Holocene changes in sea-ice cover and polynya formation along the eastern North Greenland shelf: New insights from biomarker records

Nicole Syring,Ruediger Stein,Kirsten Fahl,Maximilian Vahlenkamp,Marc Zehnich,Robert F Spielhagen,Frank Niessen

doi:10.1016/j.quascirev.2020.106173

Abstract

Understanding the processes controlling the natural variability of sea ice in the Arctic, one of the most dynamic components of the climate system, can help to constrain the effects of future climate change in this highly sensitive area. For the first time, a high-resolution biomarker study was carried out to reconstruct past sea-ice variability off eastern North Greenland. This area is strongly influenced by cold surface waters and drift ice transported via the East Greenland Current, meltwater pulses from the outlet glaciers of the Northeast Greenland Ice Stream and the build-up of landfast ice. The well-dated Holocene sedimentary section of Core PS93/025 provides insights into variations of the sea-ice conditions (regional and local sea-ice signal), oceanic and atmospheric circulation and the biotic response to these changes. These biomarker records show a reduced to variable sea-ice cover during the early Holocene between 10.2 and 9.3 ka, followed by a steady increase in sea-ice conditions during the mid Holocene. During the last 5–6 ka, sea-ice conditions remained more stable representing a seasonal to marginal sea-ice situation. Based on our biomarker records, stable sea-ice edge conditions, with a fully developed polynya situation occurred since the last 1 ka.

Highlights

Chronology The age model is based on 19 accelerator mass spectrometry (AMS) 14C ages measured on macro- and microfossil species, including benthic foraminifera, planktic foraminifera (Neogloboquadrina pachyderma), bivalves, and scaphopods from GKG Core PS93/025e1 and Kastenlot Core PS93/025e2 (Table 1)
Single records of the bulk parameters versus depth are available in the and b-sitosterol) of Core PS93/025 vary more or less synchronously over the entire Holocene record, which can be subdivided into three main intervals (Fig. 4)
A new high-resolution biomarker record from Core PS93/025 provides new insights into the Arctic sea-ice evolution and for the first time documents the formation of the NEW Polynya on the eastern North Greenland continental shelf during the late Holocene

Summary

Introduction

Arctic sea ice is a key component in our climate system, regulating the global heat budget, influencing the atmospheric circulation (Serreze et al, 2016) and the global ocean circulation via the Atlantic Meridional Overturning Circulation (AMOC; Sevellec et al, 2017). The recent dramatic loss of Arctic sea ice (Fig. 1) can affect global climate beyond the polar regions, changing the planetary albedo, surface heat and freshwater flux (Thomas and Dieckmann, 2008; Sevellec et al, 2017). Due to a reduction in the iceocean albedo effect, declining Arctic sea ice is expected to amplify anthropogenic climate change in the polar regions (Manabe et al, 1992; Randall et al, 1998; Screen and Simmonds, 2010). Over the past three decades, summer sea-ice extent and thickness have declined by 50%, much faster than predicted by climate models (see review by Stroeve et al, 2012; Serreze et al, 2016; Walsh et al, 2017; Notz and Stroeve, 2018)

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Results

Discussion

Conclusion