Antarctic Sea Ice Proxies from Marine and Ice Core Archives Suitable for Reconstructing Sea Ice over the Past 2000 Years

Elizabeth R Thomas,Mirko Severi,Claire S Allen,Juliane Mueller,Xavier Crosta,Victoria L Peck,Amy C F King,Johan Etourneau,V Holly L Winton

doi:10.3390/geosciences9120506

Abstract

Dramatic changes in sea ice have been observed in both poles in recent decades. However, the observational period for sea ice is short, and the climate models tasked with predicting future change in sea ice struggle to capture the current Antarctic trends. Paleoclimate archives, from marine sedimentary records and coastal Antarctic ice cores, provide a means of understanding sea ice variability and its drivers over decadal to centennial timescales. In this study, we collate published records of Antarctic sea ice over the past 2000 years (2 ka). We evaluate the current proxies and explore the potential of combining marine and ice core records to produce multi-archive reconstructions. Despite identifying 92 sea ice reconstructions, the spatial and temporal resolution is only sufficient to reconstruct circum-Antarctic sea ice during the 20th century, not the full 2 ka. Our synthesis reveals a 90 year trend of increasing sea ice in the Ross Sea and declining sea ice in the Bellingshausen, comparable with observed trends since 1979. Reconstructions in the Weddell Sea, the Western Pacific and the Indian Ocean reveal small negative trends in sea ice during the 20th century (1900–1990), in contrast to the observed sea ice expansion in these regions since 1979.

Highlights

Sea ice plays a major role in modulating regional and global climate
Climate model simulations of future warming are heavily dependent on the historical sea ice area data [16], and it is of global importance that we provide reliable paleo-sea ice reconstructions to ensure that the climate models tasked with predicting future changes are fully optimised
Through various chemical and biological processes, the amounts of sea ice each year affects the concentrations of a number of aerosols in the atmosphere and subsequently deposited into the snow layers

Summary

Introduction

Sea ice plays a major role in modulating regional and global climate. It governs the amount of heat and sunlight absorbed by the earth’s albedo effect and the ocean-atmosphere transfer of gas and energy.Sea ice influences biogeochemical cycling, water mass formation, ocean circulation, precipitation and atmospheric circulation [1,2]. Sea ice plays a major role in modulating regional and global climate. It governs the amount of heat and sunlight absorbed by the earth’s albedo effect and the ocean-atmosphere transfer of gas and energy. Sea ice influences biogeochemical cycling, water mass formation, ocean circulation, precipitation and atmospheric circulation [1,2]. It is a potential major source of dimethylsulphide (DMS) [3] (a climate-cooling gas), and is thought to modulate the physical and biological processes that can draw down atmospheric CO2 into the ocean [4]. The total Antarctic sea ice cover has been steadily increasing since systematic

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Conclusion