A giant iceberg has broken off Antarctica, but not because of climate change

A giant iceberg has broken off Antarctica, but not because of climate change

Before and after the breakup of the iceberg on the Brunt Ice Shelf.

Science | glaciology

It has been identified as A-81 and does not pose a threat, at least imminently.

An iceberg of 1,550 square kilometers -approximately the size of the city of London- and a thickness of 150 meters, broke off the Brunt ice shelf, in Antarctica, on January 22, as reported by the British Antarctic Survey ( BAS). Despite the spectacularity of the event, scientists had known for years that this would happen and do not directly relate it to climate change.

A decade ago, researchers at the BAS Halley Research Station, from where glaciologists monitor the behavior of the Brunt Ice Shelf, discovered significant cracks in this icy surface, and two major breaks have occurred in the past two years. In fact, in 2017, the BAS Halley moved to a safer place in the event of a possible ice break. After the split on Sunday, experts say that both the station and the 21 people who currently work there are safe.

The new iceberg is called A-81 and Andrew Shepherd, director of the NERC Center for Polar Observation and Modeling, and principal scientific advisor of the CryoSat satellite mission of the European Space Agency (ESA), clarifies the main doubts regarding its breakup and future trajectory.

- What caused the detachment?

- It's part of the natural cycle. Glaciers move into the ocean, and eventually icebergs break off when the floating section becomes too brittle.

- Although it has not had a big impact on this iceberg, how is climate change affecting the ice of Antarctica?

- Climate change causes glaciers to flow faster, which speeds up the rate at which icebergs calve. Also, it can cause more storms and faster melting, increasing the chance of them breaking.

- What will happen now with all this ice?

- The ice was already afloat, so it does not pose a threat to sea level rise. Now this iceberg will begin its journey around the Weddell Sea, as it is moved by the ocean current.

- Is he a threat?

- It currently poses no risk but will eventually end up crossing Drake Passage where it can be a hazard to ships. Even so, until that happens it can take more than a year.

- What consequences does the detachment of icebergs have at a geological level?

Icebergs carry rocks from Antarctica and spread them across the seafloor as they melt. We have learned a lot about past climate changes by studying them, as it helps us figure out how big the ice sheet was once.

Other previous landslides

The new A-81 iceberg is about 1,550 square kilometers, that is, five times the size of Malta. By comparison, the A-68 iceberg, which broke off the Larsen-C Ice Shelf in July 2017, was 5,800 km2. For its part, the A-74 had 1,270 km2 when it detached from the Brunt ice shelf in February 2021; while the A-76 had 4,320 km2 when it detached, in May 2021, from the Ronne ice shelf.

The denomination of the icebergs is made up from the Antarctic quadrant (division of Antarctica into four parts taking as reference the meridians of 0°, 180°, 90° East and 90° West) in which they are originally sighted, to which is added a sequential number. Thus, quadrant A is 0-90W; the B, 90W-180; the C, 180-90E; and the D, 90E-0.

If the iceberg subsequently breaks up, each fraction adds a sequential letter to its name. For example, the new iceberg is called A-81 and has a northern split identified as A-81A.