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Citation link: http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000112917
00011291.pdf
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Antarctic ice-sheet expansions in the Middle Miocene and Pliocene


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Other Titles: Antarctic ice-sheet expansions in the Middle Miocene and Pliocene
Authors: Langebroek, Petra 
Supervisor: Schulz, Michael
1. Expert: Schulz, Michael
2. Expert: Tiedemann, Ralf
Abstract: 
The ice sheet-climate model developed in this study describes the Antarctic ice sheet. It is forced by energy and mass balances and includes oxygen isotopes as a passive tracer.Simulating the Middle Miocene climate transition showed that a decrease in atmospheric CO2, crossing a threshold of about 400 ppm, followed by a minimum in summer insolation, initiated a large-scale ice-sheet expansion.Experiments further confirm the validity of the often applied ratio of a 1 permille increase in oxygen-isotope composition for a global sea-level lowering of 100 m. For the mid-Pliocene, the ice-sheet component was forced by temperatures and accumulation rates from a comprehensive climate model. The closure of the Panamanian gateway in the mid-Pliocene was found to induce an intensification of the meridional circulation with a cooling over Antarctica as result. In turn, this cooling forced the Antarctic ice-sheet to expand. From the examples discussed in this study it can be concluded that changes in temperature, due to atmospheric CO2 as well as due to tectonic forcing, have a large impact on the extent of the Antarctic ice sheet.
Keywords: Antarctic ice sheet; modeling; CO2; insolation; Middle Miocene
Issue Date: 12-Dec-2008
Type: Dissertation
URN: urn:nbn:de:gbv:46-diss000112917
Institution: Universität Bremen 
Faculty: FB5 Geowissenschaften 
Appears in Collections:Dissertationen

  

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