The research challenges the classic hypothesis about the origin of the most powerful ocean current on the planet, which envelops and protects the white continent, and warns of its fragility in the face of global change.
The Circum-Antarctic Current works as a great engine regulating the planet’s climate. It had always been thought that its origin caused the formation of permanent ice in Antarctica about 34 million years ago, but now a work led by the University of Barcelona, ??the Andalusian Institute of Earth Sciences (CSIC) and Imperial College of London casts doubt on this theory and completely changes the understanding of how the Antarctic ice sheet developed in the past and what this could mean for the future of the planet as the climate changes.
The article published in the journal Nature Geoscience breaks with the classic view on the origin of the Antarctic Circumpolar Current, the largest marine current on Earth and decisive in ocean circulation and global climate.
The most powerful ocean current on the planet
“Until now it was thought that the polar current drove the formation of ice in Antarctica. Our study reveals that the oceanographic current is much later than the beginning of the Antarctic glaciation,” explains Professor Dimitris Evangelinos, first author of the study and member of the Consolidated Research Group in Marine Geosciences of the Faculty of Earth Sciences of the UB and Imperial College London.
“This discovery implies a whole change of scientific perspective in the world of Antarctic research on the interaction between the polar current and the Antarctic ice,” says the expert. “The findings also reveal that this current is very sensitive to changes in climate conditions, a condition that also puts the climate protection of the frozen supercontinent at risk.”
Teams from the Paleomagnetism Laboratory of the Scientific and Technological Centers of the UB (CCiTUB) and Geosciencies Barcelona (GEO3BCN-CSIC), the University of Granada, the University of Salamanca and the University of Bordeaux, among others, have also collaborated on the article.
A paradigm shift in Antarctic research
The scientific community has debated for years about the origin and characteristics of the Antarctic Circumpolar Current. In addition to connecting the three main basins of the Southern Ocean (Atlantic, Pacific and Indian), this mass of polar waters regulates the transport of nutrients and energy to low latitude regions.
“The Arctic is the planetary region with the greatest impact from global warming. In Antarctica the effects are not as intense. And this is partly explained by the thermal insulation generated by the Circum-Antarctic Current, which prevents the arrival of warm waters on the white continent,” explains Professor Isabel Cacho, from the Department of Earth and Ocean Dynamics of the UB.
This study challenges the most accepted hypothesis, which establishes the appearance of the Antarctic Circumpolar Current once plate tectonics separated the Antarctic continent from the South American continent and opened the Drake and Tasmanian passages to the Southern Ocean.
“This means that the ice in Antarctica was formed prior to the existence of the Circum-Antarctic Current,” says the researcher. “The new study provides evidence that this circumpolar current is not the cause of Antarctic glaciation, but rather the consequence of ice formation.”
The work opens new perspectives for understanding the interaction between the Antarctic Circumpolar Current and the Antarctic Ice Sheet. “Understanding how these mechanisms work is important to understand the current and future ocean dynamics of the Southern Ocean in times of the past, and more importantly, in the face of the challenge of climate change,” the experts conclude.
