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| Titel |
Why could ice ages be unpredictable? |
| VerfasserIn |
M. Crucifix |
| 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 ; 9, no. 5 ; Nr. 9, no. 5 (2013-10-09), S.2253-2267 |
| Datensatznummer |
250085228
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| Publikation (Nr.) |
 copernicus.org/cp-9-2253-2013.pdf |
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| Zusammenfassung |
It is commonly accepted that the variations of Earth's orbit and
obliquity control the timing of Pleistocene glacial–interglacial
cycles. Evidence comes from power spectrum analysis of
palaeoclimate records and from inspection of the timing of glacial
and deglacial transitions. However, we do not know how tight this
control is. Is it, for example, conceivable that random climatic
fluctuations could cause a delay in deglaciation, bad enough to
skip a full precession or obliquity cycle and subsequently modify
the sequence of ice ages?
To address this question, seven previously published conceptual
models of ice ages are analysed by reference to the notion of
generalised synchronisation. Insight is being gained by comparing
the effects of the astronomical forcing with idealised forcings
composed of only one or two periodic components. In general, the
richness of the astronomical forcing allows for synchronisation
over a wider range of parameters, compared to periodic forcing.
Hence, glacial cycles may conceivably have remained paced by the
astronomical forcing throughout the Pleistocene.
However, all the models examined here show regimes of strong
structural dependence on parameters.
This means that small variations in parameters
or random fluctuations may cause significant shifts in the
succession of ice ages.
Whether the actual system actually resides
in such a regime depends on the amplitude of the effects associated with
the astronomical forcing, which significantly differ across the
different models studied here. The possibility of synchronisation
on eccentricity is also discussed and it is shown that a high
Rayleigh number on eccentricity, as recently found in observations,
is no guarantee of reliable synchronisation. |
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