The looming threat from Antarctica

From The Economist

The arctic and Antarctic are, fittingly, polar opposites. The first is an ocean surrounded by continents, the second a continent surrounded by an ocean. In the one, communities of indigenous people and settlers; in the other, only transients, there for a season or two. Nuclear-armed powers have faced off across the Arctic since the cold war; the same conflict saw a governance regime of peaceful scientific collaboration created for Antarctica that is more utopian in its conception than any other agreement in the annals of diplomacy. The north has the majesty of polar bears, the south the pathos of penguins. The two are united in facing profound upheaval because of global warming. But compared with the changes affecting the Arctic, those threatening the Antarctic are greatly underappreciated.

In part that lack of attention is because of Antarctica’s remoteness; the biggest base there, America’s McMurdo, is almost 4,000km from the nearest city (Christchurch, in New Zealand). Visits are for the most part made only by scientists, adventurers and support staff. In part, too, there is seeming stasis. Change in Antarctica is not like that in Alaska, where melting permafrost buckles roads and topples buildings; or in Siberia, where the smoke from burning tundra paints the skies and sears the lungs. Indeed, for a long time scientists tended to see Antarctica as relatively stable, at least over the short to medium term. Yes, its ice sheets contain enough water to raise the seas by 60 metres—but any collapse would take centuries.

That turns out to have been complacent. Earth’s largest refrigerator is, as we describe in this week’s Science and technology section, showing alarming signs of a big thaw, one which will have consequences for the rest of the planet. Extreme events like the disappearance of an area of sea ice the size of Greenland during last year’s austral winter are a symptom of a quickening underlying instability. Glaciologists are talking of a “regime shift”. Parts of one of the enormous ice sheets that cover 98% of the continent are sliding towards the seas.