World's largest iceberg breaks off from Antarctica ice shelf

Satellite images show slab that spans more than 4,000 square kilometres

The world's largest iceberg, more than four times the size of Abu Dhabi at 4,320 square kilometres, calved off an Antarctic ice shelf. European Space Agency

A giant slab of ice, more than four times the size of Abu Dhabi, has broken off from the frozen edge of Antarctica into the Weddell Sea, becoming the largest iceberg afloat in the world.

Its surface area spans 4,320 square kilometres. It measures 175 km in length and 25 km in breadth, the European Space Agency said on Wednesday.

By comparison, the capital of the United Arab Emirates has an area of 972 sq km. Spain's popular tourist island of Majorca in the Mediterranean occupies 3,640 sq km, while the US state of Rhode Island has a land mass of only 2,678 sq km.

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The newly calved berg, designated A-76 by scientists, was spotted in satellite images captured by the Copernicus Sentinel-1 mission, the space agency posted on its website with a photo of the enormous, oblong ice sheet.

The slab, which broke away from Antarctica's Ronne Ice Shelf, ranks as the largest existing iceberg on the planet. It surpasses the now second-placed A-23A, which is about 3,380 sq km in size and is also floating in the Weddell Sea.

Another massive Antarctic iceberg that had threatened a penguin-populated island off the southern tip of South America has since lost much of its mass and broken into pieces, scientists said earlier this year.

A-76 was first detected by the British Antarctic Survey and confirmed by the US National Ice Center based in Maryland using imagery from two polar-orbiting satellites.

Last year, currents took iceberg A-68A, the world’s largest at the time, from Antarctica to the coast of the South Georgia island.

Average sea levels have risen about 23cm since 1880, and about a quarter of that increase comes from ice melting in the Greenland and Antarctica ice sheets, along with land-based glaciers elsewhere, according to a study published in Nature earlier this month.

The study by 84 scientists from 15 countries concluded that the more ambitious national goals to cut greenhouse gas emissions and slow down climate change set recently are not enough to stop sea levels from rising. In fact, melting glaciers and ice sheets will raise sea levels twice as fast as they would if countries fulfilled their earlier pledges under the Paris Agreement.

The Ronne Ice Shelf on the flank of the Antarctic Peninsula is one of the largest of several enormous floating sheets of ice that connect to the continent's land mass and extend into the surrounding seas.

Periodic calving of large chunks of those shelves is part of a natural cycle. But some ice shelves along the Antarctic Peninsula have undergone rapid disintegration in recent years, a phenomenon scientists believe may be related to climate change, according to the US National Snow & Ice Data Centre.

The Ronne Ice Shelf is one of the largest bodies of floating ice, and ice calving is part of a natural cycle.

It is different from when ice breaks off from glaciers and melts into the ocean, causing sea levels to rise.

“Because ice shelves already float in the ocean, they do not contribute directly to sea level rise when they break up,” the National Snow and Ice Data Centre said.

“However, ice shelf collapse could contribute to sea level rise indirectly. Ice streams and glaciers constantly push on ice shelves, but the shelves eventually come up against coastal features such as islands and peninsulas, building pressure that slows their movement into the ocean.”