A giant iceberg about the size of Delaware that had been under scientists’ watch has broken off an ice shelf on the Antarctic peninsula and is now adrift in the Weddell Sea. The 2,200 square-mile, trillion metric-ton section of the Larsen C ice shelf “calved” off sometime between Monday and Wednesday, a team of researchers at Swansea University’s Project Midas has reported, citing imaging from NASA’s Aqua MODIS satellite instrument.