New research findings show that the bed beneath the Greenland Ice Sheet is structured differently than long assumed. Instead of predominantly solid rock, scientists have discovered extensive layers of sediment beneath the ice. This discovery has far-reaching implications for our understanding of climate change and future sea-level rise.
The Greenland Ice Sheet is considered a so-called tipping element in Earth’s climate system. This means that beyond a certain point, an accelerated and nearly unstoppable melting process begins. With a thickness of up to 3,300 meters, the ice stores enormous amounts of water. If it were to melt completely, global sea levels would rise by about seven meters, with dramatic consequences for coastal regions worldwide.
Until now, researchers assumed that the ice mainly rests on solid rock. However, a research team from the United States has now demonstrated that in some areas, sediment layers up to 200 meters thick lie beneath the ice. These are much softer than rock and allow the ice to glide more easily. As a result, the ice sheet can move more quickly toward the ocean, accelerating melting.
In addition to this discovery, scientists are observing another phenomenon: Greenland is rising. As the ice melts, the land beneath it is relieved of weight and slowly lifts – a process known as isostatic rebound. Measurements show that Greenland has risen by about 23 centimeters over the past ten years alone. In the future, this could even lead to the formation of new islands.
However, this process also affects other regions. While Greenland is rising, other areas are sinking slightly, including parts of Germany’s North Sea coast. For example, the measured sea level in Cuxhaven has risen by 43 centimeters since 1843, though this increase is not solely due to ocean warming.
These new insights highlight how complex the interactions within the climate system are. The discovery of sediment layers beneath Greenland’s ice could help improve future predictions and also underscores how urgent action against climate change remains.
Heiner Kubny, PolarJournal