I was aware that there were new efforts ongoing to map the bedrock beneath the Greenland Ice sheet, and this video describes part of that effort and the results.
One issue that glaciologists are trying to sort out is, with much of the interior of Greenland below sea level, what is the vulnerability of those areas to inflow by seawater that might gradually undermine the ice sheet?
Forget about exploring other planets — it looks like Earth has a few surprises left. How about a massive canyon buried underneath an ice sheet?
Researchers announced Thursday, in the journal Science, the discovery of a massive canyon below an ice sheet that covers Greenland. The canyon is at least 750 kilometers long and 800 meters deep, in some parts. Its scale is being compared to the Grand Canyon in Arizona.
Scientists believe the canyon predates the ice sheet that has kept it hidden from the world, which is estimated to be a few million years old. The researchers are in awe that a discovery of this scope can still be made on Earth.
“With Google Streetview available for many cities around the world and digital maps for everything from population density to happiness one might assume that the landscape of the Earth has been fully explored and mapped. Our research shows there’s still a lot left to discover,” Jonathan Bamber, professor at Bristol’s School of Geographical Sciences and lead author of the study said in a press release.
The scientists used thousands of kilometres of airborne radar data, collected mainly by NASA and researchers from the UK and Germany over several decades, to piece together the landscape lying beneath the ice sheet that covers most of Greenland and obscures it from view.
At certain frequencies, ice is transparent to radio waves which can travel through the ice and bounce off the bedrock underneath. By analysing all the radar data in a consistent way the team discovered a continuous bedrock canyon that extends from almost the centre of the island and ends at its northern extremity in a deep fjord connecting to the Arctic ocean.
They believe the canyon plays an important role in transporting sub-glacial meltwater produced at the bed from the interior to the edge of the ice sheet and ultimately into the ocean. Even before the presence of the ice sheet, going back at least four million years, the evidence suggests the canyon provided a pathway for water from the interior to the coast and was a major fluvial system.
Both Jason Box and Mike MacCracken have mentioned the issue to me – and I included it in the “Ring of Mountains” video last spring.
Other deep troughs in the ice sheet have led to areas of fast flowing outlet glaciers like the Jakobshavn. In this case it has not, why not? Is it too deep and narrow, too far north, or not oriented correctly?
Isn’t Peterman glacier running pretty fast? I think this one communicates with the Peterman fiord.
It does communicate with Petermann. Petermann does not move particularly fast until close to the grounding line. At that it moves faster than the surrounding ice for quite some distance, which is why it is the most important glacier in NW Greenland. Note the two velocity graphs in the assessment of Petermann Glacier. The flow does not extend nearly as far inland at a high speed as Jakobshavn or 79 Glacier.
Some ocean warming news
World ocean heat content and thermosteric sea level change (0 – 2000 m), 1955 – 2010
We have estimated an increase of 24 x 10^22J representing a volume mean warming of 0.09C of the 0–2000 m layer of the World Ocean. If this heat were instantly transferred to the lower 10 km of the global atmosphere it would result in a volume mean warming of this atmospheric layer by approximately 36C (65F).
http://climatestate.com/2013/09/02/world-ocean-heat-content-and-thermosteric-sea-level-change-0-2000-m-1955-2010/