Periodically, once or twice a decade, the river of krill seems to go astray. The year 2004 was a poor krill year at South Georgia, and 2009 has been a very bad one. A trend often masquerades as a cycle at the start, and evidence suggests that these scarce krill years may foreshadow a new South Georgia. A 2004 paper by Angus Atkinson of the British Antarctic Survey presented evidence of a 30-year decline in krill over a wide sector that holds more than half the krill stocks in the Southern Ocean.
Krill, especially the larvae, are dependent in winter on sea ice, and for the past few decades this layer of frozen seawater has been shrinking in some parts of the Antarctic (although overall it has increased slightly). Earlier this year a team of oceanographers reported that the seas to the west of the Antarctic Peninsula have been warming many times faster than the world average over the past 50 years. The warming is strongest near the surface and in winter—not good news for winter sea ice.
Neither is the news good for Antarctica's ice shelves—glaciers that extend into the ocean. Much of the vast Larsen Ice Shelf collapsed in 2002, and the smaller Wordie Ice Shelf vanished last April. If the magnifying glass of global warming has a focal point, it would seem to be the seas of the western Antarctic Peninsula, headwaters for South Georgia's river of krill.
On the day I left the island, the ship overtook an iceberg at sunset. It was the most beautiful thing I had ever seen. The glistening white wall towered above us, sheer as El Capitan and lovely in the last light of day. Icebergs have long been icons of the great white continent—Antarctica in microcosm. At a time when sprawling shelves of ice are disintegrating, this berg seemed to signify more. It was a last paradox. In this new era of climate change, icebergs are doubly symbolic, both of the pristine beauty of the Antarctic region and of the trouble that lies ahead.