This Week’s Roundup: Glaciers are being collected in Antarctica, “quietly transforming the Earth’s surface” and causing floods
A team of scientists, aware of the need to obtain ice cores from threatened glaciers, are working to create a glacier archive bank in Antarctica
From CNRS News: “By capturing various components of the atmosphere, ice constitutes an invaluable source of information with which to examine our past environment, to analyze climate change, and, above all, to understand our future. Today, the science of ice cores lets us study dozens of chemical components trapped in ice, such as gases, acids, heavy metals, radioactivity, and water isotopes, to name but a few…”
“We plan to store the boxes in containers at a depth of 10 meters below the surface in order to maintain the glacier cores at an ambient temperature of – 54°C. The Antarctic is in fact an immense freezer with an ice sheet up to 4 kilometers thick, and is far removed from everything; in addition, it is not subject to any territorial disputes. The subterranean chamber will be large enough to house samples taken from between 15 and 20 glaciers.”
Study finds that ancient melting glaciers are causing sea levels to drop in some places
From Smithsonian Magazine: “But a new study out in the Journal of Geophysical Research shows that in places like Juneau, Alaska, the opposite is happening: sea levels are dropping about half an inch every year. How could this be? The answer lies in a phenomenon of melting glaciers and seesawing weight across the earth called ‘glacial isostatic adjustment.’ You may not know it, but the Last Ice Age is still quietly transforming the Earth’s surface and affecting everything from the length of our days to the topography of our countries.”
Glacial flood emerges along Iceland’s Skaftá river
From Iceland Magazine: “A small glacial flood is under way in Skaftá river in South Iceland. The Icelandic Met Office (IMO) warns travelers to stay away from the edge of the water as the flood water is carrying with it geothermal gases which can be dangerous….The discharge of Skaftá at Sveinstindur is presently 270 cubic metres per second. The flood is not expected to cause any downstream disruption.”
On July 20, 2010, researchers from Swansea University in Wales were setting up equipment near Helheim Glacier in Greenland when they happened to witness a 4-kilometer crack in the ice forming that extended from one side to the other. Quickly, they set up a time-lapse camera to record one of the largest glacier calving events ever filmed. They knew that they glacier advanced rapidly, achieving speeds as high as 30 meters per day, but they had not expected a sudden event.
As the split in the ice grew, it thrust the front part of the glacier into the ocean with great force. It rotated and flipped over into the ocean in the seconds before the glacier front fully broke off and floated away. Once the separation was complete, the ocean was filled so thickly with chunks of ice it was impossible to see the water.
This film and other data form the basis of a new study that was published last month in the journal Nature Geoscience, “Buoyant flexure and basal crevassing in dynamic mass loss at Helheim Glacier.” The researchers, Timothy D. James, Tavi Murray, Nick Selmes, Kilian Scharrer and Martin O’Leary, found the ocean itself is breaking up the glaciers. In plainer English, when a glacier reaches the sea, the front will float, bending the ice and creating crevasses at the bottom, causing the front of the glacier to snap off. These crevasses are much harder to detect that the ones on the surface, so their role had not previously been understood. The bending of the surface was a second discovery. The team used a stereo camera to record subtle elevation changes over two summers, capturing details that previous cruder calving studies had missed.
Scientists had long known that when a glacier calves, it breaks off into the ocean. They knew as well that this ice leads to sea level rise, a seemingly straightforward process. And now they have a fuller understanding of the hows and whys of glacier calving. This knowledge is important, because most of the Greenland’s glacial ice loss over the next 200 years is expected to be from such breaking off of ice into the ocean. Armed with a clearer grasp of the calving process, researchers will be better able to produce better models of ice dynamics and sea level rise—of importance to the billions who live in coastal areas, far from Helheim but intimately connected to it.