Scientists have accurate estimates of the position of the retreating ground line, thanks to satellites that track small changes in ice altitude. But they don’t have a clear picture of the belly of the glacier yet like at the grounding line, because it’s thousands of feet of ice. “These data are really exciting because we’re looking at a hidden system,” said glaciologist Christine Dow of the University of Waterloo, who studies Antarctic glaciers but was not involved in the study. save, said.
Video: ITGC/Schmidt/Washham
With Icefin, researchers can remotely control the camera while measuring the salinity, temperature and oxygen content of the water. “We found that the ice bed itself has very complex topography, so there are a lot of stairs, terraces, cracks and crevices,” says physical oceanographer Peter Davis of the British Antarctic Survey. , said lead author of one of the papers and co-author of the study. other. “The rate of melting on different surfaces is very different.”
Where the underside of a glacier (or base layer of ice, in scientific parlance) is smoother, melting is certain to occur, but at a much slower rate than where there is jagged terrain. That’s because a layer of cold water sits where the ice is flat, insulating it from warmer ocean water like a loose blanket. But in places where the terrain is steep and uneven, there are more vertical surfaces where warm water can attack the ice, including intruding from the side. This melting creates a distinctive “scallop” shape, like the surface of a golf ball.
These extensive, complex underlying characteristics can then affect the rest of the ice. “If you open up the features underneath the ice, you get the same reflections of them on the surface, because of the way the ice floats,” Davis said. “So there’s a concern that if you widen these cracks and crevices under the ice, you could destabilize the ice shelf, which could lead to greater disintegration over time.”
