Greenland’s ice sheet melted at a record rate in 2010, and this could be a major contributor to sea level rise in coming decades.

The ice in Greenland melted so much last year that it formed rivers and lakes on top of the vast series of glaciers that covers much of the big Arctic island, with waterfalls flowing through cracks and holes toward the bottom of the ice sheet. Take a look at video from Marco Tedesco of City College of New York, who is leading a project to study what factors affect ice sheet melting. The photo at left shows a camp by the side of a stream flowing from a lake – all of it on top of the ice sheet.

‘This past melt season was exceptional, with melting in some areas stretching up to 50 days longer than average,