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  4. Antarctic ice-sheet expansions in the Middle Miocene and Pliocene
 
Zitierlink URN
https://nbn-resolving.de/urn:nbn:de:gbv:46-diss000112917

Antarctic ice-sheet expansions in the Middle Miocene and Pliocene

Veröffentlichungsdatum
2008-12-12
Autoren
Langebroek, Petra  
Betreuer
Schulz, Michael  
Gutachter
Tiedemann, Ralf  
Zusammenfassung
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.
Schlagwörter
Antarctic ice sheet

; 

modeling

; 

CO2

; 

insolation

; 

Middle Miocene
Institution
Universität Bremen  
Fachbereich
Fachbereich 05: Geowissenschaften (FB 05)  
Dokumenttyp
Dissertation
Zweitveröffentlichung
Nein
Sprache
Englisch
Dateien
Lade...
Vorschaubild
Name

00011291.pdf

Size

4.3 MB

Format

Adobe PDF

Checksum

(MD5):991f17814a281dc3c2dc37192e08b41b

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