Although tropical oceans are a key component of the global climate system, their behavior in the past - even only a few decades ago - remains poorly characterized. Coral skeletons can provide several centuries of continuous paleoclimatic records with weekly to annual resolution. The skeletal oxygen isotope ratio (δ<sup>18</sup>O) is one of the most commonly used coral-based paleoclimatic proxies. The skeletal δ<sup>18</sup>O values reflect a combination of temperature and the δ<sup>18</sup>O of ambient surface seawater, and seawater δ<sup>18</sup>O and sea surface salinity are affected by similar factors. Many calibration studies have sought to validate skeletal δ<sup>18</sup>O as a paleoclimatic tracer and to define the relationship between skeletal δ<sup>18</sup>O, temperature, seawater δ<sup>18</sup>O and salinity. The time resolution of this calibration is increasing; it currently occurs biweekly in the Palau Islands in the tropical Western Pacific. Generally, changes in sea surface temperature and seawater δ<sup>18</sup>O have almost the same effect on changes in skeletal δ<sup>18</sup>O, both temporally and spatially. Local contribution rates of these two factors to skeletal δ<sup>18</sup>O differ owing to regional climatic conditions. Parallel studies of detailed calibrations and an expansion of coral skeletal δ<sup>18</sup>O datasets over the next decade are anticipated to lead to many developments in paleoclimatic understanding.
Stable isotopes in deep-sea corals and a new mechanism for "vital effects"
The southern oscillation recorded in the δ^8O of Corals from Tarawa Atoll.
Tropical temperature variations since 20,000 years age : Modulating interhemispheric climate change.
A multicentury stable isotope record from a New Caledonia coral : Interannual and decadal sea surface temperature variability in the southwest Pacific since 1657 A. D.
Surface ocean variability at Galapagos from 1936-1982 : calibration of geochemical tracers in corals.