Catastrophic disappearance of Antarctic ice due to chain reaction

Nature : A 12 000-year-old ice shelf in Antarctica suddenly disintegrated in 2002. Last week at the International Glaciological Society meeting in Beijing, Douglas MacAyeal of the University of Chicago and colleagues presented their findings regarding that catastrophic loss. Using a mathematical model, the researchers found that decades of warming temperatures were melting the ice and forming lakes on Antarctica’s Larsen B Ice Shelf. By 2002, there may have been as many as 3000 lakes, each about 1000 meters across. Because of ice’s elasticity, it can bend under pressure from a lake of water sitting on top of it. If the water drains from the lake, however, the ice will bounce back and cause fracturing in the surrounding ice. Gecause the Larsen B Ice Shelf had so many lakes so tightly packed together, drainage from one of the lakes would affect all the others, which may have set off a chain reaction of fracturing. That effect would explain the observation of sudden calving off of thin icebergs from the shelf. It was “like the smashing of glasses at the throw of a stone,” said MacAyeal.