DICING WITH DISASTER
Earlier this month, a colossal iceberg dislodged from Antarctica. At about twice the size of Rakiura/Stewart Island, the long and narrow slab known as A-76 is the largest iceberg in the world. The spectacular satellite footage was global news.
A-76 broke off the Ronne Ice Shelf, the continent’s second-largest floating ice platform, which stretches across a massive bay in the Weddell Sea to the east of the Antarctic peninsula. When scientists at the US National Ice Center made the official announcement, they were quick to point out that iceberg calving is a natural process and the forces that cleaved the berg from the face of the ice shelf could not be directly attributed to climate change.
In any case, even if the 181km-long and 26km-wide berg now drifts north into warmer waters and eventually melts completely, it won’t make any difference to global sea levels – just as a melting ice cube doesn’t change the water level in a glass.
But the news sharpened attention on Antarctica’s accelerating melting and the question of how much its icy cap will add to future sea levels. An even more urgent question is whether we’re approaching a temperature threshold that would trigger irreversible disintegration of some Antarctic glaciers and commit us to multi-generational sea-level rise over coming decades and centuries. “There’s a concern that as we approach 1.5°C or 2°C global warming, that may
