Concerns about the ice sheet's future and the possibility of catastrophic sea level rise caused by the frozen continent's melting ice are being raised.
The finding comes from a study of prehistoric sea-deposits found on the shores around the "doomsday" Thwaites Glacier.
Climate change can be seen from space.
It's too late to stop the bleeding. "Do you know what I'm asking?" Rood asked.
One of the fastest- melting glaciers in the world is Thwaites. Thwaites has lost an estimated 595 billion tons of ice since the 1980's, which has contributed to a 4% rise in global sea levels. Thwaites has a surface area of about 192,000 square miles and Pine Island has a surface area of 62,660 square miles.
Both glaciers are exposed to currents of warm, dense, salty water as they are positioned above a bowl-like ocean basin. The warm water is melting the glaciers where they extend into the Amundsen Sea, but it is also stripping them from their main anchoring points. The melt from below weakens the glaciers and makes them more prone to break, which could cause the entire ice sheet to break. Global sea levels would rise by approximately 11 feet if the entire West Antarctic Ice Sheet were to break up.
To compare the melt rates of the glaciers today with those of the distant past, scientists looked for clues on the beaches close to where the glaciers ended. During the last ice age, which ended around 11,500 years ago, some of the frozen weight melted and fell into the sea, revealing previously hidden shorelines. Scientists hoped to find out how quickly ice disappeared from the land by measuring the ages and heights of nearly two dozen shorelines.
The researchers estimated the ages of the shorelines by collecting ancient shells and tiny fragments of penguin bones. The age of organic material can be identified by measuring the amount of carbon-14, a radioactive carbon, or variant with a different number of neutrons, which is found everywhere on Earth and is easily absorbed by plants and animals. Animals accumulate carbon-14 in their tissues and the amount that they've already absorbed begins to decay when they die. Scientists can determine the age of animals that died thousands of years ago by measuring quantities of undecayed carbon-14 in the remains.
After dating penguin bones and shells from more than 20 different shorelines, the scientists found that the oldest and highest beach was formed around 5,500 years ago. The shorelines were exposed at a rate of about 0.14 inches per year until about 30 years ago. Over the past 30 years, the shoreline advance has increased by up to 40mm per year.
The glaciers were relatively stable during the past few millennia, but their current rate of retreat is raising global sea levels.
It is not clear what this means for the future of the glaciers and ice sheet. The researchers don't address how many times the glaciers retreated and re-advanced across recorded history. If the current rate of melt is reversed or if the glaciers have passed a point of no return, the scientists hope to figure this out by drilling through the ice to sample the rock beneath it.
It was originally published on Live Science
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