Developing robust adaptation strategies to climate change impacts poses serious challenges resulting from competing objectives. For example, SLR will increase the risk of permanent and temporary flooding of low-lying coastal land, increasing the need for coastal protection. At the same time, sea level rise will change the distribution of vulnerable coastal ecosystems so their movement should be facilitated to ensure they are plentiful.

Yet, protection built for inundation can have negative impacts on ecosystems because of “coastal squeeze”. We then assessed the  impacts and trade-offs between different SLR adaptation strategies using geographic information system (GIS) and systematic planning software (Marxan with Zones).

The study found that sea level rise will negatively impact urban areas and lead to losses of some ecosystems, but will also provide opportunities in terms of potential total ecosystem expansion. Trade-offs between development and conservation can be quantified and minimised by incorporating information on decisions of future ecosystem and urban change. We can measure the uncertainty involved in the trade-offs based on the uncertainty in SLR predictions, by assessing the trade-offs given different SLR predictions. In this case study, the most cost-effective approach is one that includes both retreat and defence.