30/06/2025
An international study led by the Cnr-Institute of Polar Sciences (Cnr-Isp) and Ca’ Foscari University of Venice has revealed that at the end of the last glacial period, the deep Circumpolar Current rose along the margin of the Ross Sea, contributing to the retreat of the ice sheet. The research, published in Science Advances, lays the groundwork for predicting how the Antarctic ecosystem may respond to ongoing global warming
The ancient ice shelf in the Ross Sea—the largest on the planet—has been threatened by global warming not only today, but also around 18,000 years ago, at the end of the last Ice Age. This was revealed by an international study led by the Institute of Polar Sciences of the National Research Council of Italy and Ca’ Foscari University of Venice, in collaboration with scientific institutions from Italy, the UK, and Germany, including the Alfred Wegener Institute (Awi), the University of Plymouth, the National Institute of Geophysics and Volcanology (Ingv), and the University of Trieste. The article, published in Science Advances, demonstrates how warm waters from the deep Circumpolar Current reached the base of the Ross Sea ice shelf, playing a decisive role in its destabilisation and subsequent retreat.
“This is the first direct evidence that the deep Circumpolar Current—a warmer ocean current compared to typical Antarctic waters, and therefore capable of melting ice—was able to rise to the base of the ancient floating ice shelf in the Ross Sea, contributing to its breakup at the onset of post-glacial warming,” explains Chiara Pambianco, lead author of the paper, PhD student at Ca’ Foscari University of Venice and associate at Cnr-Isp. “Our study shows how ocean heat transport, driven by atmospheric circulation, was crucial in destabilising the Ross Ice Shelf.”
The research team analysed marine sediments collected from the Joides Trough, a strategic area located downstream of the ancient grounding line of the ice sheet in the western Ross Sea. By combining organic biomarkers, microfossils, and sedimentological analyses, the team reconstructed 40,000 years of ocean-ice interactions, identifying the intrusion of the deep Circumpolar Current shortly after the Last Glacial Maximum—around 20,000 years ago.
“We discovered that the intrusion of warm waters in this area is closely linked to a southward shift of westerly and easterly winds, which allowed deep water masses to rise onto the continental shelf, weakening the base of the ice shelf and promoting its collapse,” adds Tommaso Tesi, co-author of the paper and researcher at Cnr-Isp. “The ancient ice shelf was much more extensive than it is today, extending about 1,000 km further in the Ross Sea. With this work, we offer a new perspective on theprocesses that governed ice loss in Antarctica in the past—processes that are now being reactivated under the pressure of climate change.”The Ross Sea ice shelf is a crucial element for the stability of the Antarctic ice sheets, as it acts as a bridge between sea ice and continental ice.
“This shelf provides support and stabilisation for the inland ice masses. The intrusion of the deep Circumpolar Current can erode the base of the shelf, causing its retreat and, consequently, destabilising the continental ice it supports,” conclude Chiara Pambianco and Tommaso Tesi. “The ice-ocean system is therefore highly interconnected: changes in ocean currents can not only contribute to the melting of the Ross Ice Shelf but also lead to the loss of continental ice, potentially causing a sea level rise of over 60 metres. Understanding the dynamics that caused the reduction of this ancient shelf in the past is essential for predicting Antarctica’s future behaviour in response to global warming and, consequently, for forecasting future sea level changes”.
Giuliana Panieri, director of Cnr-Isp, emphasises: “This research involved advanced expertise and tools in a large-scale multidisciplinary investigation, highlighting the importance of international collaboration in understanding the changes taking place in Antarctica, and showcasing the contribution of a new generation of researchers”.
The study is the result of two projects carried out during the 2017 and 2023 campaigns of the Italian National Antarctic Research Program (PNRA), and of a collaboration between the Alfred Wegener Institute (AWI) and Cnr-Isp (PAIGE project).The PNRA is funded by the Italian Ministry of University and Research (MUR) and managed by the National Research Council of Italy (Cnr) for scientific coordination, by ENEA for logistical planning and operations at Antarctic bases, and by the National Institute of Oceanography and Experimental Geophysics (OGS) for the technical and scientific management of the icebreaker Laura Bassi.
Per informazioni:
Tommaso Tesi
Cnr-Isp
tommaso.tesi@cnr.it
Chiara Pambianco, Ca' Foscari University of Venice, Cnr-Isp, email: chiara.pambianco@unive.it
Ufficio stampa:
Cecilia Migali
Ufficio stampa Cnr
cecilia.migali@cnr.it
Responsabile Unità Ufficio stampa:
Emanuele Guerrini
emanuele.guerrini@cnr.it
ufficiostampa@cnr.it
06 4993 3383
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