Iceberg birth captured
Monday, 22 Oct 2007 14:48
The iceberg is seen just right off centre
Science In Focus
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Scientists have captured the birth of an iceberg nearly half the size of Greater London.
The process occurred in September 2006 and was completed by October 2007.
Its move away from the Pine Island glacier in west Antarctica was caught on camera by the Envisat satellite's advanced synthetic aperture radar (Asar) instrument.
Measuring 34km in length by 20km in width, the iceberg moved significantly between April and May 2007 before completely breaking away this month.
This process, known as calving, occurs in Antarctica each year and is part of ice-sheets' natural life cycles.
It is estimated that a large iceberg breaks off about every five to ten years; the last event was six years ago.
Calving is the result of a number of causes, including the impact of wind and wave action; the ice shelf becoming too large to support itself; and collision with an older iceberg.
Scientists are studying the Pine Island glacier - the largest glacier in the west Antarctic ice-sheet (WAIS) - as it transports ice from deep inside the WAIS to the ocean and its flow rate has increased in the past 15 years.
Although long-term regional changes worry scientists, the recent iceberg calving is said to not represent a significant change in the WAIS.