HOLOCENE SEA-LEVEL RECORDS: DRIVING MECHANISMS AND COASTAL RESPONSES

The global sea-level community is now well-equipped to develop local, regional and global records of Holocene relative sea-level change. It is also increasingly able to describe linkages between terrestrial, coastal and marine environments through the application of new techniques of sediment finger-printing, dating, as well as quantitative models of coastal change, sea-level change and sediment flux. These high quality sea-level records have validated glacial isostatic adjustment models, thereby increasing our knowledge of Earth's rheology and ice sheet accumulation. Furthermore, rates of Holocene sea-level change have been compared with the historical and present day changes, providing an essential benchmark to measure against the additional sea-level rise that has occurred over the last 100 years.

However, the sea-level community has been less successful in determining the driving mechanisms of the patterns we observe and reconstruct. This is despite the coastal zone having a rich sediment and landform archive, presenting a superb opportunity for studying interactions and determining driving mechanisms over a range of spatial (global to local) and temporal (millennia to years) scales. Future research, through IGCP 495, will have two dimensions: the vertical dimension of relative sea-level change; and the lateral dimension of changing shoreline position. These changes in the coastal zone result from external forces (such as sea-level and climate change) and internal forces (including the coastal sedimentary budget), both of which we will address through hypothesis testing and model building. Under the first dimension, IGCP 495 will develop high-resolution (centimeter to meter scale vertical resolution and annual to centennial scale age resolution) records of vertical changes in relative sea-level that can be meaningfully compared with other local, regional and global environmental records derived from terrestrial and marine environments. The second dimension will use a combination of geological and archaeological data to better understand the interaction of terrestrial and marine processes in controlling lateral changes in shoreline position. This will require close co-operation with workers in related disciplines, including those focused on fluvial and nearshore environments.