Sea Levels Are Rising Faster Than Expected — Some Countries Could Disappear Underwater

Global sea levels are rising at a record pace: while the average annual increase between 2014 and 2023 was 4.7 millimeters, in 2024 it jumped to 5.9 millimeters. This is according to a special report by UN Secretary-General António Guterres, presented at the Pacific Islands Forum in Palau.

Under the most optimistic projection, sea levels will rise by 0.55 meters by 2100; under the worst-case scenario, by more than a meter. Under high-emission scenarios, a rise of nearly two meters by the end of the century cannot be ruled out, the UN document warns. Currently, around 770 million people — nearly 10% of the world's population — live in coastal areas less than five meters above high tide level.

Where the "extra" water comes from

Besides melting glaciers, about a third of the sea-level rise is due to thermal expansion of the ocean itself, which absorbs roughly 91% of the planet's excess heat. According to NASA, warming the upper 100 meters of the tropical ocean by 1°C adds about 3 centimeters to sea levels in that region.

Greenland loses an average of 266 billion tons of ice each year, while Antarctica loses about 135 billion tons over the same period. However, due to gravitational effects, melting Antarctic ice will raise sea levels along European coasts more than melting Greenland ice would. The fastest rise is happening in the western Pacific, where levels have climbed 10–15 centimeters since 1993 — nearly double the global average rate at the time.

"Coastal areas are already vulnerable to storms and waves. As sea levels rise, the frequency of such disasters increases. The problem starts long before the land actually goes underwater," explains Robert Nicholls, professor of coastal engineering at the University of Southampton.

States without territory

The fate of Pacific island nations is a particular cause for concern. For instance, Tuvalu — a country of around 10,000 people occupying just 26 km², whose highest point sits a mere 5 meters above sea level. The UN report treats the scenario of complete territorial loss as a real, not hypothetical, threat.

Under international law, territory is one of four essential attributes of statehood, alongside a permanent population, a government, and the capacity to enter into relations with other states. "No existing state has yet lost its territory due to natural conditions, so the legal questions surrounding its continued existence remain unresolved," says Michael Gerrard, an environmental law expert at Columbia University. In his view, the international community could establish a legal fiction allowing states to exist without territory.

Three years ago, Tuvalu signed a treaty with Australia under which its citizens will be able to obtain permanent residency there, and Canberra acknowledged that Tuvalu's statehood and sovereignty would persist even if the island is submerged. Last year, the International Court of Justice, in an advisory opinion, also came out in favor of preserving the statehood of already-existing countries.

The legal status of "climate refugees"

The legal status of people forced to leave their homeland due to rising waters remains unclear: the Refugee Convention does not recognize the concept of a "climate refugee," and the threat of climate change alone is usually not enough to qualify for refugee status. In 2019, however, the UN Human Rights Committee, in the case of Teitiota v. New Zealand, ruled that the principle of non-refoulement applies when climate change threatens the right to life.

Maritime borders pose a separate problem. Countries' exclusive economic zones extend up to 370 kilometers from shore and encompass rich fishing grounds and natural resources that are attracting growing interest from China, the United States, and other major powers. As coastlines recede, baselines shift and these zones shrink, threatening island nations with the loss of a significant part of their economies. As Sumudu Atapattu, professor of international law at the University of Wisconsin, notes, some Pacific nations are trying to "freeze" their maritime borders legally in order to retain resource rights even if their territory disappears — but exactly how this would work in practice remains unclear to everyone.

According to UN estimates, the value of at-risk infrastructure in wealthy coastal cities, including Miami, New York, and China's Guangzhou, ranges from $2 to $3.5 trillion. Yet the most vulnerable will be poorer regions of Asia and the Pacific, which have contributed the least to global warming — a situation experts describe as a form of climate injustice.

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Source: seznamzpravy.cz