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| Titel |
Antarctic glaciations under Pliocene climate conditions from numerical modeling and compilation of local field-based reconstructions |
| VerfasserIn |
Jorge Bernales, Irina Rogozhina, Ralf Greve |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086434
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| Publikation (Nr.) |
 EGU/EGU2014-297.pdf |
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| Zusammenfassung |
| The mid-Pliocene (3.15 to 2.85 million years before present) is the most recent period in
Earth’s history when temperatures and CO2 concentrations were likely sustainedly higher
than pre-industrial values. Furthermore, the positions of the continents and their sea-land
distributions had already reached their present configuration, sharing some similarities with
today’s patterns of ocean circulation and vegetation distributions. Although significant
differences exist —such as a peak sea level that could have been 22 ± 10 m higher than it is
today and sea surface temperatures particularly warmer at higher latitudes, mid-Pliocene has
been identified as an ideal interval for studying the climate system under conditions similar to
those projected for the end of this century. Among the sources of uncertainty in the
projections, the response of the Antarctic ice sheet (AIS) to warmer-than-today
conditions seems to play a central role. Therefore, a better understanding of AIS’s
behavior during periods like the mid-Pliocene will provide valuable information that
could help improve future predictions. For this purpose, we have compiled a wide
range of local field-based reconstructions of the ice-sheet margin from Pliocene
sediments (with the inclusions of organic matters such as, for instance, diatoms or
palynoflora, or ice rafted debris), geochemical records, volcanic ashes and rocks, and
geomorphology, and designed numerical experiments of the AIS dynamics during the
mid-Pliocene warm period using the large-scale polythermal ice sheet-shelf model
SICOPOLIS (Greve, 1997[1]; Sato and Greve, 2012[2]). The model is run with a
horizontal resolution of 40 x 40 km by the climatology obtained from the PlioMIP
Atmosphere Ocean Global Circulation Model experiments (Dolan et al., 2012[3]).
Parameters of the AIS model (e.g.ice calving, sub-ice shelf and surface ice melt,
basal sliding, etc.) have initially been estimated using ice-sheet simulations driven
by the present-day climate and ocean conditions and calibrated against available
remote-sensed and in-situ observations. In our Pliocene experiments, we employ alternative
parameterizations of sub-ice shelf and ice surface melting processes to test the
likelihood of numerous controversial theories and reconstructions arguing for or against
significant retreat of the East Antarctic ice sheet from the coasts (locally up to 450
km) in the mid-Pliocene. Finally, we assess the sensitivity of the modeled West
Antarctic/Antarctic Peninsula ice geometry to the above parameters and emphasize a
crucial role of surface mass balance model parameters in modeling the Pliocene
ice sheet configuration in agreement with existing reconstructions on a regional
scale.
References
[1]Greve, R. (1997). Application of a polythermal three-dimensional ice sheet
model to the Greenland ice sheet: response to steady-state and transient climate
scenarios. Journal of Climate, 10(5), 901-918.
[2]Sato, T., and Greve, R. (2012). Sensitivity experiments for the Antarctic
ice sheet with varied sub-ice-shelf melting rates. Annals of Glaciology, 53(60),
221-228.
[3]Dolan, A. M., Koenig, S. J., Hill, D. J., Haywood, A. M., and
DeConto, R. M. (2012). Pliocene Ice Sheet Modelling Intercomparison
Project (PLISMIP)-experimental design. Geoscientific Model Development, 5(4),
963-974. |
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