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| Titel |
Mean ocean temperature change over the last glacial transition based on atmospheric changes in heavy noble mixing ratios |
| VerfasserIn |
Bernhard Bereiter, Jeff Severinghaus, Sarah Shackleton, Daniel Baggenstos, Kenji Kawamura |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250127148
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| Publikation (Nr.) |
 EGU/EGU2016-6986.pdf |
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| Zusammenfassung |
| On paleo-climatic timescales heavy noble gases (Krypton and Xenon) are passively
cycled through the atmosphere-ocean system without seeing any significant sink or
source. Since the solubility in water of each gas species is characterized by a specific
temperature dependency, mixing ratios in the atmosphere change with changing
ocean temperatures. In this study, we use this fact to reconstruct mean global ocean
temperatures (MOT) over the course of the last glacial transition based on measurements
of trapped air in the WAIS Divide ice core. We analyzed 70 ice samples with a
recently developed method which determines the isotopic ratios of N2, Ar, Kr (and
in some cases also of Xe, though with less precision) and the elemental ratios of
Kr/N2, Xe/N2 and Xe/Kr. We use the isotope ratios to correct the elemental ratios
for gravitational enrichment in the firn column. The corrected elemental ratios are
then used in a simple box model to reconstruct MOT. The three elemental ratio
pairs are first interpreted as independent measures of MOT and then combined to a
single “best-estimate” MOT record with an average uncertainty of 0.27∘C. We find
a clear link to Antarctic temperatures and a LGM-Holocene change in MOT of
2.4∘C. This value is in good agreement with results from marine sediment cores
(which, however, have an uncertainty of 1∘C). Our record provides an unprecedented
constrain on ocean heat uptake over the last glacial transition and therefore gives
new insights in the mechanisms underlying long term ocean heat fluxes. To our
knowledge, this is the first time that MOT has been reconstructed in such great detail. |
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