Antarctica’s so-called Doomsday Glacier is dropping ice at its quickest fee in 5,500 years, elevating considerations concerning the ice sheet’s future and the opportunity of catastrophic sea degree rise brought on by the frozen continent’s melting ice.
The discovering comes from a research of prehistoric sea-deposits discovered on the shores surrounding the “doomsday” Thwaites Glacier and the neighboring Pine Island Glacier, each positioned on the West Antarctic Ice Sheet. The chilling information? Antarctica’s glacial soften, pushed by local weather change, is advancing sooner than ever earlier than in recorded historical past, researchers have reported June 9 within the journal Nature Geoscience (opens in new tab).
“These at the moment elevated charges of ice melting could sign that these very important arteries from the center of the West Antarctic Ice Sheet have been ruptured, resulting in accelerating movement into the ocean that’s doubtlessly disastrous for future international sea degree in a warming world,” co-author Dylan Rood, an Earth scientist at Imperial School London, mentioned in a press release.
“Is it too late to cease the bleeding?” Rood requested.
As certainly one of Antarctica’s fastest-melting glaciers, Thwaites has earned the nickname”Doomsday Glacier.” For the reason that Eighties, Thwaites has misplaced an estimated 595 billion tons (540 billion metric tons) of ice, contributing to a 4% rise in international sea ranges. Thwaites and its northern neighbor, the Pine Island Glacier, cowl huge expanses; Thwaites has a floor space of about 74,130 sq. miles (192,000 sq. kilometers) (making it almost as huge as Nice Britain) and Pine Island 62,660 sq. miles (162,300 sq. km).
Because the sea-facing ends of the glaciers are positioned above a bowl-like ocean basin, each glaciers are uncovered on their undersides to currents of heat, dense, salty water. This heat water is not simply melting the glaciers the place they lengthen into the Amundsen Sea, however additionally it is whittling away at them from beneath, unpinning them from their principal anchoring factors positioned to the north. Moreover, this soften from beneath weakens the glaciers and makes them extra susceptible to floor fractures, which may unfold throughout all the ice sheet, and doubtlessly trigger it to shatter. If everything of the West Antarctic Ice Sheet had been to interrupt up and soften into the ocean, it could elevate international sea ranges by roughly 11 toes (3.4 meters).
To check the glaciers’ soften charges right this moment with these of the distant previous, scientists seemed for clues on Antarctic seashores near the place the glaciers terminated on the ocean. Ice weighs down land, in order a few of that frozen weight melted and drained into the ocean towards the top of the final ice age (round 11,500 years in the past) the land rebounded to disclose shorelines that had been beforehand hidden beneath the waves. By measuring the ages and heights of almost two dozen shorelines, the scientists hoped to find how shortly ice disappeared from the land earlier than advancing once more.
The researchers estimated the ages of the shorelines by amassing historical shells and tiny fragments of penguin bones, earlier than analyzing the traditional biomatter with radiocarbon courting. This methodology identifies the age of natural materials by measuring the quantity of carbon-14, a radioactive carbon isotope, or variant with a distinct variety of neutrons, which is discovered all over the place on Earth and is well absorbed by vegetation and animals. When animals die, they cease accumulating carbon-14 of their tissues and the quantity that they’ve already absorbed begins to decay. The half-life of carbon-14 (or the time it takes for half of it to decay) is 5,730 years, and scientists can pinpoint the ages of animals that died 1000’s of years in the past by measuring portions of undecayed carbon-14 within the stays.
After courting penguin bones and shells from greater than 20 totally different shorelines, the scientists discovered that the oldest and highest seashore started to type roughly 5,500 years in the past. From that second in time till about 30 years in the past, ice loss uncovered the shorelines at a fee of about 0.14 inches (3.5 millimeters) every year, the researchers reported. However over the previous three many years, the speed of shoreline advance has skyrocketed — as much as 1.6 inches (40 mm) per yr.
“Though these susceptible glaciers had been comparatively secure through the previous few millennia, their present fee of retreat is accelerating and already elevating international sea ranges,” Rood mentioned.
What this implies for the way forward for Antarctica’s glaciers and ice sheet — and susceptible coastlines across the globe — is unclear. The researchers’ findings, whereas alarming, do not deal with what number of occasions the glaciers could have retreated and readvanced throughout recorded historical past. The scientists hope to determine this out by drilling by the ice to pattern rock of the landmass beneath it, which may present if the present fee of soften is reversible, or if the glaciers have really handed a degree of no return.
Initially printed on Dwell Science.
