Huge icebergs in Antarctica are actually relatively common. All ice shelves eventually collapse and form icebergs. When Antarctic glaciers (essentially massive, slow rivers of ice) reach the ocean, the ice floats, forming a shelf that remains attached to the glacier. Tidal and wave action flexes the shelf until it breaks - this can be accelerated by temperature increases. Just a few years ago, a chunk of the Larsen Ice Shelf almost as big as the Wilkins piece floated around for a few months until waves battered it against shore and broke it apart.

The total meltdown of the world's glaciers would raise sea level worldwide 200 meters. Even a small percentage of that would be bad news. And once they start melting, the loss of sun reflectivity would only serve to boost global warming.

So what's the good news? Icebergs are made of fresh water. Someone with the wherewithal could tow this iceberg to a hot region and use it as potable water. It's not exactly a new idea. In 1973, the RAND Corporation published a study called "Antarctic Icebergs as a Global Fresh Water Resource." They figured out that if someone could harvest just ten percent of Antarctica's total annual iceberg yield, it would provide water for 500 million people and make $10 billion each year (that's $48 billion today, if I did the inflation adjustment correctly). It would cost about $8 (again, in 1973 value) to deliver 1,000 cubic meters to Southern California. Factor in increased annual iceberg yield due to global warming and by 2018 the phrase "it's like a goldmine" could be replaced by "it's like an iceberg." Photo by National Snow and Ice Data Center (NSIDC).

Massive ice shelf on verge of breakup [cnn.com]