Satellite video shows the ice shelf holding the Pine Island Glacier in Antarctica back from the sea is breaking up much faster than before.
A study Friday shows the ice shelf has shrunk by one-fifth since 2017.
That worries scientists because the large glacier protected by the shelf could collapse sooner than the centuries they had predicted.
When the shelf breaks up, it spawns icebergs 5 miles long and 22 miles wide, then those break into smaller ones.
Scientists say the crumbling of the shelf, captured on time-lapse satellite video, is triggered by climate change.