Emerging Predictability of Summer North Atlantic Oscillation and the Associated Euro-Atlantic Surface Climate in Recent Decades

Abstract:

The summer climate in the Euro-Atlantic region is of significant societal importance and is trending towards increased risk of extreme climate events such as heatwaves. The summer North Atlantic Oscillation, as the primary mode of atmospheric variability in this region, has been long considered lacking predictability on seasonal time scales, contrary to its winter counterpart. Here we show that the summer North Atlantic Oscillation has become predictable, even with a two-month lead, for the past several decades. This predictability may have been traced back to the North Atlantic warming hole and weakening of the Atlantic Meridional Overturning Circulation and does not extend further back in time before the accelerated ice melting in the boreal cryosphere associated with the Arctic amplification.