Regional climate forecasts cannot yet be derived with confidence from general circulation models of the atmosphere, particularly in terms of projecting precipitation changes at middle latitude locations such as Ireland. This paper employs several large datasets relating to Irish precipitation and synoptic circulation types to examine past and present precipitation-circulation relationships. These relationships are then used to make preliminary inferences concerning likely changes in seasonal parameters in a greenhouse-warmed Irish climate. It is concluded that increases of 5-15% in winter precipitation will be accompanied by significant reductions in summer values, especially in eastern Ireland. These projections, allied to the global predictions concerning sea level rise are then used in an examination of some implications, particularly in civil engineering aspects of environmental management.