Shaped by distant storms and local winds, the waves reaching Ireland’s coast do not only carry energy, but also reflect the changing patterns of the climate – with growing impacts on coasts This idea is central to this thesis. As climate changes, ocean waves around Ireland will also change. These shifts affect both the offshore conditions and wave behaviour near the coast, including how far they run up onshore. Understanding these changes is crucial not only for protecting vulnerable coasts but also for supporting sectors such as offshore renewable energy and coastal planning. To investigate the evolving wave climate and its coastal impacts, a multi-scale approach is applied. The study integrates large-scale atmospheric processes with regional wave simulations and coastal-scale impact assessments. Statistical and numerical methods are combined to link oceanic variability in the North Atlantic to coastal responses around Ireland. A detailed analysis using lagged cross-correlation to swell period data estimates swell travel times and identifies source regions, forming the basis for selecting the North Atlantic domain for wave simulations. A nested WAM-SWAN modelling system, driven by surrogate wind fields generated for the winds from the MPI-ESM model together with sea ice and sea level inputs, captures the spatial distribution and projected changes in wave heights. To translate these offshore wave conditions into coastal impacts, a one-dimensional model is developed to simulate wave run-up for a selected site in Galway Bay. The results reveal that the projected changes in wind fields, storm activity, and sea level will continue shaping waves near the Irish coast. The findings demonstrate that Ireland’s coastal hazards cannot be assessed in isolation from the broader North Atlantic system or without considering local influences, underscoring the need for multi-scale approaches for managing future coastal risks around Ireland.