A tectonic shift in the Southern Ocean caused the dramatic ancient cooling event
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Leicester/Canadian-Media: New research has shed light on a sudden cooling event 34 million years ago that contributed to the formation of the Antarctic ice sheets, https://phys.org/news reports said.
New research has shed light on a sudden cooling event 34 million years ago that contributed to the formation of the Antarctic ice sheets.
High-resolution simulations of ocean circulations show that the tectonic opening of Southern Ocean seaways caused a fundamental reorganization of ocean currents, heat transport and initiated a strong Antarctic surface water cooling of up to 5°C.
The study, conducted by an international team of researchers from the University of Leicester, the Netherlands, Australia, Germany, and Norway, is published in Nature Communications. The results shed new light on a 50-year-old question about how and why the Antarctic ice sheets formed.
Dr. Katharina Hochmuth, International Ocean Discovery Program (IODP) Research Associate at the University of Leicester, and co-author of the study, said, “In the last week and in the lead up to COP26, we have heard a lot about modeling projections on our planet’s future. In this paper, we show that it is crucial to include atmospheric CO2 conditions as well as appropriate geographies from the past to successfully model changing climates.
“A 600m change in the depth of an ocean gateway can cause a dramatic drop in coastal temperatures, and therefore, the fate of the Antarctic ice sheet.”
The last land bridges connecting Antarctica with its surrounding continents, Australia and South America, broke off about 34 million years ago. This tectonic event did not only leave the polar continent isolated by other land masses; it also led to a major reorganization of ocean currents in the Southern Ocean.
A circumpolar current started to flow, preventing subpolar gyres from transporting warm surface waters to the Antarctic coast. At the same time, ice sheets started to build on Antarctica and the Earth underwent one of its most fundamental climate change events, transitioning from…