Satellite imagery shows two of the fastest-changing glaciers in Antarctica fracturing than ever. The first step towards the glaciers collapsing and resulting in rise in sea levels.
With the aid of studies from ESA, NASA and USGS satellites, the researchers scoured the Pine Island and Thwaites Glaciers in the Amundsen Sea Embayment: two of the greatly strong glaciers on the Antarctic continent, and those accountable for a considerable 5% of global sea level rise.
Jointly, the two glaciers comprise an area of drifting ice the size of Norway, and carry sufficient water to lift the global sea levels by over a meter. Their morphology has been altered over the decades together with transition in atmospheric and oceanic conditions and the warming oceans causing ice shelves to melt and thin.
Foreseeing how these major glaciers will unfold in future is important to comprehend the prospect of our seas and our warming planet.
However, predictions are uncertain and computer models can’t fully account for the glaciers’ processes and properties in their predictions.
“To reveal what’s really going on at Pine Island and Thwaites, we dug into imaging data from a number of different satellites,” says Stef Lhermitte of Delft University of Technology in the Netherlands, and lead author of the new study.
“We found structural damage at the ‘shear margins’ of the glaciers’ ice shelves, where the ice transitions from fast- to slow-moving: large crevasses, rifts and open fractures that indicate that the ice shelves are slowly tearing apart. Currently, the ice shelves are a little like a slow car in traffic: they force anything behind them to slow down. Once they’re removed, ice sitting further inland will be able to speed up, which in turn will cause sea levels to rise even faster.”
This cracks didn’t appear in imagery from 1997, and the effect seems to be obvious in the imagery from 2016. This is an indication that the breakdown was stimulated over the past two decades and has become considerably worse in the last few years.
“This fracturing appears to kick off a feedback process—it preconditions the ice shelves to disintegrate,” explains co-author Thomas Nagler of ENVEO in Innsbruck, Austria. “As the glaciers fracture at their weak points this damage speeds up, spreads, and weakens more of the ice shelves, causing further deterioration—and making it more likely that the shelves will start crumbling apart even faster.”
“The results from this study highlight a pressing need to include such feedback processes in model projections of ice shelf retreat, ice sheet mass loss, and sea level change,” Mark Drinkwater, ESA’s Mission Scientist for CryoSat, and Senior Advisor on polar and cryosphere science explained.
“We know that a significant amount of glacial ice in West Antarctica is currently being affected by climate change—in fact, a recent study found 24% of this ice to be rapidly thinning and unstable. These new results underline just how quickly this damage is occurring, and reveal that Pine Island and Thwaites Glaciers are more vulnerable than ever before.”