Retreat of Arctic ice has been so dramatic that atlases are being changed. Greenland’s ice sheets are also melting faster than we thought ,not on the surface, but due to currents below the ocean. While the loss of polar sea ice is troubling, the hidden sublimation of Greenland’s ice is of greater concern.
That’s because these continental ice sheets and glaciers hold up to 90 per cent of our fresh water on Earth. As Greenland’s ice warms in the summer, it pushes its way down through fjords and towards the ocean, where some of it breaks off into the sea. This is, of course, happening at an accelerated rate, too, an iceberg the size of Manhattan calved off of Greenland last week.
When the ice hits the ocean at sea level, it doesn’t melt that quickly, the water is literally ice-cold. But as NASA glaciologists looked deeper beneath the water, they saw that the thicker ice sheets were being carved away faster and more dramatically than they expected by warm currents pushing up from the tropics.