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| Titel |
Large-Ensemble modeling of last deglacial and future variations of the Antarctic Ice Sheet |
| VerfasserIn |
David Pollard, Robert DeConto, Won Chang, Patrick Applegate, Murali Haran |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106066
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| Publikation (Nr.) |
 EGU/EGU2015-5717.pdf |
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| Zusammenfassung |
| Recent observations of thinning and retreat of the Pine Island and Thwaites
Glaciers identify the Amundsen Sea Embayment (ASE) sector of West Antarctica as
particularly vulnerable to future climate change. To date, most future modeling
of these glaciers has been calibrated using recent and modern observations.
As an alternate approach, we apply a hybrid 3-D ice sheet-shelf model to the
last deglacial retreat of Antarctica, making use of geologic data from
~20,000 years BP to present, focusing on the ASE but including other sectors
of Antarctica.
Following several recent ice-sheet studies, we use Large-Ensemble statistical
techniques, performing sets of ~500 to 1000 runs with varying model parameters.
The model is run for the last 40 kyrs on 10 to 20-km grids, both on continental
domains and also on nested domains over West Antarctica. Various types
of objective scores for each run are calculated using reconstructed past
grounding lines, relative sea level records, measured uplift rates, and
cosmogenic elevation-age data. Runs are extended into the future few millennia
using RCP scenarios. The goal is to produce calibrated probabilistic ranges of
model parameter values and quantified envelopes of future ice retreat.
Preliminary results are presented for Large Ensembles with (i) Latin HyperCube
sampling in high-dimensional parameter space, using statistical emulators
and Markov Chain Monte Carlo techniques, and (ii) dense "factorial" sampling
with a smaller number of parameters. Different ways of combining the types
of scores listed above are explored. One robust conclusion is that for the
warmer future RCP scenarios, most reasonable parameter combinations
produce retreat deep into the West Antarctic interior. Recently proposed
mechanisms of hydrofracturing and ice-cliff failure accelerate future
West Antarctic retreat, and later produce retreat into East Antarctic basins. |
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