Colossal New Antarctic Iceberg Forming

An iceberg the size of New York City is expected to break away from a western Antarctic ice sheet any day now. Scientists have spotted an 18-mile-long crack in the sheet of floating ice in front of the Pine Island Glacier, and believe the sheet is about to calve a 310-square-mile iceberg, the BBC reports. The glacier has thinned in recent years, but scientists say the formation of this new iceberg is part of a natural cycle.

"The last big calving event occurred in 2001, so, in general, people have been expecting something like this to happen fairly soon, and for us it is very exciting to see this while it is happening," says a scientist working for NASA's IceBridge project, which is measuring the thickness of ice in polar regions. The iceberg will be tracked so ships can be warned, and the impact of its release of millions of tons of freshwater into marine environments can be measured. (More Antarctica stories.)