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| Titel |
Holocene climate variations in the western Antarctic Peninsula: evidence for sea ice extent predominantly controlled by changes in insolation and ENSO variability |
| VerfasserIn |
J. Etourneau, L. G. Collins, V. Willmott, J.-H. Kim, L. Barbara, A. Leventer, S. Schouten, J. S. Sinninghe Damsté, A. Bianchini, V. Klein, X. Crosta, G. Massé |
| 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. 4 ; Nr. 9, no. 4 (2013-07-05), S.1431-1446 |
| Datensatznummer |
250018084
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| Publikation (Nr.) |
 copernicus.org/cp-9-1431-2013.pdf |
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| Zusammenfassung |
| The West Antarctic ice sheet is particularly sensitive to
global warming and its evolution and impact on global climate over the next
few decades remains difficult to predict. In this context, investigating
past sea ice conditions around Antarctica is of primary importance. Here, we
document changes in sea ice presence, upper water column temperatures (0–200 m)
and primary productivity over the last 9000 yr BP (before present) in
the western Antarctic Peninsula (WAP) margin from a sedimentary core
collected in the Palmer Deep Basin. Employing a multi-proxy approach, based
on the combination of two biomarkers proxies (highly branched isoprenoid
(HBI) alkenes for sea ice and TEX86L for temperature) and
micropaleontological data (diatom assemblages), we derived new Holocene
records of sea ice conditions and upper water column temperatures. The early
Holocene (9000–7000 yr BP) was characterized by a cooling phase with a
short sea ice season. During the mid-Holocene (~7000–3800 yr BP),
local climate evolved towards slightly colder conditions and a
prominent extension of the sea ice season occurred, promoting a favorable
environment for intensive diatom growth. The late Holocene (the last
~2100 yr) was characterized by warmer temperatures and
increased sea ice presence, accompanied by reduced local primary
productivity, likely in response to a shorter growing season compared to the
early or mid-Holocene. The gradual increase in annual sea ice duration over
the last 7000 yr might have been influenced by decreasing mean annual
and spring insolation, despite increasing summer insolation. We postulate
that, in addition to precessional changes in insolation, seasonal
variability, via changes in the strength of the circumpolar Westerlies and
upwelling activity, was further amplified by the increasing
frequency/amplitude of the El Niño–Southern Oscillation (ENSO). However,
between 3800 and 2100 yr BP, the lack of correlation between ENSO and
climate variability in the WAP suggests that other climatic factors might
have been more important in controlling WAP climate at this time. |
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