Enviro News Asia, New York — Rising sea levels are increasingly threatening coastal communities, livelihoods, infrastructure, and human rights worldwide, with the United Nations warning that the scale of future impacts will depend heavily on how quickly countries reduce emissions and strengthen climate adaptation.
The global sea level is rising faster than at any point in recorded history, according to the United Nations. Between 2014 and 2023, the average global sea level rose by 4.7 millimeters per year, while the rate reached a record 5.9 millimeters in 2024.
Even under the most optimistic emissions scenario, global sea levels could rise by up to 0.55 meters by 2100. Under higher-emission scenarios, the increase could exceed one meter, while a high-impact possibility of nearly two meters by the end of the century cannot be ruled out.
The rise is primarily driven by human-induced climate change. Melting glaciers and ice sheets contribute additional water to the oceans, while warming seawater expands and raises sea levels.
The ocean also absorbs around 91 percent of the excess heat generated by the climate system, meaning continued global warming will lock in further sea-level rise.
The consequences are already being experienced by coastal populations. Around 770 million people, or roughly one in 10 people worldwide, live less than five meters above the high-tide line, leaving many communities particularly exposed to flooding and coastal hazards.
Saltwater intrusion is contaminating freshwater supplies and farmland, while flooding is damaging hospitals, schools, sanitation infrastructure, and other essential services.
Coastal communities are also facing greater risks to drinking water and public health, including increased exposure to waterborne diseases. Fisheries and tourism, which provide livelihoods and support economies in many coastal regions, are also increasingly vulnerable.
The UN has warned that climate-driven displacement could reach as many as 1.2 billion people globally by 2050 under some projections, as communities seek safer places to live and opportunities to rebuild their livelihoods.
The consequences extend beyond physical and economic losses. Rising seas can threaten cultural heritage, ancestral lands, traditional ways of life, and community identities, creating significant social and psychological impacts.
The economic costs are also escalating. Coastal infrastructure damage already exceeds an estimated $1.8 trillion, while annual global losses could reach $1.4 trillion without adequate adaptation measures.
Small Island Developing States alone lost an estimated $153 billion to climate-related hazards between 1970 and 2020. Rising disaster risks have also contributed to higher insurance costs in vulnerable areas.
Global trade faces additional exposure because ports handling more than 80 percent of international trade are increasingly vulnerable to flooding and sea-level rise, creating potential disruptions across supply chains.
Small island nations and low-lying coastal regions face some of the greatest risks despite contributing relatively little to the greenhouse gas emissions driving climate change.
Several Pacific island countries are experiencing relative sea-level rise at more than twice the global average and face increasingly frequent flooding. Major low-lying cities and delta regions, including Dhaka, Mumbai, and Kolkata, are also highly exposed.
Coastal megacities such as Miami, New York, and Guangzhou face potentially enormous economic losses if critical infrastructure is damaged by flooding and rising seas.
The United Nations said sea-level rise cannot be completely stopped because some additional rise is already locked in by past emissions. However, the amount of further rise and the scale of resulting damage will depend on future emissions reductions.
Antarctica remains a major concern. The Thwaites Glacier in West Antarctica, which covers approximately 190,000 square kilometers, is closely monitored because its potential collapse could contribute to a substantial and potentially irreversible increase in global sea levels.
Reducing dependence on climate-warming fossil fuels remains the most important long-term measure for limiting further global warming and sea-level rise. At the same time, governments and communities need to accelerate adaptation measures.
These include early-warning systems, coastal protection infrastructure, mangrove restoration, dune rehabilitation, improved monitoring, and managed retreat from areas facing unavoidable risks.
Better legal and policy frameworks are also needed to address complex consequences, including questions surrounding statehood and maritime boundaries if parts of countries become permanently submerged.
The UN estimates that developing countries require between $310 billion and $365 billion annually for climate adaptation. However, global adaptation finance stood at only around $26 billion in 2023, highlighting a substantial gap between needs and available resources.
A UN report presented ahead of a high-level UN meeting on sea-level rise warned that rising seas represent one of the most profound threats facing populations worldwide.
The report examines the social, economic, and legal consequences of sea-level rise and outlines potential responses as countries prepare for the September 24 UN high-level meeting on the issue.
Navid Hanif, head of the UN Department of Economic and Social Affairs, stressed the need for a stronger collective response, emphasizing that global resilience, financing, and ambition must increase faster than the rising seas.
The UN said the future impacts of sea-level rise are not predetermined. The scale of losses will depend on decisions made today to cut emissions, finance adaptation, protect vulnerable communities, and safeguard the homes, livelihoods, cultures, and identities of people living along the world’s increasingly threatened coastlines. (*)
