GRAIL

GReenland ice sheet to Atlantic tipping points from Ice-sheet Loss

Start date
1 April, 2025
End date
31 March, 2030

GRAIL aims to quantify the key link between the North Atlantic ocean and the Greenland Ice Sheet: melting and calving at Greenland’s glaciers. The physical processes controlling melting and calving are chronically under-studied due to the difficulty in accessing ice-choked fjords. We will monitor these processes using new ocean/ice/airborne platforms in both East and North-West Greenland, and then build these new observations into physical models of melting and calving.  The new process understanding will be built into the UK Earth System Model, and feed into a prototype Early Warning System.

Supported by the ARIA Forecasting Tipping Points progamme, GRAIL brings together a wide range of expertise from a large international team:

  • British Antarctic Survey
  • Cambridge University
  • Cornell University
  • Danish Meteorological Institute
  • Edinburgh University
  • Leeds University
  • National Oceanography Centre
  • Oregon State University
  • Reading University
  • Scottish Association for Marine Science
  • St. Andrews University
  • Stirling University
  • Technical University of Denmark
  • The Alan Turing Institute

All BAS staff involved in the project are listed in the ‘People’ tab above.

Summary

The stability of the Atlantic Ocean circulation under increasing greenhouse gases is of critical concern due to its potential to create large, abrupt changes in European and global climate. Central to this discussion is the question of whether open-ocean convection in the North Atlantic Subpolar Gyre can be sustained under a future freshening of the sea surface. Future changes in freshwater forcing of the North Atlantic could come from rivers, sea ice, precipitation, or ice loss from the Greenland Ice Sheet. The Greenland freshwater source is growing, highly uncertain, and holds the potential for abrupt future change.

Greenland ice loss is occurring through increased surface melting and glacier discharge. Surface melting processes are relatively well understood, and are incorporated into climate models. Changes in ice discharge, on the other hand, are far less well constrained. They are triggered at the glacier terminus through changes in melting and iceberg calving in the >200 deep, narrow fjords surrounding Greenland. Melting is controlled by changes in fjord ocean conditions and by the injection of subglacial meltwater from beneath the glaciers. Calving and fjord conditions are modulated by melting, the presence of iceberg mélange, and fjord geometry. However, the physics of fjord melting and calving are completely absent from climate models.

Project Aims

GRAIL will advance our understanding of melting and calving processes by launching new ocean/ice/airborne platforms and advancing robotic exploration, physical modelling and Artificial Intelligence approaches. We will build melting and calving physics into the UK Earth System Model to enable prediction of the global impacts of Greenland ice loss, and we will deliver a prototype Early Warning System (EWS) built on physical parameterisations and statistical emulators. Our project aims are illustrated below.

 

Map
GRAIL will make new observations at Petermann and Kangerlussuaq glaciers, which drain the North-West and Eastern Greenland Ice Sheet. They are prime examples of the two different settings for ice/ocean interactions in Greenland – a floating ice shelf or a vertical melting glacier face.  The central panel also shows the interaction between Greenland outlet glaciers and the main ocean currents in the North Atlantic.  These two glaciers were identified as prime targets in a community paper on Greenland fjord/glacier observation, which this image is taken from (Straneo et al., 2019).

 

Diagram
Melting and calving of Greenland glaciers involves a set of inter-related physical processes that are currently poorly sampled due to the difficulty in accessing the ice-choked fjords and heavily-damaged glacier surface. In GRAIL we will develop and deploy a range of new sensors and observing platforms to overcome these accessibility issues.  We will conduct a major research cruise to Kangerlussuaq Fjord in East Greenland, and use hot-water drilling to access the ocean beneath the floating tongue of Petermann Gletsjer in North-West Greenland.

 

Diagram, shape
Our new GRAIL observations will be used to constrain new physical process models of each component of the melting and calving processes.  These models and the observations will them be used to train process parameterisations and AI emulators.  All of these components will then be used to build fjord processes into the UK Earth System Model and a prototype Early Warning System.