Previous episodes of sea-level rise, including during the Pleistocene, Holocene and recent past, offer a potential rich source of information to understand present sea-level behaviour and provide the basis to model possible future marine inundations resulting from climate changes. A response mechanism can be formulated, using this evidence from previous episodes of sea-level rise, to construct specific scenarios that may be projected using geographic information systems (GIS). Such palaeo-model projections can be evaluated against evidence from former higher Holocene shorelines and this approach is collectively termed the 'past-present-future' (PPF) methodology. This thesis considers the possibility of sea-level rise being oscillatory and how this may impact the formulation of future sea-level projections and the policy environment. Spectral analysis was undertaken on a range of sea-level records, temperature databases and other climate proxies in historical and Holocene records. A number of common periodicities were identified in both data sets (the recent and geological past), providing a basis to project past sea-level behaviour into the future. The existence of these common periodicities within a number of records suggests the presence of a complex rather than an exclusively linear response function as is currently assumed within climate models.