AN ICEBERG weighing more than a trillion tonnes has been spotted breaking away from an Antarctic ice shelf.

Nasa’s Aqua Modis satellite instrument allowed scientists from the Swansea University-led Midas project to detect the huge split from the Larsen C ice shelf between Monday and yesterday.

Other spacecraft, such as Europe’s Sentinel-1 satellite-radar system, confirmed the rift by measuring the juxtaposition in temperatures between ice and water.

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Covering an area of approximately 6000 square kilometres, the 200m-thick tabular iceberg – expected to be named A68 – is not in danger of moving anywhere fast. Experts warn, however, that currents and weather patterns could shift the mass gradually northward, where it would be a potential hazard for shipping.

For those struggling to come to terms with the vastness of the iceberg, the space covered by it is equivalent to more than a quarter of the land mass of Wales – or 857 football pitches.

The largest ever recorded by satellite, in 2000, measured 11,000 square kilometres, while in 1956 a US Navy icebreaker claims to have come across an iceberg of around 32,000 square metres.

Nevertheless, the calving has reduced the mass of the Larsen C ice shelf by approximately 12 per cent and will permanently alter the landscape of the Antarctic Peninsula, according to scientists.

Researchers have been tracking a giant crack in the ice for over a decade. They admit, however, that predicting the destiny of one of the largest icebergs on record will be difficult.

Professor Adrian Luckman of Swansea University (pictured right), lead investigator of the Midas project, said: “We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few kilometres of ice.

“It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.”

Scientists have classed the rift as a “natural event” and say that since the ice was floating before it calved away it will have no immediate effect on sea level.

However, they have acknowledged that it puts the ice shelf in a vulnerable position. There are concerns that Larsen C could follow the example of its neighbouring ice shelf Larsen B, which disintegrated in 2002 after a similar event.

If further significant rifts were to occur in the area, glaciers which flow off the land behind could suddenly speed up their approach to the ocean, which could impact on sea levels, experts say.

Prof Luckman added: “In the ensuing months and years, the ice shelf could either gradually regrow, or may suffer further calving events which may eventually lead to collapse – opinions in the scientific community are divided.

“Our models say it will be less stable, but any future collapse remains years or decades away.”

Rod Downie, head of polar programmes at WWF, said: “The sheer scale of this natural calving event is impressive – we will need to redraw the map of the Antarctic Peninsula.

“And whilst this is Antarctica doing what Antarctica does, it demonstrates just how fragile the polar regions are.

“The polar regions drive our oceans and atmosphere. But west Antarctica has experienced some of the most rapid rates of warming on the planet in recent decades, and that’s not good news for iconic species such as Adelie or emperor penguins.

“This demonstrates why we need to urgently and globally tackle climate change head on, starting in the UK with the UK Government outlining how we plan to meet our international commitments to reduce carbon emissions.”

Paul Johnston, head of Greenpeace International’s science unit (pictured left) described it as “possibly yet another signal of the global impact of climate change”.

He said: “No-one knows for sure if climate change played a definitive role in the break of the Larsen C ice shelf, but given the relatively recent break-up of other shelves, and the contribution thought to have been made to erosion of the ice by warmer waters around the Antarctic Peninsula in those cases, it seems likely that human activities are a factor.

“We’re still in the safe zone for avoiding catastrophic climate change. But we must act fast. Decisions taken now by governments and industry will decide whether billions of people have safe, prosperous lives in the future.”