Antarctica’s so-called Doomsday Glacier is shedding ice at its fastest rate in 5,500 years, raising concerns about the future of the ice sheet and the possibility of catastrophic sea level rise of the sea caused by the melting ice of the frozen continent.
The discovery comes from a study of prehistoric marine deposits found on the shores surrounding the “apocalyptic” Thwaites Glacier and nearby Pine Island Glacier, both located on the West Antarctic Ice Sheet. The chilling news? Antarctic ice melting, driven by climate changeprogressing faster than ever in recorded history, researchers reported June 9 in the journal nature geoscience (opens in a new tab).
“These currently high rates of ice melt may signal that these vital arteries in the heart of the West Antarctic Ice Sheet have been ruptured, resulting in an acceleration of ocean flow that is potentially disastrous for the future global level of ice. sea in a warming world”, co-author Dylan Rood, Earth scientist at Imperial College London, said in a press release.
“Is it too late to stop the bleeding? Rood asked.
As one of Antarctica fastest melting glaciers, Thwaites has earned the nickname”apocalyptic glacier.“Since the 1980s, Thwaites has lost an estimated 595 billion tonnes (540 billion metric tons) of ice, contributing to a 4% rise in global sea level. Thwaites and its northern neighbor, Pine Island Glacier, cover huge areas; Thwaites has an area of approximately 74,130 square miles (192,000 square kilometres) (making it almost as large as Great Britain) and Pine Island 62,660 square miles (162,300 square km) .
Because the seaward facing ends of the glaciers are positioned above a bowl-shaped ocean basin, both glaciers are exposed on their undersides to currents of warm, dense, salty water. This warm water not only melts the glaciers where they extend into the Amundsen Sea, but also eats into them from below, detaching them from their main anchor points to the north. Additionally, this melting from below weakens glaciers and makes them more prone to surface fractures, which could spread across the entire ice sheet and potentially cause it to burst. If the entire West Antarctic ice sheet were to break up and melt into the sea, it would raise global sea levels by about 11 feet (3.4 meters).
To compare glacier melt rates today with those of the distant past, scientists looked for clues on Antarctic beaches close to where the glaciers ended in the ocean. The ice weighs down the land, so some of this frozen weight melted and flowed into the sea towards the end of the last ice age (about 11,500 years ago), the land rebounded to reveal shores that were previously hidden under the waves. By measuring the age and height of nearly two dozen shorelines, scientists hoped to find out how quickly the ice was disappearing from the land before advancing again.
The researchers estimated the age of the shorelines by collecting ancient seashells and tiny fragments of penguin bones, before analyzing the ancient biomatter with radiocarbon dating. This method identifies the age of organic matter by measuring the amount of carbon-14, a radioactive agent carbon isotope, or variant with a different number of neutrons, found all over Earth and is readily absorbed by plants and animals. When animals die, they stop accumulating carbon-14 in their tissues and the amount they have already absorbed begins to degrade. The half-life of carbon-14 (or the time it takes for half of it to decay) is 5,730 years, and scientists can determine the age of animals that died thousands of years ago. years by measuring the amounts of undecomposed carbon-14 in the remains. .
After dating penguin bones and shells from more than 20 different shorelines, scientists have found that the oldest and highest beach began to form around 5,500 years ago. From then until about 30 years ago, ice loss exposed shorelines at a rate of about 0.14 inches (3.5 millimeters) each year, the researchers reported. But over the past three decades, the rate of coastal advance has skyrocketed – up to 1.6 inches (40mm) per year.
“Although these vulnerable glaciers have been relatively stable over the past millennia, their current rate of retreat is accelerating and is already raising global sea levels,” Rood said.
What this means for the future of Antarctica’s glaciers and ice sheet – and vulnerable coastlines around the world – is unclear. The researchers’ findings, while alarming, do not specify how many times glaciers may have retreated and re-advanced throughout recorded history. Scientists hope to figure this out by drilling through the ice to sample the landmass rock below, which could show if the current rate of melting is reversible or if the glaciers have truly passed a point of no return.
Originally posted on Live Science.
#Antarcticas #Doomsday #Glacier #Hemorrhaging #Ice #Faster #Years #Ancient #Penguin #Bones #Reveal