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Highly variable Pliocene sea surface conditions in the Norwegian Sea.

Bachem, Paul E. and Risebrobakken, Bjørg and De Schepper, Stijn and McClymont, Erin L. (2017) 'Highly variable Pliocene sea surface conditions in the Norwegian Sea.', Climate of the past., 13 (9). pp. 1153-1168.

Abstract

The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial–interglacial variability. Here, we present high-resolution records of sea surface temperature (SST) and ice-rafted debris (IRD) in the Norwegian Sea from 5.32 to 3.14 Ma, providing evidence that the Pliocene surface conditions of the Norwegian Sea underwent a series of transitions in response to orbital forcing and gateway changes. Average SSTs are 2 °C above the regional Holocene mean, with notable variability on millennial to orbital timescales. Both gradual changes and threshold effects are proposed for the progression of regional climate towards the Late Pliocene intensification of Northern Hemisphere glaciation. Cooling from 4.5 to 4.3 Ma may be linked to the onset of poleward flow through the Bering Strait. This cooling was further intensified by a period of cool summers due to weak obliquity forcing. A 7 °C warming of the Norwegian Sea at 4.0 Ma suggests a major increase in northward heat transport from the North Atlantic, leading to an enhanced zonal SST gradient in the Nordic Seas, which may be linked to the expansion of sea ice in the Arctic and Nordic Seas. A warm Norwegian Sea and enhanced zonal temperature gradient between 4.0 and 3.6 Ma may have been a priming factor for increased glaciation around the Nordic Seas due to enhanced evaporation and precipitation at high northern latitudes.

Item Type:Article
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.5194/cp-13-1153-2017
Publisher statement:© Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License.
Date accepted:10 July 2017
Date deposited:18 September 2017
Date of first online publication:11 September 2017
Date first made open access:No date available

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