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| Titel |
Observationally constrained projections of Antarctic ice sheet instability |
| VerfasserIn |
Tamsin Edwards, Catherine Ritz, Gael Durand, Anthony Payne, Vincent Peyaud, Richard Hindmarsh |
| 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 |
250113839
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| Publikation (Nr.) |
 EGU/EGU2015-14074.pdf |
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| Zusammenfassung |
| Large parts of the Antarctic ice sheet lie on bedrock below sea level and may be vulnerable to
a positive feedback known as Marine Ice Sheet Instability (MISI), a self-sustaining retreat of
the grounding line triggered by oceanic or atmospheric changes. There is growing evidence
MISI may be underway throughout the Amundsen Sea Embayment (ASE) of West
Antarctica, induced by circulation of warm Circumpolar Deep Water. If this retreat is
sustained the region could contribute up to 1-2Âm to global mean sea level, and if triggered in
other areas the potential contribution to sea level on centennial to millennial timescales could
be two to three times greater.
However, physically plausible projections of Antarctic MISI are challenging: numerical
ice sheet models are too low in spatial resolution to resolve grounding line processes or else
too computationally expensive to assess modelling uncertainties, and no dynamical models
exist of the ocean-atmosphere-ice sheet system. Furthermore, previous numerical ice sheet
model projections for Antarctica have not been calibrated with observations, which can
reduce uncertainties.
Here we estimate the probability of dynamic mass loss in the event of MISI under a
medium climate scenario, assessing 16 modelling uncertainties and calibrating the
projections with observed mass losses in the ASE from 1992-2011. We project losses of up to
30 cm sea level equivalent (SLE) by 2100 and 72 cm SLE by 2200 (95% credibility interval:
CI). Our results are substantially lower than previous estimates. The ASE sustains substantial
losses, 83% of the continental total by 2100 and 67% by 2200 (95% CI), but in other regions
losses are limited by ice dynamical theory, observations, or a lack of projected triggers. |
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