Concluding a months-long deathwatch, one of the largest icebergs ever seen finally separated from Antarctica’s Larsen C Ice Shelf sometime in the last couple days. The 5,800-square-kilometer iceberg contains over a trillion tons of ice. For years, researchers have been keeping an eye on a growing rift in the floating ice shelf that raced toward completion in recent months.

The last piece of the #LarsenC breakup is nicely shown in high resolution in #Sentinel1. Farewell iceberg A68! @ESA_EO @MIDASOnIce pic.twitter.com/FUzZUlT4E8 — Stef Lhermitte (@StefLhermitte) July 12, 2017

The Larsen C Ice Shelf is composed of floating ice at the front of glaciers on the narrow Antarctic Peninsula. The breaking off of icebergs from shelves—a process called “calving”—is normal, though icebergs of this size are obviously rare. While warmer water or air temperatures have been an important factor in controlling the size of many Antarctic ice shelves, there’s no indication that climate change has played a significant role in the calving of this specific iceberg.

Because ice shelves are already floating, the melting of icebergs does not appreciably affect sea level (although there is a small contribution because melting icebergs dilute the saltiness of seawater).

However, ice shelves can help hold back the flow of the glaciers on land behind them, as they're often in contact with the sides of bays or against high spots on the seafloor. The glaciers behind the Larsen C Ice Shelf are not nearly as large as those elsewhere around Antarctica, but it’s possible (though not certain) that their shrinkage could eventually speed up because of this loss from the ice shelf.

Researchers on the Project MIDAS team studying the shelf wrote that “although the remaining ice shelf will continue naturally to regrow, Swansea researchers have previously shown that the new configuration is potentially less stable than it was prior to the rift. There is a risk that Larsen C may eventually follow the example of its neighbour, Larsen B, which disintegrated in 2002 following a similar rift-induced calving event in 1995.”

A view of the newly-formed #larsenc iceberg in #Antarctica, taken at 03:00 UTC this morning by the @NASANPP satellite. pic.twitter.com/nn7j2uGFMU — Simon Proud (@simon_rp84) July 12, 2017

The newly unmoored behemoth of an iceberg could be around for many years, depending on how quickly it breaks apart and drifts northward into slightly warmer waters.