GLOBAL INTERDECADAL AND CENTURY-SCALE CLIMATE OSCILLATIONS DURING THE PAST 5 CENTURIES

The recognition of natural modes of climate variability is essential for a better understanding of the factors that govern climate change. Recent models suggest that interdecadal (roughly 15-35-year period)(1-4) and century-scale (roughly 50-150-year period)(5-7) climate variability may be intrinsic to the natural climate system. While there is some evidence for the existence of interdecadal(8,9) and century-scale(9,10) oscillations in instrumental temperature records, confident detection from these short (100-400-year) records is difficult(11,12). Oscillations on the same timescales(5,13-17) have also been detected in isolated climate-proxy or historical records over longer durations, but the large-scale spatial structure of the variability has not been investigated systematically. Here we report the multivariate analysis of a globally distributed set of temperature proxy records of several centuries 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 histories of these signals.