The ice sheet in Greenland faces many changes and one of them is hiding in plain sight - the snowy layer covering most of its surface. Normally acting as a sponge for refreezing meltwater, this layer is important for the overall fate of the ice sheet, but it’s changing in ways researchers currently do not fully understand. Now, a 13 million Euro grant from the European Research Council (ERC) enables an international consortium including Horst Machguth, a researcher from Fribourg, to investigate this problem. 

The top layer of the Greenland ice sheet consists of firn, a type of compressed snow with countless air pockets. The firn layer can be up to 100 meters thick and normally acts as a huge sponge, soaking up most of the meltwater created on the ice sheet’s surface each summer. About 90% of the entire ice sheet is covered by this firn layer, but as Arctic temperatures rise, this ice-sheet blanket is changing fast. Now, more meltwater is percolating into Greenland’s firn than previously. 

A 13 million Euro research grant
„The Greenland ice sheet’s firn covered area is shrinking and becoming saturated with meltwater. We expect that the firn will lose a great deal of its current meltwater retention ability. We need to find out how the entire ice sheet will react to this,“ says Professor William Colgan from the Geological Survey of Denmark and Greenland (GEUS). He is part of a group of four researchers from four different European research institutions who just received a major grant of 13 million Euro from the European Research Council (ERC) Synergy Grant.

Filling in the gap
The changes happening in the Greenland ice sheet’s firn layer are currently not being monitored well enough, according to the team of researchers. Most previous firn studies have focused mostly on the highest elevations of the ice sheet, where there is little meltwater. Other studies have focused on the melt zone around the ice-sheet margin. Between these domains lies a vast area of quickly changing firn that researchers know little about.

“FirnMelt is the first large project that focuses on how this area is changing and, even more important, how its changes will affect the entire ice sheet,” says Professor Horst Machguth from the University of Fribourg in Switzerland. He explains that, since the increasing amount of meltwater from the inner part of the ice sheet could potentially reach the underlying glacier bed, it could alter the hydrological system of the entire ice sheet. This could change the velocity at which the ice moves. Since changes in ice flow velocity can impact the amount of ice that discharges into the oceans, in the end, this might be changing Greenland’s sea level contribution. And not in a positive direction.  

Observations and new projections
The extreme variability in the Greenland ice sheet hydrology has recently taken the researchers by surprise. New observations and models are required to get on top of projecting the shifting fate of Greenland’s firn and meltwater under climate change. The FirnMelt team plans extensive activities to achieve this goal like airborne and satellite observations or in-situ observations using novel traverse vehicles.

All of this will enable the team to produce the most comprehensive ice-sheet hydrology model of Greenland, following meltwater from the ice-sheet surface to its base, and how it will impact the entire ice sheet. 

About the FirnMelt Project
Beside the University of Fribourg, the FirnMelt Project partner institutions are the Geological Survey of Denmark and Greenland, the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany and the Utrecht University, The Netherlands. It is funded with 13 Mio. Euros by the European Research Council for a duration of 6 years, starting in March 2026. 

The project is one of 66 projects receiving funds from the ERC Synergy Grant and synergy is a key word in the project. With different expertise of the four project leaders Horst Machguth, William Colgan, Angelika Humbert and Michiel Van den Broeke, the team plans to tackle current challenges of ice sheet hydrology from firn, linking it to subglacial water discharge and its interaction with overall glacier dynamics.

Photo: Horst Machguth