The edge of an ice sheet on the coast of the vast continent is surrounded by the Southern Ocean. The image was captured in the year of 2017: Katharina Hochmuth is a student at the University of Leicester.
A sudden cooling event 34 million years ago contributed to the formation of the ice sheets.
The opening of the Southern Ocean seaways caused a reorganization of ocean currents, heat transport and a strong cooling of the surface water in the South.
The study was conducted by a team of researchers from around the world, and was published in Nature Communications. The results shed light on a 50-year-old question about how and why the ice sheets formed.
The co-author of the study said that they have heard a lot about modeling projections on our planet. In this paper, we show how important it is 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 the ocean gateway can cause a dramatic drop in coastal temperatures, and therefore the fate of the ice sheet.
The last land bridges connecting Australia and South America broke off 34 million years ago. The event left the polar continent isolated by other land mass and led to a reorganization of ocean currents in the Southern Ocean.
A circumpolar current stopped the subpolar gyres from transporting warm surface waters to the coast. The Earth underwent one of its most fundamental climate change events when ice sheets began to build on Antarctica.
The role of the opening seaways in the formation of ice sheets in the ocean has always been debated by scientists.
The study led by Dr. Isabel Sauermilch shows that the events were more closely linked than previously thought.
I was surprised to see how much high-resolution matters in an ocean model. These simulations are very sensitive to changes in the depth of the seaways and react differently than low-resolution simulations.
The turbulent ocean currents that are smaller than 100 km are crucial for the accurate temperature distribution in the Southern Ocean.
The simulations show that a small deepen of the Southern Ocean seaways by a few hundred meters caused a dramatic cooling of the surface waters. The first glaciation of Antarctica and the Earth's transition into an Icehouse world were affected by this tectonic event and declining atmospheric carbon dioxide concentrations.
The results of the study show the importance of tectonically-driven processes in the changing oceanographic and climatic conditions of the Southern Ocean.
Climate models that predict future climate conditions and to understand how the climate might behave under higher atmospheric carbon dioxide concentrations need to understand the ancient climate stages.
Isabel Sauermilch and her team show how the Gateway-driven weakening of ocean gyres leads to Southern Ocean cooling. There is a DOI: 10.1038/s41467-021-26658-1.
Nature Communications is a journal.
The cooling event that happened in the Southern Ocean was caused by atonic shift.
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