Astronomical cycles, known as Milankovitch cycles, have strongly influenced the dynamics of the Antarctic ice sheet. This was revealed by a recent study, published in Nature Geoscience, conducted by INGV researcher Fabio Florindo in collaboration with an international team. The analyses, performed on marine sediments taken from the Ross Sea, a deep bay located in Antarctica between Queen Victoria Land and Marie Byrd Land, show a strong control of the obliquity cycle (inclination of the Earth's axis with respect to the perpendicular to the plane of the orbit) on the evolution of the Antarctic ice sheet over the last 34 million years.
Furthermore, the researchers point out, the influence of obliquity on the evolution of the ice sheet is amplified when the latter is more developed and extends into the sea, well beyond the coast line while sea-ice is reduced. Most probably the variations in the meridional temperature gradient, induced by the cycles of the obliquity, modify the position of the oceanic current that laps the continent by altering the heat input by this current. Based on these results, the researchers state that, with the current configuration of the obliquity cycle, if the sea ice cover decreases in the next decades due to the same process, there will be an increased heat input from ocean currents which will lead to a rapid decline of the Antarctic ice sheet along the continental margin.
The results obtained in this research support recent simulations on the dynamics of the Antarctic ice sheet which highlight that the stabilization or reduction of the CO2 input into the atmosphere is necessary to avoid the loss of ice sheets.
This type of research highlights the importance of studying the geological past to understand the response of the Earth system to climate change.
