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What is the life cycle of an iceberg?

The life cycle of a typical iceberg found in the North Atlantic today might look something like this:

Time LineIceberg development
1,000 B.C.Snow/Firn
950 B.C.Ice/Glacier
Glacier movement
1993 A.D.Calving
1996 A.D.Iceberg melt

Snow falls on the ice cap of Greenland. Then over the course of several months it changes into firn, which is basically a granular snow. Several decades later it is compressed into very dense ice by the weight of the firn and snow. Driven by the enormous weight of the ice cap above, the ice begins to flow seaward through openings in the fringe of the mountains (thinking of it like water leaking out of a cracked bowl may help). This force moves the rivers of ice known as glaciers up to sixty-five feet a day, eventually pushing the ice to Greenland's western coast.

At the glacier's terminus or end, huge slabs of ice are weakened and then broken by the action of the rising and falling tides. This process is called calving and results in an iceberg's birth. By the time these mountains of ice enter Baffin Bay they have seen nearly 3,000 years pass.

In order for an iceberg to reach the North Atlantic the currents typically take it from Baffin Bay through the Davis Strait and Labrador Sea. This is a long trip and most icebergs never make it. Most icebergs melt well before entering the Atlantic Ocean. One estimate is that of the 15,000 to 30,000 icebergs produced annually by the glaciers of Greenland only one percent (150 to 300) ever make it to the Atlantic Ocean. When an iceberg does happen to reach the Atlantic its long and traveled life quickly comes to an end melting rapidly in the warm waters.

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