An international research group, including scientists from three French laboratories (1), has revealed the systematic and negative impact of ocean warming on the extent of ice shelves in the East Antarctic Peninsula in recent decades and the 9000 last years.
The Antarctic Peninsula is one of the regions most affected by the current global warming. Over the last 50 years, it has lost almost 75% of the surface of its floating ice platforms, which are important barriers to ocean erosion for the continental ice cap and, therefore, limit the sea-level increase. The major collapses of these platforms in recent decades coincide systematically with joint and rapid increases in ocean temperature (+0.3°C) and atmospheric temperature (+3°C).
Scientists conducted geochemical analysis of marine sedimentary records which were compared to data from an ice core located only 50km from their study site. With these temperature reconstructions covering the last 9000 years, they have shown that the main period during which all the platforms have been greatly reduced in the Eastern Antarctic Peninsula, between 8200 and 6000 years BC, occurred during a major oceanic warming (+1.5°C) period, while the atmosphere was cooling. They also pointed out that the progressive warming of the ocean (+0.3°C) over the last thousand years has recurrently controlled the gradual removal of the ice shelves of this region.
Based on this observation, this research team focused on assessing the possible evolution of ocean and atmospheric temperatures over the next century, based on two scenarios established by the Intergovernmental Panel on Climate Change (IPCC). Only the pessimistic scenario of increasing atmospheric (+3°C) and oceanic (+0.3°C) temperatures would be enough to weaken these ice platforms even more, until they can collapse completely in the coming decades. Their future therefore belongs henceforth to the respect or not of the Paris Agreements, and to its objectives of limiting global warming to +2°C.
Johan Etourneau, Giovanni Sgubin, Xavier Crosta, Didier Swingedouw, Verónica Willmott, Loïc Barbara, Marie-Noëlle Houssais, Stefan Schouten, Jaap S. Sinninghe Damsté, Hugues Goosse, Carlota Escutia, Julien Crespin, Guillaume Massé & Jung-Hyun Kim (2019) Ocean temperature impact on ice shelf extent in the eastern Antarctic Peninsula, Nature Communications, doi:10.1038/s41467-018-08195-6
Note (1) :
The French laboratories involved are the Laboratoire environnements et paléoenvironnements océaniques et continentaux (EPOC/OASU, Université de Bordeaux/CNRS/EPHE), the Laboratoire d’océanographie et du climat: expérimentations et approches numériques (LOCEAN/IPSL, CNRS/UPMC/IRD/MNHN), and Unité mixte internationale TAKUVIK (UL/CNRS).