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| Titel |
Parallelisms between sea surface temperature changes in the western tropical Atlantic (Guiana Basin) and high latitude climate signals over the last 140 000 years |
| VerfasserIn |
O. Rama-Corredor, B. Martrat, J. O. Grimalt, G. E. López-Otalvaro, J. A. Flores, F. Sierro |
| 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 ; 11, no. 10 ; Nr. 11, no. 10 (2015-10-06), S.1297-1311 |
| Datensatznummer |
250117431
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| Publikation (Nr.) |
 copernicus.org/cp-11-1297-2015.pdf |
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| Zusammenfassung |
Sea surface temperatures (SST) in the Guiana Basin over the last 140 ka were
obtained by measuring the C37 alkenone unsaturation index
Uk'37 in the sediment core MD03-2616 (7° N,
53° W). The resulting data set is unique in the western
tropical Atlantic region for this period. The SSTs range from
25.1 to 28.9 °C, i.e.
glacial–interglacial amplitude of 3.8 °C, which is in the
range of change of other tropical areas.
During the last two interglacial stages (marine isotope stages; MIS1 and MIS5e) and warm long
interstadials (MIS5d-a), a rapid transmission of climate variability from
Arctic–tropical latitudes is recorded. During these periods, the
MD03-2616 SSTs show a conspicuous parallelism with temperature changes
observed in Greenland and SST records of North Atlantic mid-latitude cores
(Iberian Margin 38° N, Martrat et al., 2007).
The last deglaciation in the Guiana Basin is particularly revealing. MIS2
stands out as the coldest period of the interval analysed. The events
recorded in Guiana parallel northern latitude events such as the
Bølling–Allerød warming and the Younger Dryas cooling which ensued.
These oscillations were previously documented in the δ18O of
the Sajama tropical ice core (Bolivia) and are present in Guiana, with rates
of ca. 6 °C ka−1 and changes of over 2 °C.
During the glacial interval, significant abrupt variability is observed,
e.g. oscillations of 0.5–1.2 °C during MIS3, which is about
30 % of the maximum glacial–interglacial SST change. In the MD03-2616
record, it is possible to unambiguously identify either the Dansgaard–Oeschger
oscillations described in northern latitudes or the SST drops associated
with the Heinrich events characteristic of North Atlantic records. Although
these events form the background of the climate variability observed, what
truly shapes SSTs in the Guiana Basin is a long-term tropical response to
precessional changes, which is modulated in the opposite way to Northern
Hemisphere variability. This lack of synchrony is consistent with other
tropical records in locations to the north or south of the Guiana Basin and
evidences an Arctic–tropical decoupling when a substantial reduction in
the Atlantic meridional overturning circulation (AMOC) takes place. |
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