Key Details
ADB’s Asia–Pacific Climate Report 2026 examines how rising coastal hazards and the location of new development together shape exposure across 30 coastal developing economies. Its 2100 figures are scenario projections, not predictions of a certain outcome.
India: Under a high-emissions scenario, an estimated 21.5 million people could be affected by coastal flooding in an average year by 2100, including more than 4 million in Mumbai. The measure counts expected exposure to flood depths exceeding 15 centimetres; it does not mean the same people will necessarily flood every year.
Regional damage: Estimated annual coastal flood damage is about $27 billion today. Without additional adaptation, it could reach $520 billion under an intermediate-emissions scenario or $739 billion under a high-emissions scenario by 2100.
Development in exposed areas: From 1985 to 2015, coastal settlement area expanded 66.8%, while settlement in flood-exposed coastal areas grew 92.3%.
Protection investment: ADB estimates that $9–19 billion a year across its developing member economies in coastal flood protection could keep annual damage near current levels. This is a regional estimate, not an India funding requirement.
Coastal Growth Is Concentrating Risk
More than 400 million people live within 10 kilometres of the sea across the economies studied, and those coastal areas generate an estimated $7 trillion in annual output. Ports, jobs and access to markets draw people and investment to the coast. But settlement has grown faster in flood-exposed areas than along the coast overall, placing more homes and infrastructure in harm’s way even before future sea-level rise is considered.
The burden differs across countries. India, China and Indonesia face some of the largest projected losses in dollar terms, while flood damage could take a far larger share of national income in small island states. A regional monetary total cannot capture both kinds of vulnerability equally.
India’s Exposure Is Also a Question of Who Can Adapt
India’s projected 21.5 million people affected annually by 2100 reflects the report’s high-emissions scenario. ADB also finds that, in India, flood-prone coastal communities tend to be poorer than communities elsewhere along the coast. Households facing greater exposure may therefore have fewer resources to protect their homes and livelihoods or recover after a flood.
The costs extend beyond buildings. The report’s assessment of coastal and ocean assets identifies mangrove loss as India’s largest source of welfare loss among the assets it examines. Mangroves provide protection and support fisheries and livelihoods—benefits that an estimate of damaged property alone can miss.
Protection Must Change as Conditions Change
ADB argues for adaptive coastal planning: deciding what to protect or improve now, while preparing to change course as sea levels, settlement patterns and local conditions evolve. Depending on the place, options range from flood barriers and better drainage to restored dunes and mangroves, raised infrastructure, or—as a difficult last resort—planned relocation.
That approach requires more than individual projects. Land-use decisions, public investment, ecosystem management and maintenance need to work together over decades. ADB’s review of past projects notes that shoreline plans in India lacked mandatory status for government agencies in one programme, illustrating why a technically sound plan may have limited effect without authority to guide decisions.
Policy Relevance
For India, the immediate planning issue is not only how to defend existing coastal settlements, but whether new housing and infrastructure continue to expand into areas expected to become more hazardous. Flood protection can reduce losses, yet it may also encourage further development behind a barrier unless land use and future risk are considered together.
The report also gives public investment a wider test. Projects protecting poorer communities, fisheries or mangroves may deliver substantial benefits that cannot be recovered through user charges. Choosing and financing coastal adaptation therefore requires attention to who is protected, not only the value of assets on a flood map.
Follow the Full Report Here: ADB, Asia–Pacific Climate Report 2026: Coastal Risks on the Rise—Actions for a Resilient Future