The meltdown of Greenland's ice sheet is speeding up. Data from a US space agency (Nasa) satellite show that the melting rate has accelerated since 2004. If the ice cap were to completely disappear, global sea levels would rise by 6.5m (21 feet). Estimated monthly changes in the mass of Greenland's ice sheet suggest it is melting at a rate of about 239 cubic kilometres (57.3 cubic miles) per year. This figure is about three times higher than an earlier estimate.
(BBC online)