1. Thermohaline Overtuning – at Risk? Detlef Quadfasel, THOR Project Office KlimaCampus, University of Hamburg, Germany http://www.eu-THOR.eu THOR.eu@zmaw.de Participating Institutes: University of Hamburg Germany, Max-Planck Gesellschaft Germany, British Meteorological Office UK, Université Pierre et Marie Curie France, University of Bergen Norway, The University of Reading UK, European Centre for Medium-Range Weather Forecasts UK, Leibniz-Institute of Marine Science at the University of Kiel Germany, Royal Netherlands Meteorological Institute Netherlands, Danish Meteorological Institute Denmark, Havastovan Faroe Islands, Marine Research Institute Iceland, Royal Netherlands Institute for Sea Research etherlands, The Centre for Environment, Fisheries and Aquaculture Science UK, Scottish Association for Marine Science UK, Natural Environment Research Council UK, Nansen Environmental and Remote Sensing Centre Norway, Centre National de la Recherche Scientifique France, Commissariat a l’Energie Atomique France, Finnish Institute of Marine Research Finland Facts and Figures Research focus: Stability of the ThermoHaline Circulation Duration: 4 years, December 2008 – November 2012 Number: 20 participating institutions from 9 European countries 5 Core Themes, around 60 Researchers Project cost: 12.95 million Euro EU Funding: 9.27 million Euro THOR will develop and operate an optimal ocean observing system for the North Atlantic component of the MOC. This observation system, consisting of arrays of self contained instruments as well as ship- and space-borne measurements, provide accurate time series of mass, heat and salt fluxes at key locations, allowing for the first time to assess the strength of the Atlantic MOC. Overflow volume transports in Denmark Strait and the Faroe Bank Channel show stable exchanges (1995-2009) Objectives Identify induced climate impacts of changes of the THC and the probability of extreme climate events Develop and operate an optimal ocean observing system for the North Atlantic component of the THC Forecast the Atlantic THC and its variability until 2025 Assess the stability of the THC to increased freshwater run-off from the Greenland ice sheets for various global warming scenarios. Time series of temperature in the central Labrador Sea shows an overall warming since 1994 Core Theme 1 MOC Variability Core Theme 3: Observations of the North Atlantic MOC 20-years Prediction Core Theme 2 Model Uncertainty Core Theme 5 Technological Advancements Core Theme 4 Predictability of MOC The variability of the ocean circulation in the North Atlantic has direct implications for the European climate, and for the global climate through its effects on the Atlantic Meridional Overturning Circulation (MOC). The EU- funded THOR project ("Thermohaline Overturning: at Risk?") aims at quantifying the range and probability of changes associated with MOC variability using palaeoclimate studies, long term observations and numerical models of ocean circulation. Twenty higher education and research institutions from 9 European countries cooperate under THOR. The project is divided into five core themes. Overflow Jet in Denmark Strait (red: southward flow) Mooring work in harsh weather Time series of MOC transport at 26° N show large seasonal and interannual variability Water sampling with CTD and Microstructure profiler Vertical Structure of the Meridional Overturning Circulation red: warm upper layer flows blue: cold deep currents