Plume-like structures extending from the base of the ice-sheet up to a kilometre and a few tens of kilometres in length have been observed in the interior of the Antarctic and Greenlandic Ice Sheet. A team of scientists from the University of Zurich, CH, and the British Antarctic Survey, UK, reproduced these features with computer simulations of freezing on water running beneath the ice sheet. They demonstrate that the plume shape and size depends upon the interplay between the ice flux and the basal freeze-on rate, where a small ice flux and a low freeze-on rate results in tall plumes.
Implications for ice-core studies
Ice sheets – also known as continental glaciers with an ice mass larger than 50'000 square kilometre – grow primarily by accumulation of snowfall that becomes ice over time. This study now highlights that especially in areas with a rugged bedrock surface, water freezing on to the base of the ice sheet can cause it to grow.
This new insight is crucial for the correct interpretation of ice-cores as a climate archive: Old ice is pushed upward from the base and is therefore protected from melting at the ice-sheet base. This leads to a jump in age at the plume margin, where old ice is folded around the ice-body and can mix-up the climate record near the ice-sheet base.
Basal freeze-on generates complex ice-sheet stratigraphy’ von Gwendolyn Leysinger Vieli, Carlos Martín, Richard C.A. Hindmarsh & Martin Lüthi wurde in Nature Communications publiziert. DOI: 10.1038/s41467-018-07083-3
Dr. Gwendolyn Leysinger Vieli
University of Zurich
Department of Geography
Telephone +41 44 635 52 19, +41 76 713 30 08