Iceberg A68a, once the world’s largest iceberg, is now gone, broken up into chunks too small to track. While the iceberg is recent history, scientists are still studying its impact.

In 2017, a massive iceberg broke off from Antarctica’s Larsen C ice-shelf. The iceberg, which would be designated as A68a, weighed roughly one trillion tons and measured 4,200 sq km, or almost the size of the state of Delaware.

At first, A68a stayed more or less stationary, temporarily aground close to the ice-shelf. In July of 2020, it broke free and started to drift. There was a real concern that A68a could be on a collision course with the British Overseas Territory of South Georgia. The massive berg was roughly the same length as South Georgia island itself. There was a strong possibility that the berg could ground and anchor itself offshore of the wildlife haven. If that had happened, it would have posed a grave threat to local penguins and seals.

Fortunately, iceberg A68a began to melt and break up before it grounded on South Georgia. At the height of its melting, the BBC reports that the monster iceberg was dumping about150 times the amount of water used daily by all UK citizens.

Now scientists are studying the impact of that much fresh water being released into the Southern Ocean. The New York Times reports that scientists, led by Anne Braakmann-Folgmann, a doctoral student at the Center for Polar Observation and Modeling at the University of Leeds in Britain, used satellite imagery to monitor the shape and location of the iceberg over the course of its journey.

The researchers, whose findings were published in the journal Remote Sensing of Environment, estimated that melting in the vicinity of South Georgia resulted in the release of about 150 billion tons of fresh water.

A large influx of fresh water on the surface could affect the growth of phytoplankton, at the lower end of the food chain, or it could alter the mix of phytoplankton species available.

Not only is the water fresh, not salty, but it also contains a large amount of iron and other nutrients. Ms. Braakmann-Folgmann is helping another group of researchers, from the British Antarctic Survey, who are trying to determine the ecological effects of the iceberg and the meltwater.

Thanks to David Rye for contributing to this post.