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| Titel |
Long-term variations in Iceland–Scotland overflow strength during the Holocene |
| VerfasserIn |
D. J. R. Thornalley, M. Blaschek, F. J. Davies, S. Praetorius, D. W. Oppo, J. F. McManus, I. R. Hall, H. Kleiven, H. Renssen, I. N. McCave |
| 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 (2013-09-03), S.2073-2084 |
| Datensatznummer |
250085218
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| Publikation (Nr.) |
 copernicus.org/cp-9-2073-2013.pdf |
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| Zusammenfassung |
| The overflow of deep water from the Nordic seas into the North Atlantic plays
a critical role in global ocean circulation and climate. Approximately half
of this overflow occurs via the Iceland–Scotland (I–S) overflow, yet the
history of its strength throughout the Holocene (~ 0–11 700 yr ago,
ka) is poorly constrained, with previous studies presenting apparently
contradictory evidence regarding its long-term variability. Here, we provide
a comprehensive reconstruction of I–S overflow strength throughout the
Holocene using sediment grain size data from a depth transect of 13 cores
from the Iceland Basin. Our data are consistent with the hypothesis that the
main axis of the I–S overflow on the Iceland slope was shallower during the
early Holocene, deepening to its present depth by ~ 7 ka. Our results
also reveal weaker I–S overflow during the early and late Holocene, with
maximum overflow strength occurring at ~ 7 ka, the time of a regional
climate thermal maximum. Climate model simulations suggest a shoaling of deep
convection in the Nordic seas during the early and late Holocene, consistent
with our evidence for weaker I–S overflow during these intervals. Whereas the
reduction in I–S overflow strength during the early Holocene likely resulted
from melting remnant glacial ice sheets, the decline throughout the last
7000 yr was caused by an orbitally induced increase in the amount of Arctic
sea ice entering the Nordic seas. Although the flux of Arctic sea ice to the
Nordic seas is expected to decrease throughout the next century, model
simulations predict that under high emissions scenarios, competing effects,
such as warmer sea surface temperatures in the Nordic seas, will result in
reduced deep convection, likely driving a weaker I–S overflow. |
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