From Rising Seas to Economic Ruin: ADB Warns of $739 Billion Coastal Flooding Risk by 2100

The Asian Development Bank warns that coastal flooding in Asia-Pacific could cause up to $739 billion in annual losses by 2100, threatening over 400 million people, critical infrastructure and economic growth. Investing $9 billion–$19 billion annually in coastal protection could prevent $178 billion–$360 billion in damages, highlighting the urgent need for stronger government policies, international financing and private-sector investment.

The Asian Development Bank (ADB), in its Asia–Pacific Climate Report 2026: Coastal Risks on the Rise—Actions for a Resilient Future, has warned that rising sea levels and worsening coastal floods could cause annual economic losses of up to $739 billion across Asia and the Pacific by 2100. The report highlights growing threats to more than 400 million people living within 10 kilometres of coastlines that generate approximately $7 trillion in economic activity annually. It calls for urgent government action, stronger international financial support and increased private-sector investment to protect infrastructure, livelihoods and long-term economic growth.

Coastal Flooding Could Trigger Massive Economic Losses

The report estimates that annual coastal flooding damages, currently around $27 billion, could rise to $172 billion–$199 billion by 2050 and reach $520 billion–$739 billion by 2100 without adequate adaptation.

Sea levels in parts of the western tropical Pacific are rising by approximately six millimetres annually, increasing the danger of flooding, erosion and saltwater intrusion. Rapid urbanization is making the situation worse. Between 1985 and 2015, coastal settlements expanded by 66.8%, while settlements exposed to flooding increased by 92.3%.

Major coastal cities, including Mumbai, Kolkata, Bangkok and Jakarta, face growing risks to transport networks, housing, electricity systems and commercial infrastructure.

The economic consequences extend beyond physical damage. Coastal disasters could disrupt ports and shipping networks, putting an estimated $40 billion–$45 billion in annual trade value at risk. Agriculture, fisheries and tourism also face mounting pressure from saltwater intrusion, ocean warming and coastal ecosystem degradation.

For businesses, these threats could mean higher insurance costs, supply-chain disruptions, damaged assets and declining investment returns.

Governments Must Put Climate Resilience at the Centre of Development

The ADB's findings suggest that coastal protection must become a core part of national economic planning rather than remain limited to environmental policies.

Governments need to strengthen coastal zoning regulations, improve drainage systems, enforce climate-resilient building standards and prevent unplanned development in high-risk areas.

Countries such as India, Bangladesh, China and Vietnam face significant challenges because large populations, industrial centres and essential infrastructure are concentrated along vulnerable coastlines.

The report also highlights the unequal social consequences of climate change. Climate-related welfare losses could reach 3.8% of household consumption in the Maldives, 2.7% in Kiribati and approximately 2.6% in Tonga and the Federated States of Micronesia.

Women, low-income households and coastal communities dependent on agriculture and fisheries are particularly vulnerable. Climate pressures could push approximately 124,000 women in the Pacific into food insecurity by 2030.

Governments therefore need to combine physical coastal protection with social protection, early warning systems, livelihood support and community-based adaptation.

Adaptation Financing Offers Major Opportunities for Development Partners

Despite rising risks, the report presents a strong economic case for investing in coastal resilience.

Annual coastal protection investments of approximately $9 billion–$19 billion could prevent an estimated $178 billion–$360 billion in annual damages. This suggests that early adaptation could deliver benefits many times greater than its costs.

However, financing remains inadequate. Adaptation needs for 15 coastal developing economies alone are estimated at approximately $20 billion annually.

International public adaptation finance increased from around $5 billion in 2015 to $11.4 billion annually during 2022–2023, but the available funding remains insufficient.

For multilateral development banks, international donors and climate finance institutions, the findings highlight the need to expand concessional loans, grants, technical assistance and climate-resilient infrastructure financing.

Development partners can also help governments prepare investment-ready projects, strengthen climate risk assessments and improve access to international funding.

Innovative financial instruments, including blue bonds, disaster insurance and blended finance, could attract additional capital while reducing the financial burden on vulnerable countries.

Private Investment and Stronger Policies Will Shape Coastal Resilience

The growing demand for adaptation creates opportunities for infrastructure developers, engineering companies, insurers, technology providers and financial institutions.

Potential investment areas include flood protection systems, resilient ports, coastal monitoring technologies, improved drainage networks, sustainable construction and mangrove restoration.

However, private investors also face significant risks. Coastal assets could lose value as flooding becomes more frequent, while inadequate climate risk assessment could expose companies to costly disruptions.

The report highlights different approaches already being pursued across the region. Singapore is strengthening long-term coastal protection planning, Bangladesh is implementing its Delta Plan 2100, and Fiji is addressing relocation challenges in highly exposed communities.

Looking ahead, the ADB calls for coordinated policies that combine infrastructure investment, ecosystem protection, improved governance and community participation.

Governments should integrate climate risks into national budgets and development plans, while international partners should provide predictable, long-term financing. Private businesses must assess climate exposure before making major investment decisions.

The report's central message is clear: investing in coastal resilience today is far less costly than paying for climate-related destruction tomorrow. With potential annual flooding damages approaching $739 billion by 2100, timely cooperation among governments, development institutions and businesses will be essential to protect economic growth, reduce poverty and secure the region's future.