Nature 376, 156 - 159 (13 July 2002); doi:10.1038/376156a0

Unusual twentieth-century summer warmth in a 1,000-year temperature record from Siberia

Keith R. Briffa^*, Philip D. Jones^*, Fritz H. Schweingruber^†, Stepan G. Shiyatov^‡ & Edward R. Cook^§

^*Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
^†Swiss Federal Institute of Forest, Snow and Landscape Research, Zurcherstrasse 111, CH-8903 Birmensdorf, Switzerland
^‡Institute of Plant and Animal Ecology, Ural Branch of the Russian Academy of Sciences, 8 Marta Street, Ekaterinburg 620219, Russia
^§Tree-Ring Laboratory, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA

IN the current debate on the magnitude of modern-day climate change, there is a growing appreciation of the importance of long, high-resolution proxies of past climate^1–3. Such records provide an indication of natural (pre-anthropogenic) climate variability, either singly at specific geographical locations or in combination on continental and perhaps even hemispheric scales⁴. There are, however, relatively few records that are well dated, of high resolution and of verifiable fidelity in terms of climate response, and conspicuously few that extend over a thousand years or more⁵. Here we report a tree-ring-based reconstruction of mean summer temperatures over the northern Urals since AD 914. This record shows that the mean temperature of the twentieth century (1901–90) is higher than during any similar period since AD 914.

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