Greenland ice 'adding to rising sea levels'
Melting ice from the coast of Greenland could make a much bigger contribution to rising sea levels than has previously been thought, a new study suggests.
Scientists believe a previously overlooked side-effect of global warming could greatly increase the rate of melting of the vast Greenland ice sheet.
The ice covers 1.7 million square kilometres (656,000 square miles), an area three times the size of Texas.
If all the ice melted and flowed into the sea, oceans around the world would rise by as much as 6 metres (20ft), causing extensive damage to coastal communities.
While such a disaster is not expected to happen, ice losses from Greenland are predicted to contribute 22 centimetres (8in) to global sea levels by 2100.
The new findings related to lakes formed from melted ice and snow indicate that this figure may be significantly too low.
The study shows that as Arctic temperatures rise, Greenland will develop a rash of these "supraglacial" lakes which are expected to spread much further inland.
By 2060, the amount of land they cover could be double what it is today.
One key effect the lakes have, once they reach a critical size, is to drain through fractures in the ice to reach the ice sheet base.
Like a lubricant, the lake water causes the melting ice to slide more rapidly into the ocean.
The lakes also have a direct impact on ice sheet melting because, being darker than ice, they absorb more of the Sun's heat.
The scientists based their findings on observations of the ice sheet from European Space Agency satellites and predictions of future ice melting from a climate simulation model.