Yale Environment 360: A massive chunk of Antarcticas fastest-moving ice stream, the Pine Island Glacier, dropped into the Amundsen Sea this week, nearly two years after scientists first observed a crack in the glacier tongue.German scientists, who have been tracking the progress of the ice mass since NASA satellites first observed the crack in October, 2011, say the calved iceberg measured 720 square kilometers (278 square miles), or about the size of the city of Hamburg. There is no conclusive proof that climate change...