Viewpoint Sea-level rise and coastal change: the past as a guide to the future Colin D. Woodroffe * , Colin V. Murray-Wallace School of Earth & Environmental Sciences, University of Wollongong, Wollongong, NSW 2522, Australia article info Article history: Received 3 February 2012 Received in revised form 21 April 2012 Accepted 2 May 2012 Available online 2 June 2012 Keywords: Sea-level rise Coastal change Timescales Shoreline behaviour abstract There is a broader awareness than ever that we live in a changing environment. The spectre of climate change is of wide concern, and the observed trends and anticipated consequences of an acceleration of sea-level rise pose a series of threats for the future of people who live in coastal communities. Coastal geoscientists are able to reconstruct the position of former sea levels; they can also explain much of the geographical variation in relative sea-level history. Successive collaborative projects (many under the auspices of international programmes sponsored by IGCP and INQUA) derived local sea-level histories and compiled atlases of relative sea-level curves, and some addressed past coastal behaviour in response to these changes. The most recent International Geological Correlation programme project 588, ‘Preparing for coastal change’, continues this impressive lineage of projects that have laid the foundations for our understanding of sea-level behaviour over the late Quaternary. Today, these issues are a major focus in the debate about climate change, its impacts, and the need for adaptation on the most vulnerable shorelines. There is clearly a role for the palaeoenvironmental skillset honed through successive geo- scientific projects. Investigations of past coastal environments have provided the tools for delineating past levels of the sea, but the stratigraphical and geochronological studies which were necessary to reconstruct the sea-level position also provide insights into where the shoreline lay and how the coast behaved as sea level changed. If the present is the key to the past, then the past, seen from the context of the present, can be a guide to the future. Collaborative projects and international co-operation between scientists from different disciplines can play important roles in future debates about how our world will change. First, the lessons learnt about the patterns of variation of relative sea level need to be more widely recognised by climate scientists. Efforts aimed at establishing the rate of future global sea-level rise need to be complemented by protocols to determine regional deviations from that mean rate of sea-level change. Second, modes of coastal change need to be identified to replace simplistic heuristics of coastal response, such as the Bruun rule. Simulation modelling offers a suite of tools that appear to give coastal managers guidance, but geoscientists should strive to produce evidence that can be used to develop and validate model behaviour. Coastal scientists presently have a relatively good understanding of coastal behaviour at millennial timescales, and process operation at contemporary timescales. However, there is less certainty about how coasts change on decadal to century timescales. It is these latter timescales which are particularly important for managers and policy-makers. These, and related challenges, provide a focus for research that will have a relevance for society that the coastal geoscience research community has rarely experienced. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The study of past sea levels (palaeo-sea-level studies) adds significantly to our understanding of the nature of sea-level vari- ability and provides a firmer foundation on which to base projec- tions of future sea-level change and the consequences for shorelines. Coastal geoscientists have put considerable effort into deriving stratigraphical and geochronological records of past sea- level and compiling Holocene sea-level curves from around the world, recognising that the pattern of relative sea-level change differs at different points on the Earth (Lambeck et al., 2010). Broad atlases of those relative sea-level curves have been compiled, but better understanding of the causes of variation at the local-scale (<1000 km) could play a significant part in deriving sea-level guidelines for planning. Still further research is needed to recon- struct the nature of past shorelines and provide insights into how different coasts have behaved in response to sea-level change. This research can serve as input into understanding and further * Corresponding author. Tel.: þ61 2 4221 3359; fax: þ61 2 4221 4250. E-mail address: colin@uow.edu.au (C.D. Woodroffe). Contents lists available at SciVerse ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev 0277-3791/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2012.05.009 Quaternary Science Reviews 54 (2012) 4e11