A 2,239 square mile iceberg (roughly the size of Delaware) has broken off of Antarctica's Larsen C ice shelf. The chunk of ice weighs over a trillion tons.
Climate scientists have been monitoring the rift ever since the Larsen A ice shelf disintegrated in 1995. The Larsen B ice shelf also collapsed in 2002 following a similar calving event in 1995. It's possible that Larsen C will regrow and stay stable, but it's also possible it will meet the same fate as the other ice shelves.
Why it matters: Ice shelves are floating on water already, so they don't contribute to sea level rise. However, they act as sort of dams, keeping land-based glaciers from flowing into the sea. Such glacial flows could gradually contribute to sea level rise. Regardless of what happens, the geography of the Antarctic peninsula is forever changed.