Impacts of sea level rise and adaptation across Asia and the Pacific

Abstract

Coastal communities worldwide face increasing risks from sea level rise (SLR) and more frequent coastal flooding, threatening densely populated areas. This study applies a Coastal Flood Risk Modelling Framework to evaluate permanent inundation from SLR and episodic flooding from extreme events across Asia and the Pacific, while also estimating the costs and benefits of adaptation. Using probabilistic projections of mean and extreme sea levels under five Shared Socio-economic Pathway (SSP) scenarios, ranging from ambitious mitigation (SSP1-1.9) to high fossil-fuel development (SSP5-8.5), the framework integrates hazard, exposure, and vulnerability data to estimate economic impacts. Current annual economic losses from coastal flooding in Asia and the Pacific amount to $26.8 billion, severely affecting Southeast Asia, South Asia, and the Pacific Islands. By 2050, expected annual economic damages are projected to rise between $143.7 and $197.8 billion just considering SLR effects (depending on the scenario), with further exacerbation by the century’s end. Atoll nations, including Kiribati, Maldives, RMI and Tuvalu will face the most severe losses relative to GDP. These findings underscore the urgent need for holistic adaptation measures including, grey, green and hybrid solutions, adaptive planning, resilient infrastructure, improved governance systems, alongside mitigation policies to reduce future emissions and consequent flood risks.