Greenland Lakes Make Ice Flow 40% Faster Towards Sea

Greenland's glaciers are now flowing up to 40% faster into new lakes, a significant increase compared to glaciers on land.
By Newsroom | Environment, Science |

NEW RESEARCH INDICATES FRESHWATER BODIES NEAR THE GREENLAND ICE SHEET ARE SIGNIFICANTLY INCREASING THE SPEED AT WHICH GLACIERS MOVE TOWARDS THE SEA. THIS PHENOMENON, FUELLED BY A WARMING CLIMATE, MAY CONTRIBUTE MORE SUBSTANTIALLY TO RISING GLOBAL SEA LEVELS THAN PREVIOUSLY UNDERSTOOD.

The formation of freshwater lakes at the periphery of Greenland's vast ice sheet is demonstrably speeding up the flow of major glaciers. Researchers have analyzed satellite data, creating maps of these "ice-marginal lakes" and observing the resulting changes in ice surface velocity. The findings, published in Communications Earth & Environment, show that glaciers terminating in these lakes exhibit markedly higher speeds.

GLACIERS UNDER PRESSURE

These lakes, termed ice-marginal lakes or IMLs, emerge in depressions exposed as glaciers retreat. Much like glaciers that calve icebergs into the ocean, those encountering these lakes can experience a buoyant effect. The water in these lakes partially lifts the glacier's leading edge, potentially increasing melting from beneath the ice. This process, combined with other dynamics, leads to accelerated glacier movement and, consequently, greater ice mass loss.

Studies examined 102 glaciers across Greenland, comparing those that flowed into lakes with those terminating on land. The results indicate that glaciers flowing into larger lakes can move up to 40 percent faster than those entering smaller bodies of water. This suggests a direct correlation between lake size and the degree of acceleration.

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A GROWING CONCERN

As global temperatures continue to climb, the extent of these meltwater lakes is expected to expand. This growth is anticipated to amplify the trend of glacier acceleration, leading to a potentially steeper increase in the rate of global sea-level rise. The research offers a critical perspective on the complex feedback loops at play within Greenland's rapidly changing glacial environment.

BACKGROUND

THE GREENLAND ICE SHEET

The Greenland Ice Sheet is the second-largest ice body in the world, holding enough frozen water to raise global sea levels by approximately 7.4 meters (24 feet) if it were to melt entirely. Its surface area is roughly 1.71 million square kilometers (660,000 square miles), about 80% of Greenland's total land area.

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GLACIAL DYNAMICS

Glaciers are rivers of ice that flow downhill under their own weight. Their speed is influenced by various factors, including the steepness of the underlying bedrock, the temperature of the ice, and the presence of meltwater at the base or terminus. Meltwater can lubricate the glacier's base, allowing it to slide more easily over the ground. When glaciers meet a body of water, such as a lake or the ocean, they can experience calving, where ice breaks off to form icebergs. The interaction with water can also affect the glacier's stability and flow rate.

Frequently Asked Questions

Q: Why are freshwater lakes in Greenland making glaciers move faster?
New research shows that freshwater lakes forming as glaciers melt are lifting the ice edge. This makes the glaciers slide into the sea up to 40% faster, especially if the lakes are large.
Q: How much faster are Greenland's glaciers moving because of these lakes?
Glaciers that flow into larger freshwater lakes can move up to 40 percent faster than those flowing into smaller lakes or onto land. This is a significant increase in speed.
Q: What does this mean for sea levels around the world?
Faster moving glaciers mean more ice is lost from Greenland and enters the ocean. This could cause global sea levels to rise more quickly than scientists previously thought.
Q: How did scientists find out about these fast-moving glaciers?
Researchers used satellite data to map freshwater lakes near the Greenland ice sheet. They then measured how fast 102 different glaciers were moving into these lakes compared to others.
Q: Will these lakes get bigger in the future?
Yes, scientists expect these meltwater lakes to grow larger as the Earth gets warmer. This means the problem of faster glacier movement and ice loss is likely to become worse.