The glacial North Atlantic Oscillation

Based upon coupled climate simulations driven by present day and glacial boundary conditions, we demonstrate that the glacial North Atlantic Oscillation was characterized by four distinct centres of action and thus by an atmospheric circulation that differed radically in terms of its internal variability from modern conditions. Moreover, we show that although simulated modern climate supports a coupled atmosphere-ocean mode characterized by a timescale near 30 years (so-called Atlantic Multidecadal Oscillation, AMO), this mode is predicted to be absent under LGM conditions.