Arctic sea ice is vanishing much faster than generally expected, according to preliminary data from European Space Agency satellite Cryosat.

UK scientists combined results from Cryosat, which uses radar to measure ice thickness, with data from Nasa's IceSat, which uses lasers.

Their preliminary analysis suggests an annual ice loss of up to 900 cubic km a year from 2004.

Projections of Arctic ice melt vary widely.

But the new results are some 50% higher than projected in most scenarios.