Wednesday, July 16, 2008

DISAPPEARING LAKES

In late July 2006, a 2.2 square mile lake on top of the Greenland Ice Sheet emptied from the bottom through a crack that reached down to the base of the ice sheet, 3.215 feet below. Most of the 11.6 billion gallons of water drained away in 90 minutes.
Researchers documented the complete drainage of this supraglacial lake, one of thousands that form each spring and summer as sunlight melts snow and ice on the ice sheet. It's been long speculated that these lakes can build up enough pressure to crack their bottoms creating conduits to penetrate through the ice where the water greases the skids between ice and ground speeding up the glacial flow towards the ocean. More flow, more icebergs.
Supraglacial lake, Greenland Ice Sheet

Woods Hole Oceanographic Institution glaciologist Sara Das led and expedition to Greenland in 2006 and 2007. The object was to determine whether melting at the ice surface which is sensitive to climate change could influence how fast the ice can flow. If Greenland's 2-mile-thick ice sheet melts completely it would raise global sea level by 23 feet. It would add larger amounts of fresh water to the ocean which might affect ocean currents which can alter rainfall patterns, fisheries and climate

Sarah Das, Glaciologist

The team used seismic instruments, water level monitors and GPS sensors to monitor the evolution of two supraglacial lakes and the motion of the surrounding ice sheet.
The also used helicopter and airplane surveys and satellite imagery to monitor the lakes and track the progress of glaciers towards the coast. The team returned in July 2008 for a third summer of field work which you can follow here

Large ice canyon with melt water stream, Greenland



I blogged about Greenland lakes in 2006 here .


8 comments:

Brian Hughes said...

"It's been long speculated that these lakes can build up enough pressure to crack their bottoms"

That'd be the baked bean and cabbage diet.

Lord Sedgwick said...

Broyan, I blame the Jerusalem arty-farty-chokes.

River said...

Mother Earth has a mighty, mighty thirst.

Dysthymiac said...

absolutely beautiful sapphire BLUE ... are you sure that ice canyon is not in Bombay?

JahTeh said...

Youse two are disgusting. I couldn't think of eating anything worse than baked beans, cabbage and Jerusalem artichokes. Ghastly.

River, Greenland could end up a green land again.

Dys, I bought us two lovely gin glasses on special. They hold about 400 mls with room for the ice and the limes and a splash of tonic.

Mikhela said...

depressing

JahTeh said...

Mikhela, about the little people and their carbon footprints, Safeway today had asparagus from Peru, garlic from Argentina and mangoes from Mexico.

River said...

I love baked beans and cabbage. Not together in the same meal.