The European Space Agency’s Envisat imaging satellite has spotted the breakup of the enormous A53A iceberg, located just east of South Georgia Island in the southern Atlantic Ocean. A53A calved off Antarctica’s Larsen Ice Shelf in April 2005.
Envisat’s Advanced Synthetic Aperture Radar produced images showing a huge north-to-south fissure running through the berg on March 1. The data indicated that the berg was unstable and likely to break apart. ASAR is able to produce high-quality images of icebergs and ice sheets and is capable of differentiating between different types of ice, because it is able to see through clouds and local darkness — conditions often found in polar areas.
Just three days later, Envisat’s Medium Resolution Imaging Spectrometer captured the iceberg splitting into two bergs of 30 kilometers apiece in length. (By comparison, South Georgia Island is approximately 180 kilometers long.) From ESA, here’s a dramatic picture of the split.
Several different processes can cause an iceberg to form, or "calve," including deterioration from high temperatures or the sun's radiation, action from winds and waves, or a collision with another iceberg. A53A broke up in relatively warm waters, making it highly likely that numerous smaller icebergs will calve from the pair. Calving is one of the Antarctic’s most spectacular sights; here’s a rare sea-level video of another breakup as it happened.
But don’t be too enthralled. The increasing disintegration of Antarctic ice masses is another worrisome sign of global warming, and portends an eventual rise in global sea levels that could devastate heavily inhabited coastal areas.