Relative Sea-Level Changes and Ice Sheet History in Finderup Land, North Greenland

Andreas Nilsson,Marit-Solveig Seidenkrantz,Astrid Strunk,Laura B Levy,Torben L Lauridsen,Nicolaj K Larsen,Jesper Olsen

doi:10.3389/feart.2018.00129

Abstract

Rising global sea level caused by melting ice sheets poses a major challenge in a persistently warming climate. The Greenland Ice Sheet (GrIS) is among the main contributors, and in order to make accurate predictions of future ice retreat and sea level rise, it is imperative to understand how the ice sheet responded to global warming in the past. Reconstructions of relative sea level (RSL) are a key constraint in models of past ice sheet fluctuations, however, high-precision data has until now been sparse in North Greenland. In this study, we present a RSL reconstruction for Finderup Land, North Greenland based on five isolation lakes located between 19.6 and 81.2 m a.s.l. The transition between marine and lacustrine sediments has been identified using XRF, lithological interpretation, and foraminiferal analysis. Age constraints are based on 14C dating of foraminifera and paleomagnetic age correlation. Our results show that Finderup Land was ice free by 10.8 ± 0.2 cal ka BP with a subsequent rapid RSL fall occurring from 9.5 ± 0.2 to 8.0 cal ka BP, at which point the RSL started to approach present level. Furthermore, we establish the marine limit to be minimum at 81.2 m a.s.l. We compare our data to modeled RSL predictions for the area and our results indicate a faster RSL fall, which in turn reflects that the ice retreat was more rapid than estimated and possibly, that the ice sheet in North and Northeast Greenland was larger than previous estimates suggest. (Less)

Highlights

The Greenland Ice Sheet (GrIS) is a major contributor to global sea level rise, its response to future climate changes remains relatively unconstrained (Church et al, 2013; Gregory et al, 2013)
Holocene Ice Retreat, North Greenland predictions, glacial isostatic adjustment (GIA) models rely heavily on constraints from field evidence, the timing of ice retreat and the magnitude of isostatic response, which is conveyed through reconstructions of relative sea level (RSL) (Bennike et al, 2002; Sparrenbom et al, 2006a,b; Long et al, 2008, 2011; Woodroffe et al, 2014; Whitehouse, 2018)
Our data show a rapid RSL fall from 9.5 ± 0.2 cal ka BP to 8.0 ka, at which point the RSL began to approach present sea level

Summary

Introduction

The Greenland Ice Sheet (GrIS) is a major contributor to global sea level rise, its response to future climate changes remains relatively unconstrained (Church et al, 2013; Gregory et al, 2013). Holocene Ice Retreat, North Greenland predictions, GIA models rely heavily on constraints from field evidence, the timing of ice retreat and the magnitude of isostatic response, which is conveyed through reconstructions of relative sea level (RSL) (Bennike et al, 2002; Sparrenbom et al, 2006a,b; Long et al, 2008, 2011; Woodroffe et al, 2014; Whitehouse, 2018). Few bivalves have narrowly restricted depth habitats, which give an uncertainty on the paleo-shoreline elevation of several meters (Pilarczyk and Barber, 2015) Both shells and driftwood can be reworked and displaced from the shoreline during storm events (Funder et al, 2011a,b). We use the new isolation lake data to infer the glaciation history in North Greenland

Methods

Results

Discussion

Conclusion