Abstract

Sea-level fluctuations are the most direct and immediate consequence of climate change and will have severe impacts on coastal ecosystems, fresh water supplies as well as to densely populated coastal areas, including low-lying islands. Global mean sea level is projected to rise a few decimetres to over a metre by the year 2100. Higher rates of sea-level rise may be reached when modern ice sheets will rapidly deteriorate or collapse due to climate warming initiating a rise in the centimetre per year range by AD 2100. However, still predictions for centennial to millennial sea-level rise remain highly uncertain, primarily due to our relatively poor understanding of the sensitivity of the ice sheets to sustained warming and of the spatial and temporal sea-level variability on these time scales.

In low-latitude regions, away from former and present ice sheets (so-called “far-field” regions), reconstructed sea-level changes provide the most accurate and precise estimate of ice volume changes once they have been corrected for the influence of tectonic processes and glacial isostatic adjustment (GIA) - the deformational, gravitational and rotational response of the Earth to the ice-ocean mass exchanges associated with the glacial cycles. In contrast to typical mid-to-low latitude Atlantic sea-level curves that indicate continuously rising sea levels at a decelerating rate during the Holocene, far-field RSL records often display a highstand during the mid- to late-Holocene in the Pacific and in the eastern Indian Ocean. From this observation and based on high-precision GPS positioning as well as of U/Th dating accurate information regarding the melting history of ice sheets can be extracted from sea-level records of coral microatolls. Recent investigations showed that late Holocene Pacific sea-level highstand reached positions of around metre between 3.9 and 3.6 kyr BP, which corresponds to a glacio-eustatic contribution of meltwater of 1.5–2.5 m since 5.5 kyr BP, most likely sourced from the Antarctic ice sheet. All known aspects interfering with past glacial to interglacial sea-level rise including collapsing continental ice sheets for future prediction will be addressed during the lecture.

Biography

Anton Eisenhauer (AE) is a physicist and mathematician by training and professor for marine environmental geology and geochemistry at GEOMAR, Helmholtz Centre for Ocean Research, Kiel, Germany. AE applies radioactive (e.g. U/Th-Series), radiogenic (⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd etc.) as well as stable traditional (¹³C/¹²C, ¹⁸O/¹⁶O, etc.) and non-traditional isotopes (e.g. d^44/42Ca, d^88/86Sr, d¹¹B, etc.) to problems of marine geology, geochemistry and paleoclimatology. AE is interested in developing new so called non-traditional isotope systems like the d^44/42Ca and d^88/86Sr systems which can be applied to reconstruct and monitor bio-mineralisation processes in the marine realm. A research focus is directed to the application of U/Th disequilibrium dating to problems of glacial to interglacial sealevel change and their predictions to the Anthropocene. In recent years AE was involved in technology transfer processes to make marine analytical isotope techniques available for medical purposes.. AE is founder of the osteolabs (www.osteolabs.de) company focusing on determining natural d^44/42Ca isotope ratios in human blood and urine for the very early diagnosis of osteoporosis and prostate cancer. AE received varies awards and hold several patents in the field of medical applications of non-traditional isotope systems.