How urbanization enhanced exposure to climate risks in the Pacific: A case study in the Republic of Palau

The increasing risk of coastal flooding and water shortage in Pacific Island Countries is usually attributed to climate change hazards. This ignores other risk components, exposure and vulnerability, of which a major contributor is urbanization. We develop simplified analyses that can be applied to other PICs. By dividing climate risks into hazard and exposure components we determine how urbanization contributed to present-day risks and then predict how growing climate change hazards may increase future risk, using the Republic of Palau as a case study. Results show that urbanization was responsible for 94% of the buildings exposed to coastal flooding today. Projected sea level rise, 30.2 cm by 2050, only increased exposure of today’s buildings by 0.5%. In both present and future scenarios exposure resultant from urbanization was more significant than sea level rise. Our water scarcity index showed urbanization caused 3 of the 7 recorded water shortages from 1980–2018. From 2041–2079, analysis of projected rainfall showed mean reductions between 1.6–16.6% and increased variance between 0.3–3.4%. This led to three times as many water shortages under present population levels. In historical and future scenarios exposure from increased population was just as significant in causing water shortages as rainfall variation. These findings suggest that urban management is an important tool to lower exposure to coastal flooding and water shortage and we recommend that decision makers prioritize urbanization within climate risk policy in Pacific Island Countries.