The ocean is rising faster now than at any point in recorded history, with impacts already being felt across developed and developing nations, according to a press release by United Nations (UN) published on 29 August 2026. Land is being inundated, homes are flooding, and livelihoods are being lost, driving significant hardships on people in search of a more secure future. Beyond the environment, rising sea levels are affecting human rights, economic development, health, culture, the future of many countries and basic human dignity. The ability to act and adapt today will prove decisive for whether rising seas become a manageable challenge or a generational crisis. The scale of the threat now touches everyone, everywhere.
Between 2014 and 2023, the global sea level rose 4.7mm a year, and in 2024 it jumped a record 5.9mm. Even under the most optimistic scenario, oceans will likely rise up to 0.55 metres by 2100, while under the worst case they could climb over a metre. A small but high-impact chance exists under high emission scenarios of nearly 2 metres by the end of the century. The drivers include melting glaciers and ice sheets and thermal expansion of warming oceans. About 91 per cent of the planet’s excess heat is being absorbed by the ocean, locking in future rises.
Around 770 million people, roughly 1 in 10 humans, live less than five metres above the high tide line. Freshwater wells and farmland are turning salty, while flooding is damaging hospitals, schools and sanitation systems. Increased exposure to waterborne disease threatens drinking water supplies and contributes to growing psychological stress. Fisheries and tourism, the backbone of many coastal economies, are being disrupted. Some projections suggest up to 1.2 billion people could be displaced globally by 2050.
Coastal infrastructure damage already exceeds $1.8 trillion, and without adaptation, annual global losses could hit $1.4 trillion. Small Island Developing States lost $153 billion to climate hazards between 1970 and 2020, while US home insurance premiums jumped by 33 per cent between 2020 and 2023 in disaster-risk areas. Ports handling more than 80 per cent of global trade are increasingly exposed to flooding and rising seas. Pacific nations face relative sea-level rise of more than twice the global average, and low-lying delta cities such as Dhaka, Mumbai and Kolkata put over 14 million people at risk. Coastal megacities including Miami, New York and Guangzhou face losses of trillions of dollars if infrastructure is damaged.
Not all rise can be stopped, as some is already locked in, but the extent of further increases depends on how quickly harmful emissions are cut. One flashpoint is Antarctica’s Thwaites Glacier, covering around 190,000 sq km, whose collapse alone could trigger a sudden, irreversible sea-level jump of over half a metre. Developing countries need an estimated $310–365 billion a year for adaptation, yet global adaptation finance was only about $26 billion in 2023. Adaptation measures include early warning systems, sea walls, mangroves, dune restoration and the managed retreat of people from threatened areas. Boosting adaptation finance and ensuring statehood is not affected by rising seas remain essential to protect people’s homes, histories, livelihoods and identities.