Unfolding reasons and consequences for the demise of the Greenland Ice Sheet: Perspective from biomarkers stored into basal ice

Ice cores retrieved over the past 50 years from the Greenland Ice Sheet archive invaluable clues about the response of large ice caps to global climate dynamics. Evidence indicates that during past warm interglacial periods, the Greenland Ice Sheet likely experienced significant retreat and may even have collapsed entirely. However, the factors controlling the stability of the Greenland Ice Sheet, its origin, and the environmental implications of its demise are still scarcely understood.

Basal ice, namely debris-rich ice found at the base of the ice mass near the substrate, has the highest potential to preserve information that may help constrain climate conditions conducive to the demise of an ice sheet. To contribute to unfolding these precious archives, we aim to develop and apply innovative organic geochemical techniques targeting fossil organic molecules that can be used as biological markers (in short, biomarkers) for the ecosystems that could have been entrained at the base of the Greenland Ice Sheet during its formation.

Here, we show preliminary results on the methodology developed, including tests on artificial and natural basal ice samples. We also performed geochemical analyses on material (river sediments and permafrost soils) collected from a modern periglacial environment during an expedition to the western margin of the Greenland Ice Sheet. The comparison with the organic geochemical fingerprint preserved in basal material retrieved in deep ice core drilling will help us to reconstruct past ecosystems and ultimately gain insights into the climate and environmental conditions that existed prior to the buildup of the Greenland Ice Sheet.