Environment: Quantifying glacier ice loss via frontal ablation

A total of around 52 gigatonnes of ice was lost via frontal ablation from approximately 1,500 glaciers in the Northern Hemisphere (excluding the Greenland ice sheet) from 2010–2020, estimates a paper published in Nature Communications. The findings suggest that this process can have a stronger control on mass loss from glaciers than melt in some regions, and has implications for assessing sea-level rise and for the identification of hotspot areas where this process takes place.

Glaciers lose mass via different processes. Frontal ablation, which includes iceberg calving, refers to the mechanism by which ice is lost by glaciers to the ocean and is independent of surface melt. However, previous research has only computed some types of frontal ablation in the Northern Hemisphere.

To assess the role of frontal ablation from 2000–2020, William Kochtitzky and colleagues identified approximately 1,500 marine-terminating glaciers in the Northern Hemisphere, separate to the Greenland ice sheet. They combined measurements or estimates of ice thickness, surface velocity and changes in its end position and found that frontal ablation can be the largest contributor to mass loss in some regions. The authors suggest that ice discharge from 2000 to 2020 was the equivalent of around 2.10 mm sea-level rise, and from 2010–2020 frontal ablation contributed approximately 52 gigatonnes of ice to oceans. They also assessed which areas are affected by this process, identifying potential hotspots and marine ecosystem impacts, and indicate that among the most affected coastal areas are the Russian Arctic, Svalbard and Alaska.