Warm ocean currents
As the direct cause of the melting of the ice sheets, the scientists point to the role played by ocean currents that changed as the climate became warmer. These shifts enabled warm ocean water originating from much warmer areas to reach Antarctica. The scientists link this development with the melting of the ice in Antarctica.
Much of today's Antarctic ice is also in contact with ocean water, explains lead researcher and first author Francesca Sangiorgi, Utrecht University: “In recent years, it has become increasingly clear that the stability of Antarctic ice not only depends on the temperature of the atmosphere, but that the temperature of the oceans also plays an important role. A higher concentration of CO2 not only entails warmer air temperatures, but also changes to the ocean currents. This research shows that warm ocean water could reach this area of eastern Antarctica, with evident consequences for the melting of the ice sheets.”
It is not inconceivable that pulses of warm water of this kind could still reach the South Pole, says Sangiorgi. “If the ice currently covering this area were all to melt, you would be faced with a rise in sea level of almost 15 metres.”
Francesca Sangiorgi is currently on a drilling exhibition in the Ross Sea, Antarctica with the Integrated Ocean Discovery Program. The expedition aims to gain a better understanding of the vulnerability of the Antarctic ice cap during climate changes in the distant geological past, in order to improve predictions of the future melting of the Antarctic ice cap.
This research is funded by the polar programme of the NWO (Netherlands Organisation for Scientific Research). The drilling expedition and the Dutch participation in it have partly been made possible by the NWO's contribution to the Integrated Ocean Discovery Program.
Southern Ocean warming and Wilkes Land ice sheet retreat during the mid-Miocene
Francesca Sangiorgi, Peter K. Bijl, Sandra Passchier, Ulrich Salzmann, Stefan Schouten, Robert McKay, Rosie D. Cody, Jörg Pross, Tina van de Flierdt, Steven M. Bohaty, Richard Levy, Trevor Williams, Carlota Escutia, Henk Brinkhuis. Nature Communications doi: 10.1038/s41467-017-02609-7