A few millimetres a year does not sound much but the loss of even a small part of Thwaites would not just help to speed this up further but would likely increase the severity of storm surges. Sea levels are rising fast: the annual rate of increase more than doubling from 1.4mm to 3.6mm between 20, and accelerating. Whether and how quickly they may collapse are some of the most important questions of the age. Should Thwaites fall apart, scientists believe the others would speed up, leading to the collapse of the whole ice sheet and catastrophic global sea level rises of several metres. Many are being held back because Thwaites acts like a cork, blocking their exit to the sea. Thwaites is worrisome, but there are many other great glaciers in Antarctica also retreating, thinning and melting as the Southern Ocean warms. Satellite studies show it is melting far faster than it did in the 1990s. It contributes about 4% of annual global sea level rise and has been called the most important glacier in the world, even the “doomsday” glacier. It is roughly 100 times larger, about the size of Britain, and contains enough water on its own to raise sea levels worldwide by more than half a metre. Thwaites makes Larsen B look like an icicle. Years of research by teams of British and American researchers showed that great cracks and fissures had opened up both on top of and underneath the Thwaites glacier, one of the biggest in the world, and it was feared that parts of it, too, may fracture and collapse possibly within five years or less.
This week, ice scientists meeting in New Orleans warned that something even more alarming was brewing on the West Antarctic ice sheet – a vast basin of ice on the Antarctic peninsula. It fell over like a wall and has broken as if into hundreds of thousands of bricks”, said one. Glaciologists were shocked as much by the speed as by the scale of the collapse.
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