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| Titel |
Sea surface temperatures in the North Atlantic Ocean from 30ka to 10ka |
| VerfasserIn |
Kerr Barrack, Rosanna Greenop, Andrea Burke, Stephen Barker, Thomas Chalk, Anya Crocker |
| 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 |
250122164
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| Publikation (Nr.) |
 EGU/EGU2016-1121.pdf |
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| Zusammenfassung |
| Some of the most striking features of the Late Pleistocene interval are the rapid changes in
climate between warmer interstadial and cold stadial periods which, when coupled,
are termed Dansgaard-Oeschger (D-O) events. This shift between warm and cold
climates has been interpreted to result from changes in the thermohaline circulation
(Broecker et al., 1985) triggered by, for instance, freshwater input from the collapse of
the Laurentide ice sheet (Zahn et al., 1997). However, a recent study suggests that
major ice rafting events cannot be the ‘trigger’ for the centennial to millennial scale
cooling events identified over the past 500kyr (Barker at al., 2015). Polar planktic
foraminiferal and lithogenic/terrigenous grain counts reveal that the southward
migration of the polar front occurs before the deposition of ice rafted debris and
therefore the rafting of ice during stadial periods. Based upon this evidence, Barker et
al. suggest that the transition to a stadial state is a non-linear response to gradual
cooling in the region. In order to test this hypothesis, our study reconstructs sea
surface temperature across D-O events and the deglaciation in the North Atlantic
between 30ka and 10ka using Mg/ Ca paleothermometry in Globigerina bulloides
at ODP Sites 980 and 983 (the same sites as used in Barker et al., 2015) with an
average sampling resolution of 300 years. With our new record we evaluate the timing
of surface ocean temperature change, frontal shift movement, and ice rafting to
investigate variations in the temperature gradient across the polar front over D-O
events.
References:
Barker, S., Chen, J., Gong, X., Jonkers, L., Knorr, G., Thornalley, D., 2015.
Icebergs not the trigger for North Atlantic cold events. Nature, 520(7547),
pp.333-336.
Broecker, W.S., Peteer, D.M., Rind, D., 1985. Does the ocean-atmosphere system
have more than one stable mode of operation? Nature, 315 (6014), pp.21-26.
Zahn, R., Schönfeld, J., Kudrass, H.-R., Park, M.-H., Erlenkeuser, H., Grootes,
P, 1997. Thermohaline instability in the North Atlantic during meltwater events:
Stable isotope and ice-rafted detritus records from Core SO75-26KL, Portuguese
Margin. Paleoceanography, 12(5), pp.696–710. |
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