Icebergs are thick masses of ice floating in the ocean. They form when large chunks of ice break off a glacier or an ice shelf and float free in the sea. This is called calving. Many new icebergs were formed in 2002, with the break up of the Larsen B ice shelf.

Icebergs can vary in size, but the largest-known iceberg, B15A, was 296 km long and 38 km wide when it broke off the Ross ice shelf in 2001. This is about the same size as Jamaica –10,600 km².

This sounds huge – but you wouldn’t have been able to see the whole thing as around 90% of an iceberg is actually under water.

The reason why ice floats and is lighter than water is that a certain mass of ice occupies more space than the same mass of water. This is related to the characteristics of hydrogen bonds.

In 2006, icebergs were sighted off New Zealand’s Otago coastline – the first time they’d been seen so far north in many years. Where did they come from? What is an iceberg, anyway? Look at the NIWA website here for more informatin on icebergs..

Did you also know that all icebergs over 1900 m along at least one axis are monitored by the US National Ice Center and given names to assist with tracking.

Useful link

The varied sights and sounds of Antarctic icebergs begin to reveal themselves in this Radio NZ podcast with NIWA scientist and Deep South National Science Challenge director, Dr Mike Williams: Voice of the iceberg 2.

 

    Published 19 July 2007