A remote village in Greenland is being threatened by a massive iceberg. Video captured a large piece of the iceberg breaking off and crashing into the water last week.

There are fears another breakaway chunk could trigger a tsunami.

Evacuations have already started in the town of Innaarsuit. The village on Greenland's west coast is home to only 169 people and more than 30 of them have already had to move to higher ground. When the iceberg calves, chunks of it fall into the sea and powerful waves surge into the harbor. If the warm weather means the berg breaks up faster or, worst of all, rolls over, the town could be flooded.

Greenland's ice has been on the move. A chunk half the size of Manhattan broke off the Helheim Glacier on the country's east coast last month. The spectacular event was captured by husband and wife climate-science team Denise and David Holland from New York University.

The Hollands have spent decades studying Greenland's ice and have never seen anything like it.

"It was really extraordinary," Denise said. "The sound was like a sonic boom or a thunderstorm."

"Warmer air and more important warmer water leads to rapid disintegration of ice," David said. "And icebergs are very unstable structure."

The calving of icebergs off Greenland's glaciers isn't new. The question is whether it's speeding up because the Arctic seas are warming and what that means.

How quickly the icebergs break off the glaciers and how fast they float out to sea and melt will determine how quick sea levels rise across the planet. Icebergs like the Helheim Glacier and the monster stuck off Innaarsuit are the future.

The residents of Innaarsuit are watching the berg. And watching the thermometer.