If an iceberg breaks loose from Antarctica and nobody's there to hear it, does it make any sound? That koan is more than just a meditative exercise for Doug MacAyeal, a glaciologist at the University of Chicago who has spent decades pondering the vast Antarctic ice sheets and the huge bergs they spawn. Neither he nor anyone else has ever witnessed firsthand the calving of an Antarctic berg, and the process still mystifies polar experts.
That's because Antarctic icebergs are a world apart from their craggy Arctic kin. While the latter break off in spikes and spires from narrow glacial tongues, Antarctic bergs are flat slabs rent from shelves of fossil snow that stretch hundreds of miles over the coldest water on Earth. They can be thousands of times bigger than boreal bergs, closer to the size of a small state than a large ocean liner. The most enormous Antarctic bergs are rare and elusive, embarking only once every few decades in untraveled seas and rarely straying far from the frozen continent.
