Environmental ancient DNA as a proxy for sea ice reconstructions

Sea ice cover is a 'canary in the coal mine' for the Arctic and global climate state. Sea ice extent is rapidly decreasing and Arctic summers are predicted to be sea-ice free by 2050. Because sea ice is crucial for sustaining local Arctic communities, international ecosystem services and biological diversity, there is an urgent need to understand variability in sea ice cover over longer time scales. Our best tool to predict future sea ice coverage is to understand past trends. Research activities investigating past natural variability in sea ice extent rely on microfossils and/or organic biomarkers produced by organisms that are associated with sea ice. Both methods have inherent assumptions and limitations, which make sea ice reconstructions non-trivial. To improve our understanding of sea ice history in the recent geological past, with special attention to rapid climate change events (e.g. Dansgaard/Oeschger cycles, Heinrich events), we propose to develop a new proxy for determining past sea ice cover using environmental ancient DNA (aDNA) from Arctic sediments. We have obtained preliminary results indicating that aDNA can be a valuable proxy to reconstruct past sea ice cover. Here we propose to further develop and assess the aDNA proxy and compare with traditional microfossil and organic biomarker proxies in order to provide a reference framework for understanding present-day and future accelerated sea iceloss as a consequence of anthropogenic climate change. More reliable proxies will aid policy makers and end-users of ecosystem services to make well-informed decisions on climate change mitigation in the Arctic.