A “mega” iceberg releases 152 billion tons of fresh water into the ocean

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When massive iceberg A68A broke away from its pack ice in July 2017, it was the sixth largest iceberg on record. Today, more than half has disappeared.

A study published on January 10 in the journal Environmental remote sensing shows that the huge chunk of ice broke off from the Larsen Ice Shelf in Antarctica in 2017 and traveled northeast to South Georgia in 2021. The iceberg once measured about 5,719 square kilometers, nearly half the size of Connecticut, but it began to disintegrate once it arrived. to the island of South Georgia in the Atlantic Ocean.

The European Space Agency described it as a “mega” iceberg, claiming that it remained relatively the same size for the first two years of its life, as it remained in the cold waters of the Weddell Sea near the Antarctic Peninsula. Then it began its “epic” journey through the Drake Passage, the ESA said, and everything changed.

By January 2021, it had lost about 3,200 square kilometers, more than half of its area. Now it’s a little bigger than Rhode Island.

Researchers from the University of Leeds, the Center for Polar Observation and Modeling and the British Antarctic Survey studied the iceberg using satellite images and found that during these years of travel, the he iceberg was getting smaller as it separated and gradually melted. During its three-and-a-half-year journey, the iceberg is estimated to have lost about 544 cubic kilometers of ice, about a third of which was due to basal melting.

During the time it was around South Georgia, researchers found the iceberg released about 152 billion tons of fresh water and nutrients into the ocean over the course of about three months. This amount of water could fill approximately 61 million Olympic swimming pools.

This significant loss could have “a potential impact on the island’s rich ecosystem”, the study says.

One of the observers’ concerns was that the iceberg would collide with the seabed near the island. Researchers found, however, that the iceberg came closest to the island about 38.5 miles offshore in December 2020. Although the A68A did not run aground on the seabed, according to researchers, it is likely that it hit the ground in some of the shallower areas. as it rotated, and is thought to have affected “only a small area”.

It is, however, possible that other icebergs could end up stranded in the area in the future, which could potentially destroy organisms residing on the seabed. A stranded iceberg can also disrupt ocean currents and prevent island penguins from feeding in the sea, researchers said.

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Trajectory of the A68A and historical icebergs overlaid on a bathymetric map.

Observe the disintegration of the A68A iceberg from space


The study’s lead author, Anne Braakmann-Folgmann, said in a declaration that the iceberg released a “tremendous amount of meltwater”. She told CBS News that it’s too early to tell what the specific impact of the A68A will be, but that in general, cold freshwater from icebergs changes the physical properties of seawater that affect it. surrounds and releases nutrients that can “promote organic production”.

South Georgia and the South Sandwich Islands are a “wildlife refuge”, according to their government, home to around 5 million seals and 30 different species of birds, a third of which are considered threatened or near threatened.

The waters surrounding the islands are also a critical area for the migration of populations of whales, fish and Antarctic krill, which, according to the government, are a “key link” in the food chain of the Southern Ocean.

“In this case, penguins, seals and whales that feed in the waters around South Georgia could benefit from greater food availability,” Braakmann-Folgmann said. “And especially penguins and seals, which raise their offspring on the island, depend on nearby food sources.”

The researchers added, however, that melting could potentially alter the properties of the ocean in ways that would also impact currents, which could, in a ‘worst-case scenario’, divert krill, a crucial source of food for the whales, far from the island. Studies on the subject are still ongoing.



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