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| Titel |
Mechanisms and time scales of glacial inception simulated with an Earth system model of intermediate complexity |
| VerfasserIn |
R. Calov, A. Ganopolski, C. Kubatzki, M. Claussen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 5, no. 2 ; Nr. 5, no. 2 (2009-06-25), S.245-258 |
| Datensatznummer |
250002400
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| Publikation (Nr.) |
 copernicus.org/cp-5-245-2009.pdf |
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| Zusammenfassung |
| We investigate glacial inception and glacial thresholds in the
climate-cryosphere system utilising the Earth system model of
intermediate complexity CLIMBER-2, which includes modules for
atmosphere, terrestrial vegetation, ocean and interactive ice
sheets. The latter are described by the three-dimensional polythermal
ice-sheet model SICOPOLIS. A bifurcation which represents glacial
inception is analysed with two different model setups: one setup with
dynamical ice-sheet model and another setup without it. The respective
glacial thresholds differ in terms of maximum boreal summer insolation
at 65° N (hereafter referred as Milankovitch forcing
(MF)). The glacial threshold of the configuration without ice-sheet
dynamics corresponds to a much lower value of MF compared to the
full model. If MF attains values only slightly below the
aforementioned threshold there is fast transient response. Depending
on the value of MF relative to the glacial threshold, the transient
response time of inland-ice volume in the model configuration with
ice-sheet dynamics ranges from 10 000 to 100 000 years. Due to these
long response times, a glacial threshold obtained in an equilibrium
simulation is not directly applicable to the transient response of
the climate-cryosphere system to time-dependent orbital forcing. It
is demonstrated that in transient simulations just crossing
of the glacial threshold does not imply large-scale
glaciation of the Northern Hemisphere. We found that in transient
simulations MF has to drop well below the glacial threshold determined
in an equilibrium simulation to initiate glacial inception. Finally,
we show that the asynchronous coupling between climate and inland-ice
components allows one sufficient realistic simulation of glacial inception
and, at the same time, a considerable reduction of computational costs. |
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