Economist story mentions U study on Greenland aquifer

Citing a study reported in the Journal of Glaciology this week, The Economist refers to Dr. Richard Forster's discovery of the huge Greenland aquifer which contains some 140 billion tonnes of liquide water.  If that were released in one go, it would incres Greenland's contribution to rising sea levels that year for 0.4mm to 0.6mm.  This would not matter as a one-off, but if it happened repeatedly as new firn formed the consequences could be serious.

FIRN is the name given by glaciologists to the partly compacted snow which lies, sometimes hundreds of metres thick, on top of glaciers, ice shelves and ice sheets. It looks like wet sugar and, as is also true of sugar, it has a lot of space between its granules. This means it can absorb meltwater in the way a sponge does. In the Journal of Glaciology this week, Peter Kuipers Munneke of Utrecht University in the Netherlands and his colleagues argue that this absorptive power is crucial to the stability of the world’s ice shelves—and therefore of the global sea level. That is because when the sponge is full, any surplus leaks into crevasses beneath the ice. There, it prises those crevasses further open, a process called hydrofracturing. Weaken an ice shelf enough in this way and it will disintegrate, as happened to the Larsen B shelf in Antarctica in 2002.

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