Mysterious force moves the Ross Ice Shelf in Antarctica every day

Antarctica’s Ross Ice Shelf, a massive floating ice platform about the size of France, shifts suddenly a few inches at least once a day. Now, this isn’t some creeping glacier-like motion. A hidden force within Antarctica’s ice, far from the surface, triggers these sudden shifts.

Ross Ice Shelf

The Ross Ice Shelf is the largest ice shelf of Antarctica, an immense floating platform of ice that plays a crucial role in the continent’s glacial system and the global climate. Here’s a deeper look into its significance, characteristics, and the role it plays in our planet’s ecology:

Geographic and physical characteristics

• Size and location: The Ross Ice Shelf covers an area of around 487,000 square kilometers, roughly the size of France. It is situated in the Ross Sea, extending off the continent’s coast into the ocean.
  
• Thickness: Its thickness varies significantly, ranging from about 100 meters to several hundred meters. The thickest parts are generally found where the shelf anchors against the continent.
  
• Formation: It is formed by the accumulation and compaction of snow, which over time turns into ice. Glaciers flowing into the sea from the Antarctic mainland feed it, continually adding mass.

Importance of the Ross Ice Shelf

• Climate regulation: Ice shelves play a significant role in regulating the planet’s climate. They do so by reflecting solar radiation back into the atmosphere and by acting as a barrier that controls the flow of glaciers into the ocean.
  
• Sea level regulation: By holding back the flow of ice from land into the sea, ice shelves like the Ross help to moderate sea level rise. If ice shelves collapse, the rate at which glaciers move into the ocean increases, contributing to higher sea levels.
  
• Ocean circulation: The cold, fresh water from melting ice shelves impacts ocean circulation patterns, which in turn affect global climate systems including weather patterns.

The Ice Shelf and the ice stream

This phenomenon centers around the Ross Ice Shelf and a conveyor belt of ice that feeds into it – an ice stream. Ice shelves are thick masses of ice floating on the ocean, extending out from glaciers flowing inland.

Ice streams are sections within these glaciers that flow at a faster rate. This particular ice stream, known as the Whillans Ice Stream, is one of several feeding the huge Ross Ice Shelf.

“We found that the whole shelf suddenly moves about 6 to 8 centimeters (or 3 inches) once or twice a day, triggered by a slip on an ice stream that flows into the ice shelf,” explains Doug Wiens, a professor of earth, environmental, and planetary sciences at Washington University in St. Louis.

Why is the discovery important?

Ice shelves are similar to massive brakes. They slow down the glaciers emptying into the sea, preventing too much ice from melting and raising sea levels. A collapsing ice shelf means runaway glaciers, potentially causing problems for coastal communities worldwide.

The movement of the Ross Ice Shelf could be an early indicator of changes impacting the stability of the ice shelf itself.

Movement of Ross Ice Shelf

Scientists describe this movement as a sudden surge caused by uneven behavior within the ice stream. Imagine a large section, over 60 miles wide, remaining stationary while other sections of the ice stream inch forward.

Abruptly, this chunk breaks free and surges onward up to 16 inches within a few minutes. This happens once or twice every day, jolting the entire Ross Ice Shelf as it does.

The mystery of ice stream movement

Scientists have been studying ice streams for decades, trying to understand why their speeds change. While probably not directly linked to human-caused warming, this sudden surging might be due to variations in water present at the base of the glacier, impacting how easily it slides.

“I’ve published several papers about the Whillans Ice Stream slip events in the past, but had not discovered that the whole Ross Ice Shelf also moves until now,” says Wiens.

Study significance

These slip events create stresses within the ice shelf, potentially leading to fractures or icequakes. Currently, this is considered a normal part of life for this ice shelf.

“There is a worry that the Ross Ice Shelf will someday disintegrate since other smaller and thinner ice shelves have done so,” Wiens emphasizes. We know the Ross Ice Shelf broke apart around 120,000 years ago, causing runaway ice loss.

This new finding is one more piece in our understanding of this complex, changing Antarctic landscape. It underscores the interconnectedness within the ice world and the forces at play there – some visible, some taking place deep below the frozen surface.

The study is published in Geophysical Research Letters.

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