Who counts the world's icebergs?

Who counts the world's icebergs?

Who counts the world's icebergs?

Answers to your questions about the news.
April 20 2005 7:12 PM

Who Counts the World's Icebergs?

And why don't they count the "bergy bits"?

That's one ...
There's one ...

An enormous iceberg known as "B-15A" has collided with the 43-mile-long Drygalski ice tongue in Antarctica, according to satellite photos taken this past weekend. The collision formed a new iceberg by knocking a 3-mile chunk off of the icy protuberance, but this one won't get its own name, and its movements won't be officially tracked. Who monitors icebergs, and who names them?

Daniel Engber Daniel Engber

Daniel Engber is a columnist for Slate

For icebergs in the Southern Hemisphere, it's the National Ice Center, a collaborative office run by the U.S. Navy, the U.S. Coast Guard, and the National Oceanic and Atmospheric Administration. (In the Northern Hemisphere, the International Ice Patrol keeps track of the ice.) In 1976, the center (then known as the Joint Ice Center) began to follow the formation and movements of large icebergs using satellite imagery. Today it provides the most comprehensive data on Antarctic iceberg movements in the world. Most international agencies defer to its nomenclature for icebergs in Antarctica, though some—like the European Space Agency—gather their own satellite tracking data.

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The center only names and tracks the largest, densest, and most hazardous icebergs within a set distance from the South Pole. To get a name (like B-15A), an iceberg must be at least 10 nautical (or 11.5 regular) miles long—which is why the 3-mile chunk that just broke off the Drygalski ice tongue will remain anonymous.

Very large blocks of floating ice like B-15A are named according to where and when they first broke off (or "calved") from an ice shelf or glacier. The first letter represents one of the four longitudinal quadrants of Antarctica—on one side, quadrant A faces the southern tip of South America, while on the other, quadrant C faces Australia. Iceberg B-15A broke off from the quadrant that faces out toward the eastern part of the Ross Sea.

The National Ice Center also assigns each major iceberg a number, corresponding to how many named icebergs have emerged from a particular quadrant since 1976. The first iceberg that appeared in the B quadrant, for example, was named B-1. Large icebergs tend to break apart, though, and any pieces that are still over 10 nautical miles in length will be given new names, with letter postscripts. So B-15A is the first large piece of ice that broke off from the 15th iceberg to form in quadrant B.

Smaller chunks of ice without proper names do get classified into categories. To be an iceberg proper, a block must be about 30 meters long and cover an area of at least 500 square meters. Smaller chunks are called "bergy bits" and cover between 100 and 300 square meters. "Growlers" are smaller still, covering about 20 square meters, or an area of about 15 feet by 15 feet.

More permanent features, like the Drygalski ice tongue, are often named after notable polar explorers. Erich von Drygalski traveled to Antarctica in the first years of the 20th century and became the first balloonist there in 1902.

Explainer thanks Matthew Lazzara of the University of Wisconsin at Madison and Sean Helfrich of the National Ice Center.