Glacier collapses
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Glacier collapse as satellites reveal sudden ice melt

25 July 2012 Last updated at 10:28 BST

Nasa has said satellites have recorded what it calls "unprecedented" surface melting in Greenland.

Scientists do not yet know if this a rare natural event or due to global warming.

It comes after a boat owner narrowly escaped a glacier collapse there two weeks ago.

Julie Peacock reports.