Annual damage from coastal flooding in Asia and the Pacific could rise from around $27 billion today to as much as $739 billion by 2100 unless countries invest in adaptation measures, according to a new report by the Asian Development Bank (ADB).
The report, Asia-Pacific Climate Report 2026: Coastal Risks on the Rise—Actions for a Resilient Future, estimates that annual flood damage across 30 coastal economies could reach $172 billion to $199 billion by 2050 and $520 billion to $739 billion by 2100 without adequate adaptation.
However, annual investment of $9 billion to $19 billion in coastal protection could keep flood damage close to current levels and avert an estimated $178 billion to $360 billion in losses each year, the report says.
Released on Wednesday, the report warns that the region’s coastlines, which generate around $7 trillion in annual economic output, face growing threats from rising sea levels and intensifying climate-related hazards.
“Coasts are the overlooked engine-room of Asia and the Pacific’s growth but are retreating in the face of rising seas and escalating hazards,” said Yevgeniy Zhukov, director general of ADB’s Climate Change and Sustainable Development Department.
“We are at a turning point and must act now with long-term, adaptive, and risk-informed solutions to create resilient coasts that keep people safe and economies running,” he added.
More than 400 million people in ADB’s developing member economies with coastlines live within 10 kilometres of the sea, representing more than one in 10 people in those economies.
Coastal areas support ports, trade, tourism and heritage sites, making them vital to regional economies. While large economies could face some of the highest losses in absolute terms, the relative impact could be far more severe for small atoll nations.
Under a high-emissions scenario, annual flood damage in these island nations could amount to 30% to 60% of gross domestic product by 2100.
Major coastal cities, including Bangkok, Jakarta, Kolkata and Mumbai, could also experience a sharp increase in flooding. Floods that historically occurred once every 100 years could become annual events in these cities by the end of the century.
Disruptions to ports pose another significant economic risk, with around $40 billion to $45 billion in annual losses at stake across the region.
To address these threats, the ADB report urges governments to incorporate climate adaptation into development planning, strengthen institutions and governance, mobilise financing, and ensure sustained implementation and local ownership.
It recommends linking immediate action with long-term development goals while keeping policies flexible enough to respond to evolving climate risks.
International adaptation finance for coastal economies in Asia and the Pacific rose from around $5 billion in 2015 to an annual average of $11.4 billion in 2022 and 2023.
Despite this increase, a substantial financing gap remains, the report says.
Public finance will remain the foundation of coastal resilience investment, but governments will need to expand fiscal space and mobilise additional public, private and concessional funding to meet long-term needs.
Founded in 1966, the ADB is a multilateral development bank supporting sustainable and inclusive growth across Asia and the Pacific. It is owned by 69 members, including 50 from the region.