A four-year record of basal melt rates at the Ekström Ice Shelf in Antarctica shows that enhanced melting of the ice shelf occurs in winter and spring, while rates are decreased in summer and autumn. 

The authors of the new study hypothesise that the dense water formed during sea-ice formation erodes the water column stratification during late winter and spring, leading to an increase in the buoyancy of the ice shelf water plume. 

An idealised plume model supports this hypothesis, indicating that the plume velocity is the primary driver of seasonal basal melt rate variability, while changes in ambient water temperature play a secondary role in the range of oceanographic conditions that are observed below the Ekström Ice Shelf. 

Figure: Time series of 7 d average basal melt rate from autumn 2020 to spring 2023 (blue line) with sub-weekly variability represented by the standard deviation (shaded area). Credit Zeising et al. (2025), The Cryosphere.

The authors explain that:

“These findings offer new insights into the dynamics of ice–ocean interactions in East Antarctica, emphasising the need for further observations to refine our understanding of ocean variability within ice shelf cavities and improve assessments of ice shelf mass balance.”

Study co-author Tore Hattermann from the iC3 Polar Research Hub says:

“It is striking to see that the ice shelf melts most when the surface is coldest. That shows just how important the ice-ocean interactions are for Antarctic ice.”

“These findings remind us that Antarctic ice shelves respond to subtle changes in ocean circulation. To predict future sea-level rise, we need to understand not just how warm the ocean gets, but also how its density and flow patterns evolve.”

Find out more

The study “Enhanced basal melting in winter and spring: seasonal ice–ocean interactions at the Ekström Ice Shelf, East Antarctica” was published open access in The Cryosphere.

The lead author, Ole Zeising, works with the Alfred-Wegener-Institut in Bremen, Germany. iC3 Polar Research Hub’s Tore Hattermann contributed to the study.

Tore is a researcher at the Norwegian Polar Institute and at the Department of Geosciences at UiT The Arctic University of Norway. His research focuses on ocean-ice interactions in polar regions. He is particularly interested in how physical processes in the ocean affect ice shelf stability and sea-level rise.