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Seminar Details

Paleoceanography of the Red Sea region: Regional and global lessons

Date

11/05/2017

Lecturers

Prof. Hezi Gildor - Institute of Earth Sciences, The Hebrew University of Jerusalem

Abstract

The Red Sea is connected to the Indian Ocean via a narrow and shallow strait. It is extremely sensitive to climatic changes, including sea-level variations and changes in atmospheric conditions, and therefore it is an ideal place to study climate variability. We used an ocean general circulation model in conjunction with proxy records to investigate regional and global climate changes during the Last Glacial Maximum (LGM), during the Holocene, and during MIS 5e . Our results for the LGM show that the conditions within the Red Sea are very sensitive to sea level reduction and there is only a mild atmospheric impact. The best correlation between the model results and reconstructed conditions exists when the water depth at the Hanish Sill is ~33, which would be effected by a sea level lowering of ~105m. A local relative sea level reduction of ~105m also closely agrees with the inference of the LGM low sea level at the location of the sill based on the ICE-5G (VM2) model. During the Holocene and MIS 5e, the Red Sea was characterized by high sea level and extreme changes in the hydrological cycle at both Mediterranean and the Monsoons climatic domains. Therefore, the Red Sea was sensitive to changes in atmospheric conditions, and it only showed a relatively mild response to sea level change. Sea surface temperature reconstructed from proxy records and our model results suggest prevailing humid conditions during early Holocene and arid conditions during late Holocene. The gradual decline in Red Sea temperature between these two time periods suggests a gradual decline in the summer monsoon strength. Because Monsoon-driven changes in the exchange flow through the Strait of Bab el Mandab affected the crenarchaea population structure, their molecular fossil distribution in the sediments of the Red Sea potentially provides an index for the summer monsoon strength during the Holocene.

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