Birth of an iceberg( This animation comprised of images a...)

This animation, comprised of images acquired by Envisats Advanced Synthetic Aperture Radar (ASAR) instrument, shows the breaking away of a giant iceberg from the Pine Island Glacier in West Antarctica. Spanning 34 km in length by 20 km in width, the new iceberg covers an area nearly half the size of Greater London.

The animation highlights the movement in the area between September 2006 and October 2007. The Pine Island Glacier is visible stretching from the right of the image to the centre. The tongue of Pine Island is shown moving inland between September 2006 and March 2007. Between April and May 2007, the detached iceberg in front of Pine Island moves significantly. Also in May 2007, a crack in Pine Island becomes visible. By October, the new iceberg has completely broken away.

Several different processes can cause an iceberg to form, or calve, such as action from winds and waves, the ice shelf grows too large to support part of itself or a collision with an older iceberg. Since Pine Island Glacier was already floating before it calved, it will not cause any rise in the world sea level.

Iceberg calving like this occurs in Antarctica each year and is part of the natural lifecycle of the ice sheet. A 34-year long study of the glacier has shown that a large iceberg breaks off roughly every 5-10 years. The last event was in 2001.

Pine Island the largest glacier in the West Antarctic Ice Sheet (WAIS) is of great interest to scientists because it transports ice from the deep interior of the WAIS to the ocean and its flow rate has accelerated over the past 15 years.

The Pine Island Glacier is up to 2500 m thick with a bedrock over 1500 m below sea level and comprises 10 percent of the WAIS. According to a study by scientists at the British Antarctic Survey (BAS) and University College London (UCL) using ESA's ERS satellite data, a loss of 31-cubic km of ice from the WAISs interior from 1992 to 2001 was pinpointed to
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