World’s biggest iceberg is almost as tall as The Shard and weighs one trillion tons

The world's largest iceberg clocks in at nearly one trillion tons and is almost as tall as the UK's biggest skyscraper, The Shard.

It's almost impossible to put into perspective, but we'll try: it's equivalent to three times the size of New York City and more than twice the size of Greater London.

It's got the rather dry name of A23a, and ever since it broke away from the Antarctic coast in 1986, it has remained anchored on the ocean floor.

But in recent months, scientists noticed that this mega iceberg was on the move, after it began drifting northwards at a rate of around 30 miles per day.

Satellite images have measured the giant block of ice - all thanks to European Space Agency's CryoSat-2 mission - revealing it has a depth of 920 feet (280 meters).

FYI, that's almost as tall as the UK's tallest skyscraper, The Shard, which comes in at 1,016 feet (310 meters).

At this stage it remains unclear what direction the giant iceberg will take, but scientists are closely monitoring the situation.

They believe ocean currents and strong winds could soon force it through a zone dubbed "iceberg alley", a common route for icebergs to float toward the sub-Antarctic island of South Georgia.

If the iceberg, which weighs just shy of a trillion tons, grinds to a halt offshore, the island's abundant wildlife may be at risk.

After splitting from the Filchner Ice Shelf in 1986 it swiftly parked up in what is known as the Weddell Sea.

Here it remained an ice island for nearly four decades before suddenly starting to drift.

A group of scientists on board the RRS Sir David Attenborough came face to face with the iceberg last week and captured it on film.

Andrew Meijers, chief scientist aboard the research ship, said: “It is incredibly lucky that the iceberg’s route out of the Weddell Sea sat directly across our planned path, and that we had the right team aboard to take advantage of this opportunity.

“We’re fortunate that navigating A23a hasn’t had an impact on the tight timings for our science mission, and it is amazing to see this huge berg in person — it stretches as far as the eye can see.”