Through this research expedition, IODP scientists aim to learn more about the timing and course of past global sea level changes to better understand present and future sea level rise due to global greenhouse conditions. Since the climax of the last ice age, global sea level has risen by about 120 meters, primarily because of the melting of large inland ice sheets and thermal expansion of the global body of ocean water?attributable to rising temperatures.
According to IODP scientists, Tahiti is well situated for these investigations because the island is located in a tectonically stable region. Consequently, changes in sea level here can be related solely to global effects. Because the corals off Tahiti have strict ecological requirements and are extremely sensitive to environmental changes, both natural and human-induced, they are accurate, sensitive recorders of past sea level and climatic change.
The science party will analyze fossil, i.e. dead corals, because they form archives that help decipher the long-term behavior of the tropical ocean-atmosphere system and how it has responded to manmade and natural impacts. Live corals will not be cored, nor analyzed.
Because corals live in a sufficiently narrow depth range, they can be used as absolute sea level indicators. Corals can be considered chronometers as they can absolutely date by radiometric methods, methods so accurate that even in the oldest coral rocks to be studied, scientists will be able to accurately determine the age of corals to within 50 years.
Expedition co-chief scientist Yasufumi
Contact: Nancy Light
Integrated Ocean Drilling Program Management International