Palcoclimatic records of northwest Pacific variations are scarce but can be extended by proxy records from old-aged trees around the North Pacific Rim. In July of 2001 on Kunashir Island at the southern extent of the Kuriles, tree cores were extracted from century-old oaks (Quercus crispula) and developed into a 400-year tree-ring width index series. Analyses showed the ring-width indices to correlate strongly with summer (June-September) temperatures as recorded at Ugno-Kurilsky on the Island. The summer temperatures were reconstructed using the tree-ring data and 52% of the variance was explained by the tree-ring indices. The recorded temperature data and the tree-ring data show similar correlation patterns with sea-surface temperatures (SSTs) of the North Pacific. Studies of North Pacific variations, as quantified by the Pacific Decadal Oscillation (PDO), show the PDO to be an important index of large-scale climate variation. The tree-ring series explains more than 33% of the variance of the July-September Pacific Decadal Oscillation and has similar spectral properties, further supporting the concept of multidecadal variation or shifts in North Pacific climate, for four centuries. (C) 2004 Elsevier B.V. All rights reserved.
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