Over the last 20 years, Greenland has been losing more ice than it gains through snowfall in winter– a change in a natural balance that normally keeps the ice-sheet stable. But warmer conditions are encouraging algae to grow and darken the surface. And since dark ice absorbs more solar radiation than clean white ice, it’s warming up and melting more rapidly.

Algae were first observed on the Greenland ice sheet more than a century ago, but until recently its potential impact was mostly ignored. Only in the last few years have researchers started to explore how the microscopically small plants could affect future melting.

Currently, the Greenland ice sheet is adding up to 1mm a year to the rise in the global average level of the oceans. If it all melted, the average sea level would rise around the world by about seven meters, or more than 20 ft.

“We suspect that in a warming climate these dark algae will grow over larger and larger parts of the Greenland ice sheet and it might well be that they will cause more melting and an acceleration of sea level rise,” said Prof Martyn Tranter of Bristol University, who is studying the ice sheet.

Learn more @ BBC