Madrid, Jul 4 (EFE).- Permanent glaciation of Antarctica began some 34 million years ago in its eastern region, but it took another seven million years to reach the entire continent, which might explain why, at present, the ice is melting faster, especially in the western region.
An international team of researchers, with the participation of the University of Granada, has published 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.
About 34 million years ago, 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 one that still influences global climate conditions today.
The ongoing global warming is causing Antarctica’s eternal ice sheets to melt faster than previously thought, with the acceleration occurring most in West Antarctica. The root cause of this phenomenon might 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 started somewhere in East Antarctica,” while the other remained ice-free during that first glacial maximum, according to study leader Johann Klages, a geologist at AWI.
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 regarding 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 all it takes to melt the West Antarctic ice once more, and that’s exactly where we are now.”aclaró Klages.
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 might once once more 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.
#glaciation #Antarctica #began #million #years #eastern #part
2024-07-06 13:17:15
