Madrid – The permanent glaciation of the Antarctica It began about 34 million years ago in the eastern part of the continent, but it took another seven million years to reach the entire continent, which could explain why the ice is currently melting faster, especially in the western region.
An international team of researchers, with the participation of the University of Granadapublishes in Science a study on how and when the current Antarctic ice sheet was formed, thanks to the recovery of unique geological samples and sophisticated modelling models.
About 34 million years ago, the Earth experienced the transition from a greenhouse world, with little or no continental ice accumulation, to an ice world, with large areas permanently glaciated. This was one of the most fundamental climate changes and still influences global climate conditions today.
Current global warming is causing Antarctica’s eternal ice caps to melt faster than previously thought, with the acceleration occurring most rapidly in West Antarctica. The root of this phenomenon could lie in their formation, according to the team, led by the Alfred Wegener Institute (AWI).
The researchers based their work on a core drilled from the seabed in front of the Pine Island and Thwaites glaciers, on the coast of the Amundsen Sea (West Antarctica), to establish for the first time in history the origin of the Antarctic frozen continent.
The study indicates that no evidence of the presence of ice was found in the western region during the first major phase of Antarctic glaciation.
This means that “The first large-scale permanent glaciation must have begun somewhere in East Antarctica”while the other remained ice-free during that first glacial maximum, according to the study leader, Johann KlagesAWI geologist.
At that time, the western region was still largely covered by dense broadleaf forests and a temperate-cold climate that prevented ice formation.
To better understand where the first permanent ice formed in Antarctica, paleoclimate modelers combined the new data with existing data on air and water temperatures and ice formation.
The basic climatic conditions for the formation of permanent ice, according to the study, only existed in the coastal regions of northern Victoria Land and from there the ice sheet spread rapidly into the interior of East Antarctica.
It took about seven million years for conditions to allow an ice sheet to advance to the western coast of Antarctica.
The research also shows that the two ice sheet regions react very differently to external influences and fundamental climate changes.
“A slight warming is enough to cause the West Antarctic ice to melt again, and that is exactly where we are now,” Klages said.
The study thus provides new knowledge that allows climate models to simulate more accurately how permanently glaciated areas affect global climate dynamics, that is, the interactions between ice, ocean and atmosphere.
For Kalges, this is of crucial importance, “especially considering that we could once again face such fundamental climate change in the near future.”
The researchers were able to reach these conclusions with the help of a unique drill core they recovered during expedition PS104 on the research vessel Polarstern in West Antarctica in 2017.
The MARUM-MeBo70 drilling rig was used for the first time in Antarctica.
The seabed of the Pine Island and Thwaites glaciers in West Antarctica is so hard that conventional drilling methods have previously been impossible to reach deep sediments, so the MARUM-MeBo70, a new rig designed for this purpose, was used for the first time.