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| Titel |
An assessment of key model parametric uncertainties in projections of Greenland Ice Sheet behavior |
| VerfasserIn |
P. J. Applegate, N. Kirchner, E. J. Stone, K. Keller, R. Greve |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 6, no. 3 ; Nr. 6, no. 3 (2012-05-30), S.589-606 |
| Datensatznummer |
250003593
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| Publikation (Nr.) |
 copernicus.org/tc-6-589-2012.pdf |
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| Zusammenfassung |
| Lack of knowledge about the values of ice sheet model input parameters
introduces substantial uncertainty into projections of Greenland Ice Sheet
contributions to future sea level rise. Computer models of ice sheet
behavior provide one of several means of estimating future sea level rise
due to mass loss from ice sheets. Such models have many input parameters
whose values are not well known. Recent studies have investigated the
effects of these parameters on model output, but the range of potential
future sea level increases due to model parametric uncertainty has not been
characterized. Here, we demonstrate that this range is large, using a
100-member perturbed-physics ensemble with the SICOPOLIS ice sheet model.
Each model run is spun up over 125 000 yr using geological forcings and
subsequently driven into the future using an asymptotically increasing air
temperature anomaly curve. All modeled ice sheets lose mass after 2005 AD.
Parameters controlling surface melt dominate the model response to
temperature change. After culling the ensemble to include only members that
give reasonable ice volumes in 2005 AD, the range of projected sea level
rise values in 2100 AD is ~40 % or more of the median. Data on past
ice sheet behavior can help reduce this uncertainty, but none of our
ensemble members produces a reasonable ice volume change during the
mid-Holocene, relative to the present. This problem suggests that the
model's exponential relation between temperature and precipitation does not
hold during the Holocene, or that the central-Greenland temperature forcing
curve used to drive the model is not representative of conditions around the
ice margin at this time (among other possibilities). Our simulations also
lack certain observed physical processes that may tend to enhance the real
ice sheet's response. Regardless, this work has implications for other
studies that use ice sheet models to project or hindcast the behavior of the
Greenland Ice Sheet. |
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