Greenland Ice Sheet

The Greenland Ice Sheet is the second largest body of ice on Earth, surpassed only by the Antarctic Ice Sheet. Covering roughly 1.7 million square kilometres, it blankets about 80 per cent of Greenland’s surface. This massive glacial structure contains enough frozen water to raise global sea levels by more than seven metres if it were to melt entirely. The Greenland Ice Sheet plays a crucial role in regulating the global climate, influencing ocean currents, sea levels, and atmospheric conditions across the Northern Hemisphere.

Geological Formation and Structure

The origins of the Greenland Ice Sheet date back to the late Pliocene Epoch, around 2.6 million years ago, when a prolonged cooling phase led to the accumulation of snow and ice. Subsequent glacial and interglacial cycles during the Pleistocene Epoch shaped its present form. The ice sheet consists of layers of compacted snow transformed into glacial ice through compression over millennia.
Its thickness varies considerably, reaching depths of over 3,000 metres in central Greenland. The sheet features two main ice domes—one in the north and one in the south—connected by a saddle-shaped central region. Numerous outlet glaciers flow outward from these domes toward the sea, with some extending into the North Atlantic Ocean, forming floating ice tongues and generating icebergs through the process of calving.

Climatic and Environmental Significance

The Greenland Ice Sheet exerts a significant influence on global climate systems. It reflects a substantial portion of incoming solar radiation due to its high albedo, helping to moderate global temperatures. As a major freshwater reservoir, it also affects ocean salinity and circulation patterns, particularly the Atlantic Meridional Overturning Circulation (AMOC), which drives heat transport between the equator and the poles.
When ice melts from the surface or calves into the ocean, the resulting freshwater influx can disrupt these circulation systems, potentially leading to regional cooling in the North Atlantic and altered weather patterns across Europe and North America. Moreover, the loss of surface reflectivity caused by melting enhances further warming in a feedback loop known as the ice–albedo feedback.

Patterns of Melting and Ice Loss

In recent decades, scientific observations have recorded a significant acceleration in the rate of ice loss from Greenland. Satellite data from missions such as GRACE (Gravity Recovery and Climate Experiment) and ICESat indicate that the ice sheet is currently losing approximately 250–300 billion tonnes of ice per year. This process contributes to about one millimetre per year of global sea-level rise.
Melting occurs through several mechanisms:

• Surface melting, driven by rising air temperatures, particularly in the summer months.
• Basal melting, caused by geothermal heat and friction beneath the ice.
• Calving of outlet glaciers, especially along the west and southeast coasts.

Notable glaciers such as Jakobshavn Isbræ, Kangerlussuaq, and Helheim Glacier have shown marked retreat in recent years. Episodic events, including extreme heatwaves and atmospheric rivers, further exacerbate melting episodes, occasionally resulting in widespread surface melt events across the entire ice sheet.

Research, Monitoring, and Modelling

Scientific understanding of the Greenland Ice Sheet has advanced considerably through satellite remote sensing, field observations, and computer modelling. The European Space Agency’s CryoSat-2 and NASA’s Operation IceBridge provide critical data on ice thickness and surface elevation changes. Researchers utilise ice cores extracted from deep within the sheet to reconstruct past climates, revealing patterns of temperature variation, atmospheric composition, and volcanic activity over hundreds of thousands of years.
Climate models project that if current warming trends continue, the Greenland Ice Sheet could contribute between 0.3 and 1 metre to sea-level rise by 2100. These projections depend on global greenhouse gas emissions scenarios and the sensitivity of ice dynamics to temperature change.

Ecological and Global Implications

The melting of the Greenland Ice Sheet carries profound implications for global ecosystems and human societies. Rising sea levels threaten low-lying coastal regions, including major cities such as New York, London, and Dhaka, potentially displacing millions of people. Increased freshwater discharge alters marine ecosystems, affecting nutrient distribution, ocean stratification, and fish populations.
Within Greenland, melting also exposes previously ice-covered landscapes, leading to the formation of proglacial lakes and the emergence of new habitats. However, it also accelerates permafrost thaw, releasing methane and carbon dioxide—potent greenhouse gases that amplify global warming.

International Studies and Climate Policy

The Greenland Ice Sheet features prominently in international climate assessments conducted by bodies such as the Intergovernmental Panel on Climate Change (IPCC). It serves as a key indicator of anthropogenic climate change and a central element in discussions of global mitigation strategies. Efforts to limit global temperature rise to below 1.5°C, as outlined in the Paris Agreement, are aimed in part at slowing the irreversible melting of major ice sheets.
Collaborative research initiatives involving institutions from Denmark, the United States, Canada, and the European Union continue to monitor changes in the ice sheet using advanced observation networks. These efforts seek to refine predictions of future ice loss and to inform adaptation measures in vulnerable coastal zones worldwide.