Ireland functions as a meteorological sentry post for much of north-western Europe, and it is in its vicinity that the skirmishes between air masses which determine the climatic fingerprints of much of the continent are often first observed, and their sting re·moved. It is here that the harbingers of weather for areas further east may be first assessed and the knowledge used to provide early warning of imminent weather events. The shelter effect of Ireland constitutes one of the principal controls on climate for much of Britain, and it is in the vicinity of Ireland that any significant changes in oceanic circulation associated with global warming in Europe will be first detected.