Huge iceberg menaces Antarctica

Collision with ice tongue imminent

The monster iceberg responsible for breaking off a sizeable chunk of the Drygalski ice tongue in Antarctica is on the rampage again. This time, the Long-Island-sized chunk of ice is heading towards the ice tongue of the Aviator Glacier, where the latest images (snapped on 18 May) reveal it is heading rapidly for a collision.

The marauding iceberg heads towards the Aviator Glacier

The picture was snapped on 18 May with the Envisat satellite's Advanced Synthetic Aperture Radar (ASAR). The ASAR in Wide Swath Mode (WSM) captures a spatial resolution of 150 metres across a 400-km swath.

The Aviator Glacier was discovered in 1955, and was named for the airmen who did so much to open the continent up to explorers and scientists. The Aviator is a major valley glacier which descends from the plateau of Victoria Land along the west side of the Mountaineer Range. It meets the ocean at Lady Newnes Bay, where it forms a floating ice tongue that extends into the water for about 25 kilometres.

The iceberg, designated B15-A, is the largest remaining piece of an even bigger berg that calved from the Ross ice shelf in 2000. The original iceberg, dubbed B15, was roughly the size of the island of Jamaica. Since the B15-A broke away from its mother-berg, it has drifted into McMurdo sound. Here, it has been nothing but trouble to the locals.

Its huge presence blocked ocean currents, leading to a build up of sea ice that decimated local penguin colonies as the birds could not access the open ocean to feed.

During the last Antarctic spring, the glacier drifted slowly towards the Drygalski ice tongue, and looked set to strike a devastating blow to the glacial run-off. Eventually the berg struck the glacier with only a glancing blow, nevertheless breaking off enough of the ice tongue that maps of the region needed redrawing.

Now it is menacing another stretch of coast, one unusually rich in wildlife. Researchers fear that if the berg stays put for any length of time, it could again lead to a dangerous build-up of sea ice, blocking access to the sea for the local Adelie penguins, Skuas and Weddell seals.

If you have the bandwidth, you can check out high-res versions of the picture above, and animations of the Drygalski collision here. ®

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