OCEANS Existing cooperation between France and Argentina concerning climate issues: ARGAU+GEF PATAGONIA SHN/CIMA - LOCEAN Aim: Biogeochemical and physical interactions, with emphasis on CO2 fluxes, in the southwestern Atlantic and Southern Oceans, field work completed , analysis ongoing FREPLATA (CIMA, INIDEP, INA, SHN - IFREMER) and IMFIA/SOHMA (UY) Observation and modeling of the fine sediment fluxes in the Río de la Plata (ongoing) Financed by FFEM DRAKE SHN/UBA - LOCEAN Transport and fluxes of the ACC in the Drake Passage SAMOC SHN/UBA - Université de Bretagne Occidentale South Atlantic Meridional Overturning Circulation Mesoscale variability studies in the Confluence Region CIMA - LOCEAN recently started cooperation

Motivation Frame: The western South Atlantic plays a key role in the climate system: Determines the contribution of cold vs warm water pathways of the Meridional Overturning Circulation Hosts a unique ecosystem which impacts on the biogeochemical cycles of the southern hemisphere oceans, the regional and global climate Observe and understanding the processes which drive climate variability and change Even with the large errors that the coupled climate prediction models have nowadays, these models should be used to study future scenarios of ocean circulation and its impact on ocean biogeochemistry It is necessary to observe the changes in the ocean circulation and variability Sparse atmospheric and ocean observations are a serious limitation; observations are needed for model validation. EXISTING INITIATIVES (OOI, PIRATA SWE, DRAKE, etc) Impact of the ocean circulation on the atmospheric variability Variability of ocean circulation and its impact on: biogeochemical cycles and productivity climate variability and change (fisheries, erosion)

Motivation Frame: The western South Atlantic plays a key role in the climate system: Determines the contribution of cold vs warm water pathways of the Meridional Overturning Circulation Hosts a unique ecosystem which impacts on the biogeochemical cycles of the southern hemisphere oceans, the regional and global climate

Scientific questions: ¿To what extent the main forcings of ocean circulation are changing and how will they change in the future? e.g. winds, boundary currents, fresh water and heat fluxes; waves; feedbacks ¿How is the circulation in the South Western Atlantic evolving? E.g. potential displacement of the confluence; mesoscale activity; shelf circulation (circulation here is very sensitive to winds and therefore we can expect changes); circulation in semienclosed areas ¿Which is the amount of the CO2 uptaken in the Patagonian shelf that is buried in the sediments? There are indications that a portion not yet quantified of the CO2 uptaken by the ocean is buried in the sediments. Quantification! ¿Which are the sources of nutrients and micronutrients which sustain the exceptional productivity of the Patagonian shelf and south-western Atlantic and which is their relative importance? E.g. dust; continental runoff; volcanic reactions; sediments; anthropic origin nutrients (fertilizers); groundwaters.  connection to climate change; sensitivity to climate change ¿How are the biogeochemical properties changing?

¿What's the impact of the changes on coastal zones and fisheries? There is evidence of strong erosion in several coastal regions of Argentina (e.g. Samborombón Bay) which seems to be associated to climate variability/change. Fishes life cycles are affected by climate variability/change through changes on temperature, nutrients, continental runoff, etc. Changes on tides, winds and waves can change the biodisponibility of contaminants in shallow zones; they can be eventually exported to the deeper ocean. Those changes can also affect sedimentation, particularly in shallow areas, as RDP (dredging needs, Paraná River delta advance) Changes on the ocean biodiversity  changes might be negative for some species but good for others (e.g. jellyfish); changes on biodiversity can, in turn, change climate  feedbacks Climate change might induce new diseases in ocean life and/or make ocean life vectors of new diseases, ¿how will it propagate to human population? Euthrofication as a consequence of the increase in the availability of nutrients in the rivers connections with the ocean ¿Effects on birds?

Recommendations: Contact with state holders, politicians, decision makers Communication is very important; results must reach society (science translation) UMI should consider to have people devoted to that

Also, we denote that the planning of the mentioned studies implies 1.Observations and modelling 2.The development of expertise at a local level 3.Formation of human resources The UMI should take into account these key components

Challenges 1.Field experiments 2.Improve models and further application of models 3.The development of expertise at a local level on the application of modelling tools and the analysis of global model solutions; biogeochemical models; earth system modeling 4.Formation of human resources The UMI should take into account these key components