Regional seesaw between the North Atlantic and Nordic Seas during the last glacial abrupt climate events

Mélanie Wary,Mélanie Wary,Mélanie Wary,Jean Jouzel,Jean Jouzel,Valérie Masson-Delmotte,Valérie Masson-Delmotte,Valérie Masson-Delmotte,Valérie Masson-Delmotte,Valérie Masson-Delmotte,Jens Matthiessen,Jena Zumaque,Linda Rossignol,Jean Jouzel,Jean Jouzel,Jean Jouzel,Didier Swingedouw,Didier Swingedouw,Didier Swingedouw,Frédérique Eynaud,Frédérique Eynaud,Frédérique Eynaud,Catherine Kissel,Catherine Kissel,Catherine Kissel,Catherine Kissel,Catherine Kissel

doi:10.5194/cp-13-729-2017

Abstract

Abstract. Dansgaard–Oeschger oscillations constitute one of the most enigmatic features of the last glacial cycle. Their cold atmospheric phases have been commonly associated with cold sea-surface temperatures and expansion of sea ice in the North Atlantic and adjacent seas. Here, based on dinocyst analyses from the 48–30 ka interval of four sediment cores from the northern Northeast Atlantic and southern Norwegian Sea, we provide direct and quantitative evidence of a regional paradoxical seesaw pattern: cold Greenland and North Atlantic phases coincide with warmer sea-surface conditions and shorter seasonal sea-ice cover durations in the Norwegian Sea as compared to warm phases. Combined with additional palaeorecords and multi-model hosing simulations, our results suggest that during cold Greenland phases, reduced Atlantic meridional overturning circulation and cold North Atlantic sea-surface conditions were accompanied by the subsurface propagation of warm Atlantic waters that re-emerged in the Nordic Seas and provided moisture towards Greenland summit.

Highlights

The last glacial cycle has been punctuated by abrupt climatic variations strongly imprinted in Greenland ice core records where they translate into millennial oscillations between cold (Greenland stadial, GS) and warm (Greenland interstadial, GI) atmospheric phases (e.g., North GreenlandIce Core Project members, 2004)
Cold sea-surface temperatures (SSTs) and expansion of sea ice during GS were mainly inferred from indirect marine proxy records, such as significant increases in ice-rafted debris concentration or variations in the relative abundance and oxygen isotopic content of the polar planktonic foraminifera Neogloboquadrina pachyderma sinistral coiling (NPS) (Bond and Lotti, 1995; Dokken and Jansen, 1999; Rasmussen and Thomsen, 2004; Dokken et al, 2013) whose preferential depth habitat lies from a few tens of metres to around 250 m water depth in the Nordic Seas (e.g. Simstich et al, 2003)
Our sea-surface reconstructions reveal contrasted responses of the southeastern Nordic Seas compared to the northeastern Atlantic (Fig. 2, Tables 1, 2 and 3)

Summary

Introduction

They are tightly linked to pan-North Atlantic ice-sheet dynamic that manifests itself by cyclic iceberg releases concomitant with GS (Bond and Lotti, 1995). Cold sea-surface temperatures (SSTs) and expansion of sea ice during GS were mainly inferred from indirect marine proxy records, such as significant increases in ice-rafted debris concentration or variations in the relative abundance and oxygen isotopic content of the polar planktonic foraminifera Neogloboquadrina pachyderma sinistral coiling (NPS) (Bond and Lotti, 1995; Dokken and Jansen, 1999; Rasmussen and Thomsen, 2004; Dokken et al, 2013) whose preferential depth habitat lies from a few tens of metres to around 250 m water depth in the Nordic Seas The occurrence of a pycnocline separating this cold and sea-ice-covered surface layer from warmer Atlantic subsurface waters have been reported during GS on the basis of these and other planktonic

Methods

Results

Conclusion