Greenland ice-melt 'speeding up'

In 2001 NASA scientists published a major study based on observations by satellite and aircraft.
It concluded that the margins of the Greenland ice-sheet were dropping in height at a rate of roughly one metre a year.
Now, amid some of the most hostile conditions anywhere on the planet, Carl Boggild and his team have recorded falls as dramatic as 10 metres a year - in places the ice is dropping at a rate of one metre a month.