Northeast Greenland Ice Stream

Northeast Greenland Ice Stream. It is the largest ice stream in the Northern Hemisphere, draining approximately 16% of the Greenland ice sheet into the Fram Strait and Greenland Sea. This immense feature, flowing through the Northeast Greenland National Park, is a critical component of the region's glaciology and a major focus of climate change research due to its significant potential contribution to global sea level rise. Its dynamics are influenced by complex interactions between the bedrock topography, subglacial hydrology, and warming ocean waters at its marine-terminating outlets.

Overview

The Northeast Greenland Ice Stream is a vast, fast-flowing corridor of ice embedded within the larger Greenland ice sheet. It was first identified and mapped in detail through satellite observations, notably by missions like NASA's Operation IceBridge and the European Space Agency's CryoSat-2. The stream's catchment area encompasses major tributaries such as the Nioghalvfjerdsbrae (79°N Glacier) and Zachariae Isstrøm, which terminate in floating ice tongues in the Nordenskjöld and Dijmphna Sound regions. Its behavior is monitored by international scientific consortia, including the Polar Portal and researchers from the Alfred Wegener Institute.

Physical characteristics

This ice stream is characterized by its immense scale, with a drainage basin covering an area comparable to the size of France. The underlying bedrock topography, mapped by surveys like NASA's IceBridge and BedMachine, reveals deep subglacial trenches and valleys that channel the flow. Ice thickness exceeds 3,000 meters in central areas, resting on a bed largely below sea level, which makes it potentially vulnerable to marine ice sheet instability. Key outlet glaciers, including Nioghalvfjerdsbrae and Zachariae Isstrøm, feature extensive ice shelves that have undergone significant disintegration in recent decades, influenced by warming in the North Atlantic.

Dynamics and flow behavior

The flow dynamics of the Northeast Greenland Ice Stream are governed by a combination of internal deformation and basal sliding. Motion is facilitated by the presence of pressurized subglacial water and deformable sedimentary beds, as revealed by seismic studies from institutions like the University of Texas at Austin. The acceleration and retreat of its major outlets are strongly coupled to oceanic forcing, with increased inflow of warm Atlantic Water from the East Greenland Current driving enhanced basal melt at the grounding lines. Events such as the breakup of the Zachariae Isstrøm ice shelf in the early 2000s, documented by Landsat program imagery, have led to sustained speed-up and inland thinning.

Contribution to sea level rise

The Northeast Greenland Ice Stream is recognized as a primary contributor to the mass loss from the Greenland ice sheet. Since the early 2000s, observations from GRACE and GRACE-FO satellites have recorded substantial ice discharge and thinning, particularly following the destabilization of its key outlet glaciers. Research published in journals like Nature Climate Change and Science indicates that this basin alone holds the potential to contribute over a meter to global sea level rise if fully destabilized. Its accelerated loss represents a significant component of the Intergovernmental Panel on Climate Change projections for future sea level scenarios.

Research and monitoring

Ongoing research on the Northeast Greenland Ice Stream employs a multi-disciplinary approach, combining satellite remote sensing, airborne geophysics, and in-situ measurements. Key monitoring programs include NASA's Operation IceBridge, the European Space Agency's CryoSat-2 and Sentinel-1 missions, and field campaigns led by the Alfred Wegener Institute and the Geological Survey of Denmark and Greenland. International collaborations, such as the Ice Sheet Mass Balance Inter-comparison Exercise, integrate data to improve models predicting its future behavior. Understanding this system is critical for initiatives like the World Climate Research Programme and assessments by the Intergovernmental Panel on Climate Change.

Category:Glaciers of Greenland Category:Greenland ice sheet