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| Titel |
Deglacial ice sheet meltdown: orbital pacemaking and CO2 effects |
| VerfasserIn |
M. Heinemann, A. Timmermann, O. Elison Timm, F. Saito, A. Abe-Ouchi |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2014-08-27), S.1567-1579 |
| Datensatznummer |
250117028
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| Publikation (Nr.) |
 copernicus.org/cp-10-1567-2014.pdf |
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| Zusammenfassung |
| One hundred thousand years of ice sheet buildup came to a rapid end
∼25–10 thousand years before present (ka BP), when ice sheets
receded quickly and multi-proxy reconstructed global mean surface
temperatures rose by ∼3–5 °C. It still remains unresolved
whether insolation changes due to variations of earth's tilt and orbit were
sufficient to terminate glacial conditions. Using a coupled three-dimensional
climate–ice sheet model, we simulate the climate and Northern Hemisphere ice
sheet evolution from 78 ka BP to 0 ka BP in good agreement with sea level
and ice topography reconstructions. Based on this simulation and a series of
deglacial sensitivity experiments with individually varying orbital
parameters and prescribed CO2, we find that enhanced calving led to a
slowdown of ice sheet growth as early as ∼8 ka prior to the Last
Glacial Maximum (LGM). The glacial termination was then initiated by enhanced
ablation due to increasing obliquity and precession, in agreement with the
Milankovitch theory. However, our results also support the notion that the
∼100 ppmv rise of atmospheric CO2 after ∼18 ka BP was a
key contributor to the deglaciation. Without it, the present-day ice volume
would be comparable to that of the LGM and global mean temperatures would be
about 3 °C lower than today. We further demonstrate that neither
orbital forcing nor rising CO2 concentrations alone were sufficient to
complete the deglaciation. |
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