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Icebergs in the Southern Ocean
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Ute Kaden/PolarTREC

Icebergs

Icebergs are large pieces of ice floating in the ocean that have broken off of ice shelves or glaciers in Earth's polar regions. They are a part of the cryosphere.

Approximately 90% of an iceberg's mass is below the surface of the seawater. Because ice is less dense than water, a small portion of the iceberg stays above the seawater.

Icebergs can be huge. The largest ones are known as ice islands. The widest iceberg on record was 80 kilometers across. The tallest known iceberg had 168 meters of ice sticking out above the water. Since the part above the water is only 10% of its total size, imagine how much ice a large iceberg has underwater!

In 1912, a brand new ship called the RMS Titanic, collided with an iceberg in the North Atlantic and sunk on its first voyage.& Only about a quarter of the passengers and crew who were on board the Titanic survived. After this huge disaster, the International Ice Patrol was formed to track icebergs in the North Atlantic, ensuring that other ships did not meet a similar fate. The Patrol first monitored icebergs from ships. Later, in the 1930s, airplanes were used to keep track of icebergs. Today, icebergs can be tracked using satellites. In an average year, nearly 500 icebergs pass through the shipping routes in the North Atlantic Ocean. The Patrol warns sailors when the danger of icebergs is high.

As they travel from the polar areas where they form into warmer waters, the ice melts, and icebergs become smaller.

Last modified April 18, 2007 by Lisa Gardiner.

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