Pine Island Glacier in West Antarctica was grounded on a submarine ridge only a few decades ago, but warm ocean water now flows through the widening gap between the ridge and the ice, according to a study online this week in Nature Geoscience. The present changes at Pine Island Glacier could be part of a potentially unstable, long-term retreat, which could have implications for the possibility of wide-spread collapse of ice sheets in West Antarctica.
Adrian Jenkins and colleagues measured ocean and seafloor properties with an autonomous underwater vehicle that entered the cavity beneath the ice shelf off Pine Island Glacier. They found evidence for warm sea water flowing underneath the ice shelf, melting the ice. The result was a retreat inland of the grounding line ― the transition between land-based ice that does not affect sea level, and floating ice that does.
In an accompanying News and Views, Christian Schoof says: "The observations reported by Jenkins and colleagues provide exciting new insights into the processes that governed one of the fastest melt rates under an Antarctic ice shelf."