A new UN special report warns that accelerating sea-level rise is becoming a profound human-rights crisis, threatening housing, water, food, health, education and cultural identity for coastal communities.
With 770 million people living less than five metres above high tide and up to 1.2 billion at risk of displacement by 2050, it calls for urgent adaptation, finance and rights-based climate action.
Sea-level rise poses a serious threat not only to economies and physical infrastructure but also to cultural heritage, human rights and the identity of communities, according to a new United Nations report.
The United Nations Secretary-General’s Special Report, Challenges related to sea-level rise and ways and approaches to address it, was presented on August 31 by UN Deputy Secretary-General Amina J. Mohammed during the 55th Pacific Islands Forum Leaders Meeting in Palau.
The report notes that rising ocean levels, driven primarily by warming waters and melting glaciers and ice sheets, are already affecting communities worldwide. In 2024, the annual increase in global sea level reached 5.9 millimetres, the highest level ever recorded.
Today, around 770 million people or approximately 10 per cent of the world’s population, live in coastal areas less than five metres above the high-tide line and are already exposed to significant risks.
According to the report, sea level rise is already damaging urban infrastructure, water systems, transport networks, energy grids, buildings and groundwater resources, threatening human rights, development and financial stability.
It noted that the impacts vary across regions.
In high-income cities such as Miami and New York in the United States and Guangzhou in China, for example, the primary impact is the staggering financial exposure of coastal infrastructure, with assets at risk estimated between $2 trillion and $3.5 trillion.
In the low-lying deltas of South Asia, however, the crisis is increasingly defined by human displacement, with more than 14 million people in Kolkata, Mumbai and Dhaka at immediate risk of losing their homes to permanent inundation.
Sea-level rise threatens fundamental rights, including access to adequate housing, safe drinking water, sanitation, food, healthcare and education. Flooding and erosion can destroy homes, schools, hospitals and agricultural land, while saltwater intrusion contaminates freshwater supplies and soils. Damage to sanitation systems also increases exposure to water-borne diseases and other health risks.
Small Island Developing States (SIDS), Indigenous Peoples and low-lying coastal communities are particularly vulnerable.
Indigenous Peoples face particularly severe consequences as the loss of ancestral lands can disrupt cultural identity, spiritual connections and the transmission of traditional knowledge between generations. Displacement caused by rising seas may therefore become not merely an economic problem but a profound human-rights challenge.
The economic costs are equally alarming. Damage to coastal infrastructure is currently estimated at more than $1.8 trillion, and annual global losses could reach between $1.2 trillion and $4 trillion by the end of the century if adaptation measures are not implemented.
Rising seas also raise complex questions concerning statehood, sovereignty, nationality and maritime boundaries, particularly for island nations facing permanent territorial loss.
Effective adaptation requires early action, reliable scientific assessments, early-warning systems and resilient infrastructure.
The United Nations warns that without urgent adaptation measures, up to 1.2 billion people could be displaced by 2050.
Addressing these challenges requires both climate mitigation and adaptation. The report calls for stronger international cooperation, faster reductions in greenhouse-gas emissions, improved early-warning systems, greater climate-adaptation finance, better scientific information and stronger support for vulnerable communities.
However, developing countries face a major financing gap. Their annual adaptation needs are estimated at $310-$365 billion, compared with only $26 billion in adaptation finance in 2023.
Protecting communities will require stronger international cooperation, equitable and predictable financing, technology transfer and people-centred planning. A human-rights-based approach must place vulnerable communities at the centre of climate action, ensuring that rising seas do not become a crisis of lost homes, livelihoods, culture and fundamental rights.
Legal frameworks must also protect statehood, maritime zones and fundamental rights, ensuring dignity and stability for present and future generations.