A large rift is widening across an increasingly fragile Antarctic ice shelf, scientists found. The crack is spreading across the Larsen C Ice Shelf at an increased rate, threatening to carve out an iceberg the size of Delaware while destabilizing a larger area of ice roughly the size of Scotland. When this iceberg calving event happens — no one knows exactly when it will occur, except that it's getting closer — it will be the largest calving event in Antarctica since 2000, the third-biggest ever recorded and the largest from this particular ice shelf, scientists say. About 10 to 12...