It's like watching 'Manhattan breaking apart in front of your eyes', says filmmaker James Balog. He's describing the largest iceberg calving ever filmed, as featured in his movie, Chasing Ice. After weeks of waiting, the filmakers witnessed 7.4 cubic km of ice crashing off the Ilulissat glacier in Greenland. Chasing Ice, released in the UK on Friday, follows James Balog's mission to document Arctic ice being melted by climate change.