GLOBAL INTERDECADAL AND CENTURY-SCALE CLIMATE OSCILLATIONS DURING THEPAST 5 CENTURIES

The recognition of natural modes of climate variability is essential f or a better understanding of the factors that govern climate change. R ecent models suggest that interdecadal (roughly 15-35-year period)(1-4 ) and century-scale (roughly 50-150-year period)(5-7) climate variabil ity may be intrinsic to the natural climate system. While there is som e evidence for the existence of interdecadal(8,9) and century-scale(9, 10) oscillations in instrumental temperature records, confident detect ion from these short (100-400-year) records is difficult(11,12). Oscil lations on the same timescales(5,13-17) have also been detected in iso lated climate-proxy or historical records over longer durations, but t he large-scale spatial structure of the variability has not been inves tigated systematically. Here we report the multivariate analysis of a globally distributed set of temperature proxy records of several centu ries duration. The results of our spatio-temporal analysis strengthen evidence for persistent natural interdecadal and century-scale climate oscillations, and reveal both the spatial patterns and temporal histo ries of these signals.