Coral-reef records of Quaternary changes in climate and sea-level

Although coral reefs have long been regarded as documenting climate change, largely through its effects on sea-level, the temporal continuity and sensitivity to disturbance of their records appears to fall short of those provided by ice cores, deep-sea sediments and similar proxies. The reasons for this anomaly relate principally to shifts in the loci of deposition. The temporal windows in which accretion has been able to occur in a given place, reflecting sea level at a particular height relative to the present datum, are severely constrained. Where it has been possible, coral growth and reef accretion have been and are sensitive to the signals provided by the environment in the form of changes in water depth, temperature, salinity, nutrient supply, turbidity, and pH (acidity) concomitant with changes in sea-level itself. Changes in these environmental parameters are, directly or indirectly, controlled by climate. However, because the responses of corals to stimuli are commonly site-specific, and the nature of the changes evoked so disparate, it is likely that only major sea-level cycles will provide evidence of a consistent global response in what has been a segmented record.