologiska Sällskapets Meddelanden 5, 3−16 (1983).
2.	Bartholin, T. S. Ann. Acad. Sci. Fennicae Alll 145, 79−88 (1987).
3.	Schweingruber, F. H., Bartholin, T., Schär, E. & Briffa, K. R. Boreas 17, 559−566 (1988).
4.	Garfinkel, H. L. & Brubaker, L. B. Nature 286, 872−874 (1980). | Article | ISI |
5.	Jacoby, G. C. & Cook, E. H. Arct. Alp. Res. 13, 409−418 (1981).
6.	Aniol, R. W. & Eckstein, D. Climate Changes on a Yearly to Millennial Basis (eds Mörner, N-A. & Karlén, W.) 261−262 (Reidel, Dordrecht, 1984).
7.	Briffa, K. R., Jones, P. D., Pilcher, J. R. & Hughes, M. K. Arct. Alp. Res. 20, 385−242 (1988).
8.	Karlén, W. Climate Changes on a Yearly to Millennial Basis (eds Mörner, N. A. & Karlén, W.) 263−271 (Reidel, Dordrecht. 1984).
9.	Fritts, H. C. Tree Rings and Climate (Academic, London, 1976).
10.	Cook, E. R., Briffa, K. R., Shiyatov, S. G. & Mazepa, V. S. Methods of Dendrochronology (eds Cook, E. R. & Kairiukstis, L. A.) 104−123 (Kluwer, Dordrecht, 1989).
11.	Wigley, T. M. L., Briffa, K. R. & Jones, P. D. J. Clim. appl. Met. 23, 201−213 (1984).
12.	Jones, P. D. et al. A Grid Point Surface Air Temperature Data Set for the Northern Hemisphere, 1851−1984. DOE Tech. Rep. TR022 (US Department of Energy, Washington, DC, 1985).
13.	Hustich, I. Acta Bot. Fennica 42, 1−75 (1948).
14.	Sirén, G. Communicationes Instituti Forestalls Fenniae 54 (1961).
15.	Briffa, K. R. et al. J. Clim. 3, 233−242 (1983).
16.	Bradley, R. S., Kelly, P. M., Jones, P. D., Goodess, C. M. & Diaz, H. F. A Climatic Data Bank for Northern Hemisphere Land Areas. 1851−1980. DOE Tech. Rep. TR017 (US Department of Energy, Washington, DC, 1985).
17.	Lamb, H. H. Climate Vol. 2 (Methuen, London, 1977).
18.	Williams, L. D. & Wigley, T. M. L. Quat. Res. 20, 286−307 (1983). | Article |
19.	Grove, J. M. The Little Ice Age (Methuen, London, 1988).
20.	Wigley, T. M. L., Farmer, G. & Ogilvie, A. E. J. Current Issues in Climate Research (eds Ghazi, A. & Fantechi, R.) 97−99 (Reidel, Dordrecht, 1984).
21.	Wigley, T. M. L. The Greenhouse Effect Lecture presented at the prime minister's seminar on global climate change, UK Department of the Environment (1989).
22.	Santer, B. D., Wigley, T. M. L., Schlesinger, M. E. & Mitchell, J. F. B. Developing Climate Scenarios from Equilibrium G.C.M. Results, Rep. 47 (Max Planck institut für Meteorologie, Hamburg, 1990).
23.	Wigley, T. M. L. & Raper, S. C. B. Nature 344, 324−327 (1990). | Article | ISI |