A trillion-tonne iceberg, one of the largest ever recorded, has snapped off the West Antarctic ice shelf, scientists who have monitored the growing crack for years said.

The largest volcano range on earth has been discovered, two kilometres below the surface of Antarctica.

A paper published by a research team from Edinburgh University reveals scientists have found 91 volcanoes under the ice sheets in the west of Antarctica - in addition to the 47 already known in the region.

The largest stands at almost 4000 metres - taller than New Zealand's highest peak, Aoraki Mount Cook, which stands at 3724 metres.

Andreas Kalvig Anderson The largest volcano range on earth has been discovered, under Antarctica. (File photo)

The discovery adds to the growing concern for a region already affected by climate change, and scientists say if one were to erupt it could further destabilise the ice sheets.

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Glacier expert Robert Bingham, and one of the authors of the paper, told the The Guardian experts need to determine how active the volcanoes were as quickly as possible.

"Anything that causes the melting of ice – which an eruption certainly would – is likely to speed up the flow of ice into the sea.

"We had not expected to find anything like that number. We have almost trebled the number of volcanoes known to exist in west Antarctica."

Most volcanism in the world is present in regions that have only recently lost glacial covering after the last ice age, he said.

Bingham said this could happen in west Antarctica where climate change has caused significant warming which has affected the ice sheets.

"If they are reduced significantly, this could release pressure on the volcanoes that lie below and lead to eruptions that could further destabilise the ice sheets and enhance sea level rises that are already affecting our oceans."

All the volcanoes discovered are covered in ice, which is up to four kilometres thick in some areas, and ice-penetrating radar was used to analyse measurements underneath the surface.

The measurements were compared with previous surveys to look for evidence of volcanic cones protruding into the ice.

"We also suspect there are even more on the bed of the sea that lies under the Ross ice shelf, so that I think it is very likely this region will turn out to be the densest region of volcanoes in the world," Bingham said.

"Greater even than east Africa, where mounts Nyiragongo, Kilimanjaro, Longonot and all the other active volcanoes are concentrated."