SOURCE: The Washington Post, Yale e360

DATE: September 25, 2017

SNIP: An enormous Antarctic glacier has given up an iceberg over 100 square miles in size, the second time in two years it has lost such a large piece in a process that has scientists wondering whether its behavior is changing for the worse.

The Pine Island Glacier is one of the largest in West Antarctica, a region that is currently Antarctica’s biggest ice loser. Pine Island, which loses an extraordinary 45 billion tons of ice to the ocean each year — equivalent to 1 millimeter of global sea level rise every eight years — is 25 miles wide where its floating front touches the sea, and rests on the seafloor in waters more than a half-mile deep. The single glacier alone contains 1.7 feet of potential global sea level rise and is thought to be in a process of unstable, ongoing retreat.

The glacier is feared to be in a process of unstable, runaway retreat. The grounding line has been moving inland, and as it retreats, the seafloor bed dips downward, meaning that the ocean becomes even deeper and the ice becomes even thicker. Thus, further retreat should increase the rate of outward flow and lead to even more ice loss.