Global warming has accelerated the melting of Antarctic ice sheets, especially in West Antarctica. An international research team led by the Alfred Wegener Institute discovered that this discrepancy could be due to the formation of these ice sheets.
Sediment samples from drill cores, combined with climate and ice-sheet modeling, show that permanent glaciation in Antarctica began around 34 million years ago, initially in East Antarctica. The ice did not advance towards West Antarctica until at least 7 million years later, as detailed in their study published in Science.
Around 34 million years ago, Earth experienced a climate shift from a greenhouse world to an icehouse world, influencing current global climate conditions. However, the onset of glaciation in Antarctica has been ambiguous due to limited data, especially from West Antarctica.
Researchers from the Alfred Wegener Institute, British Antarctic Survey, Heidelberg University, Northumbria University, and MARUM—Center for Marine Environmental Sciences, among others, closed this knowledge gap. They used a drill core retrieved with the MARUM-MeBo70 seafloor drill rig offshore the Pine Island and Thwaites glaciers. This core showed no evidence of ice during the initial glaciation phase.
“Permanent glaciation must have started in East Antarctica,” said Dr. Johann Klages, geologist at the Alfred Wegener Institute. West Antarctica remained ice-free during this phase, covered by dense forests and a cool-temperate climate.
East and West Antarctica Response Differences
AWI paleoclimate modelers used new data alongside existing temperature and ice occurrence data to understand where the first permanent ice formed. The simulation supported the core findings, revealing that initial ice formation occurred in East Antarctica’s Northern Victoria Land, where moist air masses reached the Transantarctic Mountains.
“About seven million years later, conditions allowed ice to advance to West Antarctica,” explained Hanna Knahl, paleoclimate modeler at AWI. These findings show how differently East and West Antarctica respond to climatic changes.
“Even slight warming can cause West Antarctic ice to melt again, which is our current scenario,” added Klages.
Using New Technology for Insights
The knowledge gap was bridged using a unique drill core retrieved during the 2017 Polarstern expedition in West Antarctica. The MARUM-MeBo70 drill rig, used for the first time in Antarctica, successfully drilled into the seabed off West Antarctica’s Pine Island and Thwaites glaciers, retrieving valuable samples.
More information: J. P. Klages, Ice sheet-free West Antarctica during peak early Oligocene glaciation, Science (2024). DOI: 10.1126/science.adj3931
Original Story at phys.org