ice sheet

It's the first hard evidence that the ice sheet formerly covering Britain and Ireland produced such large bergs.

The researchers found deep, comb-like grooves, interpreted to have been created by the keels of large icebergs that broke off the British-Irish ice sheet more than 18,000 years ago.

No ice shelf setting is the same, but the researchers say their findings from the former British-Irish ice sheet could help understand how Antarctica might respond to today's rapidly warming climate.

"But the argument that the collapse of ice shelves triggered ice sheet collapse is only part of the story; the main forcing is warmer air temperature and warmer ocean temperature," he argued.

Hundreds of ice shelves surround about three-quarters of today's Antarctic ice sheet, helping to hold back its vast glaciers.