Eawag – Acquatic Research, January 4, 2011: “Examination of deep sea corals reveals that there have been drastic changes to oceanic currents in the western North Atlantic since the 1970s. The influence of the cold water Labrador Current, which is in periodic interchange with the warm Gulf Stream, has been decreasing continually since the 1970s. Occurring at the same time as Global Warming this phenomenon is unique in the past 2000 years. These results are reported by researchers from the University of Basel and Eawag in the current edition of the scientific journal «PNAS». One of the oldest known weather systems in the world is the North Atlantic Oscillation (NAO), the periodic variation of atmospheric pressure difference between the Azores and Iceland. It dictates not only whether the winters in Europe will be cold and dry or wet and warm, but also influences the oceanic currents in the North Atlantic. On the continental shelf off Nova Scotia, the NAO seems to control the interaction between different water masses. During positive phases, the oceanography of the north-west American continental shelf is dictated by a relatively warm water mass at 10 degrees Celsius which is salty and nutrient-rich, originating from the Gulf Stream. If the NAO is in a negative phase, the Labrador Current is dominant, a relatively cold water mass at 6 degrees Celsius, which is relatively nutrient-poor scarce and originates from sub-polar regions. Using new geochemical methods, an international team of researchers including the biogeochemists Prof. Moritz Lehmann (University of Basel) and Dr. Carsten Schubert (Eawag – Swiss Federal Institute of Aquatic Science and Technology) were able to prove that a drastic change to a «warm water mode» occurred in the western North Atlantic in the early 1970s. This change, the timing of which coincides with and may be directly related to Global Warming, is unique in the last 2000 years.”