Antarctic glaciers continue to lose height
Scientists have used nearly a quarter of a century observations to show how West Antarctica’s glaciers are losing their height. Their satellite record shows the pace of change has increased with almost 7 meters being lost per year.
The most concerning glaciers are: Pine Island, Thwaites, Pope, Smith and Kohler. They all terminate in the Amundsen Sea and their melting has a significant impact on global ocean rise.
According to data from the Center for Polar Observation and Modelling (CPOM) the glaciers are now dumping between 120 to 140 billion tons of ice a year into the ocean. This is enough to push global waters by between 0.34mm and 0.40mm per annum, which is more than 10% of the global trend.
Among the reasons the glaciers are losing height is the warming of the seawater that surrounds them.
"As the glaciers accelerate, they have to take ever more ice from the interior to compensate for the speed-up. This means they thin; they lose height, which we can detect from space. And if there is no increase in snow and ice in the interior then this thinning will just migrate further and further upstream," explained Dr. Hannes Konrad from the CPOM to the BBC.
Dr. Konrad presented his work at the Fall Meeting of the American Geophysical Union (AGU)
“Glaciers draining the Amundsen Sea Sector in West Antarctica have been observed to be in a state of widespread dynamical imbalance throughout the satellite era, manifesting in retreat, acceleration, and thinning of their grounded portions. Satellite altimetry observations of these glaciers have been continuously available since the early 1990s. This uninterrupted record now allows us to assess the glaciers' response to sub-ice shelf melting, which is thought to be the main driver of the imbalance in this part of Antarctica,” says their presentation.
His team used measurements from five satellite altimeter missions form the European and American space agencies and obtained uninterrupted records of ice-sheet elevation change over the Amundsen Sea in West Antarctica since 1992.
Their research also showed each glacier from the five studied has a different behavior. For example, Pine Island Glacier is the one that contributes more to sea level rise and it thins steadily and relentlessly. The glacier loses in average 5m in height every year and the thinning spreads as far as 15km inland per year at times.
Instead Thwaites has had two broad periods of thinning. Its response is delayed and episodic which means the thinning hasn’t spread so far inland.
The study’s results will be used to try to forecast the behavior of the Amundsen Sea region and see the consequences it will have in a warming world and the future sea-level rise.