United Nations Secretary-General António Guterres warned Tuesday that sea level rise poses "unthinkable" risks to billions of people around the world, with dangerous implications for international peace and human rights.
Against that backdrop, he called for a coordinated and humane global response that includes investing boldly to slash both planet-heating emissions and the inequalities that exacerbate vulnerability, improving the adaptive capacity of frontline communities, and establishing legal frameworks to protect climate refugees.
"The impact of rising seas is already creating new sources of instability and conflict," said Guterres, who opened the U.N. Security Council's first-ever debate on the phenomenon's global consequences.
"Low-lying communities and entire countries could disappear forever," the U.N. chief warned. "We would witness a mass exodus of entire populations on a biblical scale. We would see ever-fiercer competition for fresh water, land, and other resources."
Describing the phenomenon as a deadly "threat multiplier," Guterres said that rising seas "jeopardize access to water, food, and healthcare."
"Saltwater intrusion can decimate jobs and entire economies in key industries like agriculture, fisheries, and tourism," he continued. "It can damage or destroy vital infrastructure—including transportation systems, hospitals, and schools, especially when combined with extreme weather events linked to the climate crisis."
"The impact of rising seas is already creating new sources of instability and conflict."
Citing new data from the World Meteorological Organization (WMO), Guterres noted that "global average sea levels have risen faster since 1900 than over any preceding century in the last 3,000 years," while oceans have "warmed faster over the past century than at any time in the past 11,000 years."
Glaciers and ice sheets are melting at an accelerated pace as greenhouse gas pollution, caused primarily by the burning of fossil fuels, continues to increase and heat up the planet. As Guterres pointed out, "We have already seen how Himalayan melts have worsened flooding in Pakistan."
"According to NASA, Antarctica is losing an average of 150 billion tons of ice mass annually," he continued. "The Greenland ice cap is melting even faster—losing 270 billion tons per year."
"Even if global heating is miraculously limited to 1.5°C, there will still be a sizeable sea level rise," said the U.N. chief. The WMO projects nearly one to two feet of sea level rise by 2100 even if the Paris agreement's more ambitious target is met, and 6.6 to 9.8 feet over the next 2,000 years.
"But every fraction of a degree counts," Guterres added. "If temperatures rise by 2°C, that level rise could double, with further temperature increases bringing exponential sea level increases."
The U.N. chief told the Security Council that "under any scenario, countries like Bangladesh, China, India, and the Netherlands are all at risk."
"Mega-cities on every continent will face serious impacts, including Lagos, Maputo, Bangkok, Dhaka, Jakarta, Mumbai, Shanghai, Copenhagen, London, Los Angeles, New York, Buenos Aires, and Santiago," Guterres continued.
"The danger is especially acute for nearly 900 million people who live in coastal zones at low elevations—that's one out of ten people on Earth," he added. "Some coastlines have already seen triple the average rate of sea level rise."
To "meet this rising tide of insecurity," Guterres called for "action across three areas."
First, he said, policymakers must adopt transformative policies immediately to mitigate the fossil fuel-driven climate emergency, "the root cause of rising seas."
"Our world is hurtling past the 1.5°C warming limit that a livable future requires, and with present policies, is careening towards 2.8°C—a death sentence for vulnerable countries," said the U.N. chief. "We urgently need more concerted action to reduce emissions and ensure climate justice."
"Developing countries must have the resources to adapt and build resilience against climate disaster," he continued. "Among other things, this meansdelivering on the loss and damage fund, making good on the $100 billion climate finance commitment to developing countries, doubling adaptation finance, and leveraging massive private financing at a reasonable cost."
Second, more attention must be paid to the preexisting injustices that intensify the impacts of sea level rise, said Guterres.
Policymakers should identify and address "a much wider range of factors that undermine security," including "poverty, discrimination and inequality, [and] violations of human rights," said the U.N. chief, who also called for improving early warning systems "to prepare and protect vulnerable communities."
"People's human rights do not disappear because their homes do."
Third, said Guterres, policymakers "must address the impacts of rising seas across legal and human rights frameworks."
"Rising sea levels are—literally—shrinking landmasses,a cause of possible disputes related to territorial integrity and maritime spaces," the U.N. chief explained. "The current legal regime must look to the future and address any gaps in existing frameworks."
"Yes, this means international refugee law," said Guterres. "But it also means innovative legal and practical solutions to address the impact of rising sea levels on forced human displacement and on the very existence of the land territory of some states."
"People's human rights do not disappear because their homes do," he added.
The U.N. Human Rights Committee ruled in 2020 that it is unlawful for governments to return refugees to countries where their lives are at risk due to catastrophic climate change.
Last year, the U.N.'s legal arm, the International Law Commission, "explored a range of potential solutions" to the problems posed by rising seas, including "continuing statehood despite loss of territory, ceding or assigning portions of territory to an affected state, or even establishing confederations of states," Guterres pointed out. "These discussions are critical to finding solutions."
As Inside Climate Newsreported, Tuesday's debate "was initiated by Malta, a small island nation strategically located between Africa and Europe in the central Mediterranean Sea. The island is a focal point for rescuing migrants from developing countries in the Global South, who are fleeing rising sea level and other climate impacts by trying to make dangerous boat crossings from Africa to Europe."
"The United Nations refugee agency, UNHCR, estimates that about 21.5 million people have been displaced on average each year since 2008 by extreme weather and other climate impacts," ICN noted. "The flow of refugees into Europe has triggered a social and political backlash that has strengthened right-wing authoritarian parties, which could undermine international cooperation on various global risks, including global warming."
Csaba Kőrösi, the current president of the U.N. General Assembly, also addressed the Security Council on Tuesday.
Lamenting estimates indicating sea level rise is likely to force between 250 and 400 million people from their homes by the end of the century, the Hungarian diplomat also warned that rising oceans imperil some of the world's most important "breadbaskets," including fertile deltas along the Nile, Mekong, and other rivers.
"What is needed now—as ever—is the political will to act," said Kőrösi.
Guterres, meanwhile, stressed that "we must keep working to protect affected populations and secure their essential human rights."
"The Security Council has a critical role to play in building the political will required to address the devastating security challenges arising from rising seas," the U.N. Chief concluded. "We must all work to continue turning up the volume on this critical issue, and supporting the lives, livelihoods, and communities of people living on the frontlines of this crisis."