Our new study focuses on the heart of this period (14,000 to 9,000 years before present) by uranium-thorium dating of numerous fossil corals from the Tahitian barrier reef. During these five millennia, sea level rose by more than 50 m, the equivalent of all the Antarctic ice currently feeding the ocean. The average rate of sea-level rise is around one centimetre per year, three times that currently observed by satellite.
3With an unprecedented number of analyses, we have also been able to show that the rate of rise is correlated with global climatic events, notably the succession of warm and cold phases. In particular, we observed a slowdown in sea-level rise during the cold period of the Recent Dryas, and a synchronous acceleration during the Holocene Warm Period.
4This work has many implications for climatology, geophysics and other disciplines. The precise chronology of the deglaciation core is fundamental for estimating phase shifts between climatic forcings (insolation, atmospheric pCO2 ) and variations in mean temperature and sea level. This chronology is also crucial for estimating the dates of submergence of coastal areas and certain important basins: the opening of the Bering Strait and the straits of the Sea of Japan, the submergence of the Black Sea and the Persian Gulf (and the legends associated with the Flood), the closing of the Cosquer cave, etc...
5Several authors have established semi-empirical relationships between sea level and global temperature on time scales ranging from the last century to several millennia. This type of statistical relationship has even been used to revise upwards the IPCC's projections for the coming centuries. There is, however, a scientific debate on the uncertainties of this type of approach. Our observation of a correlation between sea level and temperature over the long term will be used in this context, as well as through real modelling of the ice caps of the time.
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Article published in La Lettre du Collège de France n° 28, April 2010
