A huge iceberg that was once three-and-a-half times the size of London is melting, releasing 152 billion tonnes of fresh water into the ocean, a study has found.
According to researchers, the 'megaberg' has melted the equivalent of 61 million Olympic-sized swimming pools, or enough to fill Loch Ness 20 times, with a potentially devastating effect on marine habitats.
Experts used satellite images to track the iceberg, which has been dubbed A68A, after it snapped off from the Larsen-C Ice Shelf in Antarctica in July 2017.
When it first broke off from the ice shelf, it was the largest iceberg on Earth and the sixth-largest on record.
It stayed the same size for around two years but started to melt as it drifted and entered seas around the sub-Antarctic island of South Georgia.
At its peak the huge iceberg, which measured 5,719sq km - or quarter the size of Wales - was melting at a rate of seven metres per month.
Such a colossal release of water is likely to damage the island's fragile habitat, experts have warned.
Laura Gerrish, mapping specialist at British Antarctic Survey, said: "A68A was an absolutely fascinating iceberg to track all the way from its creation to its end.
"Frequent measurements allowed us to follow every move and break-up of the berg as it moved slowly northwards through iceberg alley and into the Scotia Sea where it then gained speed and approached the island of South Georgia very closely."
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Anne Braakmann-Folgmann, PhD candidate at the University of Leeds, said: "This is a huge amount of melt water, and the next thing we want to learn is whether it had a positive or negative impact on the ecosystem around South Georgia.
"Because A68A took a common route across the Drake Passage, we hope to learn more about icebergs taking a similar trajectory, and how they influence the polar oceans."
Tommaso Parrinello, CryoSat Mission Manager at the European Space Agency, said: "Our ability to study every move of the iceberg in such detail is thanks to advances in satellite techniques and the use of a variety of measurements.
"Imaging satellites record the location and shape of the iceberg and data from altimetry missions add a third dimension as they measure the height of surfaces underneath the satellites and can therefore observe how an iceberg melts."
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