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| Titel |
A new chronology and probabilistic assessment of sea-level variability over five glacial cycles |
| VerfasserIn |
Katharine M. Grant, Eelco J. Rohling, Christopher Bronk Ramsey, Hai Cheng, R. Lawrence Edwards, Fabio Florindo, David Heslop, Fabrizio Marra, Andrew P. Roberts, Mark E. Tamisiea, Felicity Williams |
| 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 |
250101121
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| Publikation (Nr.) |
 EGU/EGU2015-1979.pdf |
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| Zusammenfassung |
| On geological timescales, changes in sea level give an indication of the global glaciation
state. To fully portray how Earth’s glaciation state varied in the past, we need to
consider the timing and amplitude of sea-level changes during both glacial and
interglacial intervals. Ideally, we also need to consider such changes over several
glacial-interglacial cycles, so that i) any systematic sea-level/ice-volume relationships
can be discerned, and ii) more reliable estimates of sea-level change rates under
different boundary conditions can be determined. While an increasing number of
well-dated sea-level records exists for periods within the last glacial cycle, older time
intervals are much less represented. For example, available reconstructions of sea level
prior to the last interglacial tend to be discontinuous or of low resolution, contain
large sea-level uncertainties, or have orbitally tuned chronologies that are biased
by assumptions about climate: ice-volume phasings. To address these issues, we
have developed a robust, radiometrically constrained timescale for continuous and
centennial-resolution records of sea level and rates of sea-level change, over the last five
glacial cycles (~500,000 years). Our method is based on synchronisation of Red
Sea dust and relative sea-level (RSL) records to a speleothem δ18O record from
Sanbao Cave (China). We have also used Bayesian and Monte Carlo-style methods
to assess chronological and sea-level uncertainties, which has resulted in the first
probabilistic records of sea level and sea-level change rates for periods before the last
interglacial. This provides an opportunity for detailed comparisons with existing
sea-level/ice-volume reconstructions, and for validating models of sea-level rise and ice-sheet
dynamics. Finally, to illustrate an implication of our new sea-level records, we
explored the relationship between natural (pre-anthropogenic forcing) sea-level
rise rates and ‘glaciation state’, where the latter is defined as the past relative to
present-day global ice volume. Our results suggest that maximum sea-level rise rates
remained below 2 m per century following periods with up to twice present-day ice
volumes, while substantially higher rise rates were attained for greater ice volumes. |
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