Relative sea-level rise and the influence of vertical land motion at Tropical Pacific Islands

Abstract : This study investigates the relative sea–level changes and the influence of vertical land movements at South Western Tropical Pacific Islands. The dataset consists of tide gauge records, remote satellite altimetry observations and GPS records. After evaluating the uncertainties and the nature of vertical land movements, we focus on the present and future relative sea–level changes. The main source of uncertainty comes from the types of vertical land motion estimates. Results revealed that the relative sea level has increased more than the global mean sea level (from 0.8 to 4.2mm yr–1 higher) overall in the region during the last 4–6 decades, especially at the islands located over the most tectonically active areas where future changes cannot be reliably projected. For most of the islands located outside tectonically active areas, relative sea–level projected changes by the end of the 21st century are of similar magnitude to the projected global mean sea–level (0.6 ± 0.2m in the RCP 8.5 scenario), with the exception of Tahiti where major changes are projected (0.8 ± 0.2 m).