Summary
How the Southern Ocean has and will in the future respond to anthropogenic CO2 induced climate change has been the subject of extensive in-situ measurements, satellite monitoring as well as modelling. Many uncertainties however remain in models of SO nutrient trapping, including the requirement of the SO biologic pump to overcome iron and light limitations as well as its response to ocean warming. Given the limitations of observational records, examining past conditions using geochemical proxy data is the only means to trace long-term trends, essential to effectively constrain the complex ocean-atmosphere-biosphere interactions, and hence the cause and effect processes that modulate climate. Such records, extracted from the skeletons of marine organisms with continuous chronologies extend not only into the pre-industrial era but also through geological time during periods of major climate change, which provide important insights into the oceans natural responses to and controls on the climate system.

Objectives
The project aims at 1) deconvolving anthropogenic versus natural variations changes in the Southern Ocean nutrients supplies occurring over short (decadal) to intermediate (centennial) timescales from the present-day through preindustrial times; 2) reconstructing ocean chemistry, hydrodynamics, and the evolution of CO2 during the Anthropocene and Last Glacial Maximum and deglaciation; 3) reconstructing changes in the temperatures of SO deep waters during the Anthropocene and Last Glacial Maximum and deglaciation and 4) reconstructing changes in water mass circulation during the Last Glacial Maximum and deglaciation.

Project Partners
• University of Western Australia
• CNR - ISMAR

Main Publications
• Trotter J., Taviani M., Foglini F., Sadekov A., Skrzypek G., Mazzoli C., Remia A., Santodomingo N., McCulloch M., Pattiaratchi C., Montagna P. (2020) First insights into Southern Ocean-facing submarine canyons off southwest Australia. Frontiers in Marine Science. In press

Other informations: • The FK200126 cruise

Figures
• F1 Paolo Montagna (CNR-ISP): Photo collected by the Remotely Operated Vehicle SuBastian at 867 m in the Bremer canyon systems (SW Australia) during the cruise FK200126 on board R/V Falkor, showing the large limid bivalve Acesta with solitary corals and barnacles (© Schmidt Ocean Institute)
• F2 Paolo Montagna (CNR-ISP): Photo of the deep-water coral species Desmophyllum diathus used as a climate archive to reconstruct annually-resolved records of temperature, pH, seawater chemistry and nutrient concentration.