Quirks and Quarks

How the Greenland Ice Sheet is melting from the bottom up

The shape of the sea floor is flushing warm water underneath the glacier, so it is melting from above and below.

The shape of the sea floor is flushing warm water underneath the glacier, accelerating its melt

Rivers of meltwater flow off the 79 North Glacier in Greenland. (Janin Schaffer)

The ice sheet covering most of Greenland has been melting much faster in recent years, and scientists may now understand why.

A recent expedition led to the discovery that the shape of the sea floor is driving warm water under the glacier, melting it from below.

"There is as much heat going into the glacier, to melt the glacier from below, as 60 nuclear power plants would produce," oceanographer Janin Schaffer told Quirks & Quarks host Bob McDonald. "So it's really a massive amount of heat melting the glacier from below."

Schaffer and a team of researchers from the Alfred Wegener Institute in Germany were studying the coastal "ice tongues" of the 79° North Glacier in northeast Greenland. By mapping the sea floor, they discovered that a canyon is creating an underwater current, flushing warm water from the Atlantic towards the ice sheet, causing it to melt quicker than current models predicted.

A small research boat is seen in the water in front of the Greenland Ice Sheet. (Natalie Prinz)

Greenland's ice sheet is currently melting seven times faster than it did in the 1990's, and a recent study shows that this melt is the largest driver of global sea rise. It holds enough fresh water to raise global sea levels by more than 7 metres.

The team also studied a nearby ice tongue and found a similar feature on the sea floor.

"If these glaciers are getting unstable, the whole ice is flowing from the ice sheet faster into the ocean, and thus then adding a lot of freshwater into the ocean," said Schaffer. "It's definitely one little puzzle piece in a way to solve this, and also to now improve our ice sheet glacier ocean models."

The paper was published in Nature Geoscience.

Produced and written by Amanda Buckiewicz