Scientists have watched as a crack in the Antarctic Peninsula’s Larsen C ice shelf has grown across the shelf, allowing a massive amount of ice to break away. Now that this new iceberg is free of the ice shelf, it will drift north into the Southern Ocean. Multiple smaller icebergs will also likely accompany the primary one, posing a threat to shipping routes near the southern tip of South America. The ice is expected to continue to drift into the south Atlantic or circulate around Antarctica, following the Antarctic Circumpolar Current.

This is what it looked like from space when the crack broke through the Larsen C ice shelf via @StefLhermitte (Delft University of Technology, The Netherlands)

Using satellites from the European Space Agency, scientists estimate that the iceberg covers 2,550 square miles, just slightly larger than the state of Delaware. With an average thickness of 625 feet, the iceberg will contain 277 cubic miles of ice.

This volume of ice is colossal and can be visualized several ways:

- It would coat all 50 states in a layer of ice 4.6 inches deep

- It would be a sphere of ice 8 miles high, literally edging into the stratosphere

- It would reach more than halfway to the way to the moon if squeezed into the area of a football field

- It would be slightly larger than the nucleus of Halley’s Comet (250 cubic miles)

The new iceberg will remove about 12 percent of the ice shelf’s area. Losing that much ice at once will likely change the way the remaining ice behaves. Most researchers don’t think that a collapse in the near future is likely, because of the large amount of ice Larsen C still has, but they’ll still be watching the ice shelf closely for signs of weakness.

An ice shelf is a floating area of ice adjacent to the land. Antarctica’s ice shelves act as doorstops that hold back glaciers and the continent’s vast stores of land ice. Once an ice shelf is removed, land ice can flow more easily into the sea. Because the Larsen C ice shelf and the new iceberg are already floating, the calving event does not add to sea level rise. However, if the remaining ice shelf collapses or starts losing mass more rapidly, it could effectively unplug the glaciers next to the shelf, sending land-based ice into the Southern Ocean, and contributing to sea level rise.

Most scientists have pinned the Larsen C crack largely on natural causes, though a few have suggested rising temperatures could have played a role. Recent massive calving events at Larsen C’s smaller neighbors do have a stronger link to climate change, though. The Larsen B ice shelf in 2002 and the Wilkins ice shelf in 2008 both saw huge icebergs break off due largely to warming waters. Larsen B collapsed shortly after its major calving event while the Wilkins ice shelf has continued to shed large chunks of ice since 2008.