Antarctica just lost another huge chunk of ice 4X the size of Manhattan - and that could be just the beginning

Antarctica just lost another huge piece of ice. The ice broke off of Pine Island Glacier, which is the fastest melting glacier on the continent.

Scientists first saw a large rift in the glacier's center last March. Six months later, one of the scientists tweeted that the rift had grown, causing a giant chunk four times the size of Manhattan to break off.

Since the ice chunk was part of a glacier, it will not raise sea levels. However, scientists say there's a bigger story here.

There's something unusual going on with Pine Island Glacier. It's melting differently from other parts of Antarctica.

Instead of breaking apart from the sides, the glacier is forming cracks in its center. These central cracks appear to form under the ice.

Scientists think this unusual behavior is due to warmer ocean waters. It could also be causing more rifts to form more often.

If this pattern continues, it could expose ice on Antarctica that will raise sea levels. Scientists aren't sure if or when this could happen.

In the meantime, there's not much they can do except watch the glacier break apart piece by piece.