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Colossal iceberg breaks off Antarctica

Katharina Wecker
July 12, 2017

A chunk of ice the size of the US state of Delaware has broken off the Larsen C ice shelf, one of Antarctica's largest ice shelves. Scientists fear global warming is destabilizing Antarctic ice shelves.

An iceberg is pictured in the western Antarctic peninsula
Image: Getty Images/E.Abramovich

A 2,200-square-mile (5,800-square-kilometer) chunk of ice has separated from the Larsen C ice shelf. The new iceberg is one of the largest ever recorded.

Scientists who have been observing the growing crack in the Larsen C ice shelf for months announced Wednesday that the trillion-ton iceberg had finally broken away at some point in the last two days. 

Towards the end, the process accelerated. The crack suddenly extended 11 miles (17 kilometers) within one week in May.

The Larsen C ice shelf has now been reduced in sized by a record 10 percent.

While the new iceberg will have little to no immediate impact on the region or its biodiversity, scientists are worried about the long-term effects.

Infografik Karte Larsen C Ice Shelf – break-away of one of the largest icebergs ever recorded

Natural cycle

Breakaways of icebergs in the Antarctic are part of a natural cycle. Ice constantly flows toward the ocean. As a result, the ice shelf grows by an average of 760 yards (700 meters) each year.

At some point, a section breaks away and the ice shelf begins to grow again.

"The iceberg won't raise global sea levels," Daniela Jansen, a geophysicist at the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, told DW.

"It's like ice cubes in a glass of water. They don't raise the amount of water in the glass when they melt."

But the latest break could cause the Larsen C ice shelf to become unstable and eventually collapse.

Two smaller shelves to the north have already collapsed. Larsen A disappeared in 1995, and seven years later Larsen B collapsed.

Infografik Karte Larsen C Ice Shelf

Climate change culprit

Scientists attribute these collapses, and the retreat of several Antarctic ice shelves in recent decades, to global warming.

"The collapse of Larsen A and B has been connected to warming ocean temperatures in the Antarctic Peninsula," said Jansen. "The question is now whether the trend will spread toward the south and destabilize Larsen C, too."

Scientists will now be monitoring Larsen C to see if it follows the natural cycle and grows again - or melts further and eventually collapses.

Emperor penguin (Aptenodytes forsteri) adult with chick in Antarctica
Penguins don't live in the region of the break and will not be affectedImage: picture alliance/blickwinkel/R. Linke

Data from the Antarctic research project MIDAS at the University of Swansea in the United Kingdom already point toward an eventual collapse - which could take decades.

But unlike the icebergs that break off of the ice shelf, the ice behind it is on land. 

These shelves of sea ice act to hold back inland glaciers. If an ice shelf collapse allowed that ice to flow into the sea, it would melt, contributing to sea level rise.

Lessons for the future

The Antarctic is a highly complicated system, and scientists haven't been monitoring long enough to detect trends and make forecasts.

That's one reason the break of the Larsen C ice shelf has garnered so much attention.

"We receive new satellite images every six days. It's very exciting because we can monitor the entire process now - something we haven't been able to do before," Jansen said.

She added that lessons learned from Larsen C are potentially very significant for the future. "The data allows us to create models to make more long-term forecasts for even bigger ice shelves."

Scientists are worried the collapse of ice shelves, and the ice sheets behind them, could destabilize glaciers in Western Antarctica. The West Antarctic ice sheet holds enough frozen water to raise sea levels by about 6 meters (20 feet) if it were to melt.