Our international team aims to answer how sea ice and Antarctic ice shelves interact and vary through time. Ice shelves are a crucial tipping element of the West Antarctic Ice Sheet, and sea ice protects the ice shelves from disintegration. Currently we know very little about sea ice, ice shelves and their interaction on short and longer time scales. This can be attributed to the lack of suitable sediment records and the limited availability of tools (or proxies) for sea ice and ice shelf reconstructions.
We now have collected a unique set of sea floor samples and started sampling a 9 m long sediment core from the Weddell Sea. The sediment core contains ca. 130,000 year record of the Antarctic climate, sea ice and ice shelves. Samples have been collected for a first, low-resolution study of the diatoms, biomarkers, palynology and paleogenomics. After several laboratory tests, we are in the process of choosing the optimal method for ancient DNA extraction. This happens in close collaboration with the international partners in Australia, Germany and the UK. Sampling for the entire project will be completed by the end of 2022, after which we will be able to produce the first multi-proxy data that can determine the role of sea ice in Antarctic ice shelf (in)stability and Southern Ocean circulation over the past 130,000 years, including the Last interglacial, a periods of Earth’s history where global climate was warmer than today.
In this project, we gather a cross-disciplinary, international team to provide for the first time essential knowledge on Antarctic sea ice–ice shelf variability and interaction on (sub)millenial time scales. Sea ice plays a key role in the global climate system and in the Southern Ocean it protects ice shelves from disintegration, a crucial tipping element of the West Antarctic Ice Sheet. Despite the pivotal role in the climate system, there is limited knowledge on sea ice–ice shelf interaction in the geological past. This knowledge gap exists due to the limited availability of (sea ice) proxy methods and the lack of suitable sediment records for reconstructing sea ice–ice shelf interactions.
Using a unique set of sediment samples, we will evaluate existing geochemical and paleontological methods as well as a novel sedimentary ancient DNA approach for reconstructing sea ice–ice shelf variability and interactions. Subsequently, we will apply our new methodology to a Weddell Sea sediment core to generate the first (sub)millennial biomarker and sedimentary ancient DNA record back to >130,000 years ago. We will focus on the Last Interglacial, where we will compare our proxy records and climate model experiments to obtain a dynamical insight into sea ice–ice shelf variability during a critical time in Earth’s history where global climate was warmer than today. As such, the project is highly relevant for understanding the natural variability of Antarctic sea ice–ice shelves, their impact on ocean circulation and the Antarctic Ice Sheet, and ultimately on global sea level. Within the project, we commit to train a young researcher in the emerging field of paleogenomics and aim to establish Norway at the forefront of paleogenomics in the marine environment.
