Climate records from corals

In many regions instrumental climate records are too short to resolve the full range of decadal- to multidecadal-scale natural climate variability. Massive annually banded corals from the tropical and subtropical oceans provide a paleoclimatic archive with a seasonal resolution, documenting past variations in water temperature, hydrologic balance, and ocean circulation. Recent coral-based paleoclimatic research has focused mainly on the tropics, providing important implications on the past variability of the El Nino-Southern Oscillation (ENSO) phenomenon and decadal tropical climate variability. However, new records from some of the rare subtropical/mid-latitude locations of coral growth were shown to reflect aspects of dominant modes of Northern Hemisphere climate variability, e.g. the North Atlantic Oscillation (NAO). This natural mode has important socio-economic impacts owing to its large-scale modulation of droughts, floods, storms, snowfall, and fish stocks at timescales relevant to society. Coral records extending over several centuries from key locations (e.g. northern Red Sea, Bermuda) provide the opportunity to assess recent shifts in the NAO with respect to the natural variability of the pre-instrumental period. Providing a better understanding of NAO dynamics, such paleoclimatic records, together with those derived from other paleoclimatic archives, are essential for the predictability of future European climate.