Exploring the use of organic biotic remains for reconstructing Antarctic cryosphere variability: Sea ice dwellers as storytellers

Abstract

According to the latest report of the Intergovernmental Panel of Climate Change, Earth’s temperature will rise at least 1.5°C on average globally, and even 2-3 times more on the poles. Therefore, studying the geological past is important to determine the implications for the stability of the Antarctic ice sheet and sea ice. As we cannot travel back in time, this research uses the so-called sedimentary archive, existing of layers of ocean floor, from which remains of organisms, ocean currents and climate conditions can be derived. In this thesis research methods based on organic fossils and molecules obtained from layers of ocean floor are explored and improved upon and subsequently applied to reconstruct the history of the ocean close to the Antarctic ice sheet. This thesis describes the diversity of organic microfossils obtained from a core with sediments up to 11.000 years old, which serves as reference material for further study. To improve our understanding of the environmental conditions that these microfossils preferred, their abundance is compared to data on meltwater discharge, surface water temperature and sea-ice concentrations. Application of these methods on a core containing the previous interglacial, shows that during periods of warming processes were at play that resemble the processes we see around Antarctica today, such as an increase in meltwater discharge. A reconstruction of the period between 34 and 26 million years ago, when CO2 concentrations were comparable to today, show that seawater temperatures were on average 17°C and there was only little sea ice present.