New research from the Geological Survey of Denmark and Greenland and University of Copenhagen shows that meltwater in tunnels beneath Greenland’s ice sheet causes it to change speed, and in some places, accelerate greatly towards the ocean. This can cause an increase in melting, especially in a warming climate.
Using extensive satellite measurements, the researchers have conducted a study that shows how movements of the ice sheet appear to be closely linked with meltwater flow beneath the ice.
Using artificial intelligence, the researchers analyzed ice movements that they can now divide into four categories based on patterns of movement. This information has been missing from the understanding of why the velocity of ice at the same site can change over time.
As meltwater from the surface reaches the bottom of the ice, it flows mainly towards the edge of the ice sheet through melted channels. The researchers found that the design of these channels, also known as subglacial pathways, affects the movement of the ice above.
If the channels, which act as a type of drainage system, are poor at diverting water away, the pressure at the bottom rises and reduces friction between ice and bottom. As a result, the ice moves faster towards the ocean. However, if the drainage system is effective, the ice moves more slowly.
“This results in four variations in the velocity of ice that we’ve discovered at various locations across the ice sheet. For example, the velocity can slow in the middle of the melting season, when meltwater is plentiful, because the drainage system suddenly becomes efficient. Or the system remains inefficient and under high pressure. So, the velocity accords with the amount of meltwater,” explains the Senior Researcher.
https://phys.org/news/2023-02-knowledge-ice-sheet-movement-sea.html