Abstract
Policymakers recognise the imminent threats of sea-level rise on coastal populations, infrastructure and biodiversity. To better prepare for future sea-level rise, sea-level projections are employed to guide the decision-making process. However, depending on the components of sea-level rise considered and statistical methods used, different sea-level projections for the same region can vary greatly. This uncertainty has implications for policymakers seeking to balance the costs of adaptation against the risks imposed by sea-level rise. With the wide array of scientific projections available today, we address two research questions: (1) which scientific approaches do policymakers commonly employ in their decision-making processes? (2) Are there gaps in the communication between scientists and policymakers? We examined the methodologies used in the projections of a series of sea-level rise assessment documents from Asia for the 21st century. Nine of the 15 East and Southeast Asian administrations had projections that were publicly available. Of these, six were published with the assistance of foreign organisations from UK, Australia and/or the United States, signallingperhaps a lack of sea-level expertise in the region. Some countries were apprehensive about sharing their projections, possibly out of concerns for national interests. Of the 12 projections examined, 11 adapted the methodologies of the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report; Hong Kong had the most up-to-date projections, using a methodology based upon the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC). Only Singapore considered projections involving plausible high-end (H++) scenarios for sea-level rise.