From WEFER G, LAMY F, MANTOURA F (eds), 2003, Marine Science Frontiers for Europe. Springer-Verlag Berlin Heidelberg New York Tokyo, pp 11-27 Climate Records from Corals T. Felis * and J. Pätzold Universität Bremen, Fachbereich Geowissenschaften, Klagenfurter Straße, 28359 Bremen, Germany * corresponding author (e-mail): tfelis@uni-bremen.de Abstract: 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 Niño-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. Introduction Instrumental climate records are too short to re- solve the full range of decadal- to multidecadal- scale natural climate variability. Banded corals, tree rings, ice cores, and varved sediments provide paleoclimatic archives which can be used to recon- struct past climate variability in the pre-instrumen- tal period in annual resolution. These proxy climate indicators provide paleoclimatic records which are important for the assessment of perturbations to the natural climate variability by anthropogenic forc- ing, for climate predictability and for a better un- derstanding of the dominant modes of the global climate system, e.g. the El Niño-Southern Oscilla- tion (ENSO) phenomenon of tropical Pacific ori- gin, the Asian and African monsoon, the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO), and the mechanisms of decadal climate variability. These natural modes have im- portant socio-economic effects owing to their large-scale modulation of droughts, floods, storms, snowfall, or fish stocks at timescales relevant to society. Massive "stony" (scleractinian) corals from the modern and fossil reefs of the tropical and subtropi- cal oceans provide an important archive of past cli- mate and ocean variability. These corals build skel- etons of aragonite (CaCO 3 ) and grow at rates of millimeters to centimeters per year. During growth, annual density bands are produced in the skeleton that can be used for the development of chronolo- gies. As corals grow they incorporate isotopic and elemental tracers reflecting the environmental con- ditions in the ambient seawater during skeleton se- cretion, e.g. water temperature, hydrologic balance (evaporation, precipitation, runoff), and ocean cir- culation. Compared to other paleoclimatic archives corals provide a clear seasonal resolution. Modern corals from living reefs provide continuous climate