How heat is transported to Greenland glaciers

March 29th, 2011 - 5:47 pm ICT by ANI  

London, March 29 (ANI): A new study has shed light on how heat is transported to Greenland glaciers.

Warmer air is only part of the story when it comes to Greenland’s rapidly melting ice sheet. New research by scientists at Woods Hole Oceanographic Institution (WHOI) highlights the role ocean circulation plays in transporting heat to glaciers.

Greenland’s ice sheet has lost mass at an accelerated rate over the last decade, dumping more ice and fresh water into the ocean. Between 2001 and 2005, Helheim Glacier, a large glacier on Greenland’s southeast coast, retreated 5 miles (8 kilometers) and its flow speed nearly doubled.

A research team, led by WHOI physical oceanographer Fiamma Straneo,discovered warm, subtropical waters deep inside Sermilik Fjord at the base of Helheim Glacier in 2009.

“We knew that these warm waters were reaching the fjords, but we did not know if they were reaching the glaciers or how the melting was occurring,” said Straneo, lead author of the new study on fjord dynamics.

“People always thought the circulation here would be simple: warm waters coming into the fjords at depth, melting the glaciers. Then the mixture of warm water and meltwater rises because it is lighter, and comes out at the top. Nice and neat,” said Straneo.

“But it’s much more complex than that.”

The fjords contain cold, fresh Arctic water on top and warm, salty waters from the Gulf Stream at the bottom. Melted waters do rise somewhat, but not all the way to the top.

“It’s too dense,” said Straneo.

“It actually comes out at the interface where the Arctic water and warm water meet.”

This distinction is important, adds Straneo, because it prevents the heat contained in the deep waters from melting the upper third of the glacier.

Instead, the glacier develops a floating ice tongue-a shelf of ice that extends from the main body of the glacier out onto the waters of the fjord.

The shape of the ice tongue influences the stability of the glacier and how quickly it flows.

In addition, the team found that vigorous currents within the fjord driven by winds and tides also play a part in melting and flow speed.

“The currents in the fjord are like waves in a bath tub,” said Straneo.

“This oscillation and mixing contribute to heat transport to the glaciers.”

The study has been published online in the journal Nature Geoscience. (ANI)

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