HR: 10:35h
AN: GC11A-02 INVITED     [PDF]
TI: Rates and magnitudes of sea-level change: lessons from the past for the future
AU: * Rohling, E J
EM: E.Rohling@soc.soton.ac.uk
AF: School of Ocean and Earth Science, Southampton Oceanography Centre, Southampton, SO14 3ZH United Kingdom
AU: Siddall, M
EM: ms14@soc.soton.ac.uk
AF: School of Ocean and Earth Science, Southampton Oceanography Centre, Southampton, SO14 3ZH United Kingdom
AU: Smeed, D A
EM: D.A.Smeed@soc.soton.ac.uk
AF: School of Ocean and Earth Science, Southampton Oceanography Centre, Southampton, SO14 3ZH United Kingdom
AB: The Red Sea is highly evaporative, and has very limited communication with the open ocean. This makes it very sensitive to changes in sea level. Any reduction in sea level immediately affects the residence times of water within the basin, with strong implications for salinity and oxygen isotope ratios. We have explored the quantitative relationship between stable oxygen isotope changes in the Red Sea and sea level change, using a hydraulic control+basin model. Using oxygen isotope records from foraminifera in Red Sea sediment cores, we then reconstruct past sea level histories. We use generous allowances for uncertainties in Temperature, Humidity, and Evaporation Rate to determine confidence limits to these sea-level reconstructions. The method is validated by comparing results for the last deglaciation and for the last 470,000 years with fossil reef and deep-sea isotope data. Next, we apply the method to determine sea level variations associated with the millennial-scale climate variability of the last glacial cycle. We find that sea-level variations during that period were much larger than previously thought (up to 35-45 m), and that the timing of these sea-level changes coincided closely with temperature fluctuations at the high southern latitudes (as recorded in Antarctic ice cores). Rates of change were in the order of a staggering 2 m per century, similar to the mean rate of change observed over the last deglaciation (which peaked at ~4-5 m per century). New preliminary results suggest that more than half of the amplitude of these sea-level fluctuations originated from Antarctica. Given that the combined Antarctic ice cover today comprises the equivalent of 66 m global sea level rise, our finding that Antarctica contributed extensively to the sea-level variability associated with past abrupt climate changes calls for intensified research on its potential long-term responses to global greenhouse warming.
DE: 4267 Paleoceanography
DE: 4556 Sea level variations
DE: 4842 Modeling
DE: 4870 Stable isotopes
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting