Impact of ENSO on European Climate

The El Niño – Southern Oscillation (ENSO) affects many parts of the globe, particularly in the tropics where changes in rainfall and temperature due to the varying phase of ENSO are the single largest source of year-toyear change. Clear ENSO influences on the extratropics are found over North America and Australia but Atlantic links are much less clear. In this short paper we review some of the attempts to identify ENSO teleconnections to the Atlantic and Europe and unify some of the earlier studies to point to a clear ENSO teleconnection to the Atlantic basin. The main signal is for cold conditions over Northern Europe during El Niño and a circulation anomaly that corresponds to the negative phase of the North Atlantic Oscillation. Piecing together evidence from recent studies we show that there are at least two major pathways by which the tropical Pacific affects Atlantic-European seasonal climate. We also show evidence for non-linearity in the response that helps to explain the discrepancy between studies that focus on short time periods or individual events and those that include more comprehensive sets of ENSO events. Given the remarkable level of ENSO predictability already achieved in seasonal forecasts, these teleconnections offer the opportunity of at least a moderate level of predictability for Europe during active ENSO years.