An international group of geologists has revealed when Antarctica’s Thwaites Glacier, dubbed the “Doomsday Glacier”, began to retreat. Estimates of the change in World Ocean level vary greatly: from five to six centimeters in 2100 to 2.5-2.9 meters in 2500. The thing is that there is currently no clear understanding of how glaciers will respond to climate change. There is speculation that the severe melting of Thwaites Glacier (“Doomsday Glacier”) could destabilize the western part of the Antarctic Ice Sheet.

Thwaites Glacier is so named because when it melts, it can raise the level of the World Ocean by 60 centimeters. According to 2019 data, its contribution to the overall increase in this level is 4 percent. The glacier is located in West Antarctica and its area is approximately equal to the Altai Region. It is believed to have melted due to warm circumpolar deep waters. Accelerating ice loss has been observed since the 1970s, but until now it remained unclear exactly when it started.

A group of geologists from the USA and the UK decided to find out where to calculate the current melting stage of the “doomsday glacier”. To do this, they collected marine sediment cores from different depths along the melt front. Analyzes using computer programs, tomography and other methods showed that thinning of the ice shelf began at least in the 1940s. An article on this subject was published in the magazine. Proceedings of the National Academy of Sciences.

Cores of sedimentary rocks up to six meters long were collected in the summer of 2019. The depth of their formations varies between 450 and 750 meters. The researchers extracted cores from different locations—a shallow area near the northern edge of the glacier tongue, a small depression on the western side, and others. Based on the collected data, geologists interpreted the process of precipitation accumulation.

The deposits around Thwaites document long glacier stability from the early Holocene (11,700 years to present) and ice retreat throughout the 20th century, the authors say. This was indicated, for example, by glacial debris, meltwater clouds, and deposits from the nearby Pine Island Glacier. Geochronological analysis of one of the cores showed that the Doomsday glacier began to break away from the sea in 1944±12 and finally broke away around 1970±4.

The researchers concluded that the Thwaites Glacier, along with Pine Island, began to retreat in the mid-20th century. According to the authors, this testifies to the climate sensitivity of the region and explains the synchrony of changes with the long El Niño of 1939-1942.

“What’s particularly important about our study is that these changes are not random or specific to just one ice. “They are part of the broader context of a changing climate,” said author Rachel Clarke.