A reconstruction of the North Atlantic Oscillation using tree-ring chronologies from North America and Europe

Tree-ring records, six from eastern North America and four from northwestern Europe, are used to develop the first reconstruction of the winter North Atlantic Oscillation (NAG). The reconstructed series spans the interval AD 1701-1980 and explains 41% of the variance in the NAO over the AD 1874-1980 calibration period. The reconstruction also captures the spectral properties of this index, suggesting that the oscillatory character of the NAO is a long-term feature of the North Atlantic climate system.