Updated Sept. 17, 2018: An earlier version of this article did not account for border disputes between neighboring countries. 

Around the world, coastal communities may soon find themselves struggling to keep their heads above water. Data compiled by the World Bank shows the 37 countries that have lost the most land over the last half a century and, while some losses are more dramatic than others, nearly every coastal country in the world could see a loss at the turn of the century.

Between 1961 and 2017, the Caribbean island nation of St Kitts and Nevis lost more than a quarter of its land area – the most of any country in the world – partly due to rising sea levels. The dual-island country is relatively exposed geographically, making it more heavily impacted by extreme weather events like hurricanes and extreme storms, such as Hurricanes Luis (1995), Georges (1998), and Lenny (1999), which have battered the nation in recent years.

When these extreme weather events hit, winds push sand from the beach system and deposit it offshore onto large sandbars, causing the beaches to become narrower and lower in elevation, according to the US Geological Survey. Not only does this displacement impact economies that rely on expansive white sand beaches for tourism, but beach erosion also threatens coastal properties and infrastructures like roads and buildings. 

In all, St Kitts and Nevis lost about 90 square kilometers (35 square miles) of land. While some of this is due to sea level rise, a closer look at the data shows nearly all of the land loss occurred in a single year, 1980-81. In 1980, the UK allowed the island of Anguilla to secede from St Kitts and Nevis to become a separate colony. Three years later, St Kitts and Nevis became a separate state. Similarly, Ecuador and Peru have been in dispute over territorial boundaries for the better half of a century before settling it in 1990, an event that could explain the country losing more than 10 percent of its area or a total of nearly 28,500 square kilometers (11,000 square miles). Vietnam and Bulgaria, which have lost 4.74 percent and 1.87 percent of their land respectively, were closely followed by the island nations of the Seychelles and Cuba.

In 2014, sea level rise was 6.6 centimeters (2.6 inches) above the previous 1993 record average. Sea levels around the world are rising at an increasing rate, and the National Oceanic and Atmospheric Administration suggests they will continue to do so at even higher rates than we’re seeing now. This could breed trouble for 10 of the world’s largest cities, which are all found near the coast.

A major cause of this rise is the thermal expansion of water as it warms paired with more melting of land-based ice stores like glaciers and ice sheets.  

Between 2005 and 2016, sea levels have risen about 35 millimeters (1.4 inches) along the Eastern US, and with it comes more frequent flooding. Failing to curb sea-level rise could cost the world an estimated $14 trillion annually by 2100 if the 2°C (3.6°F) warming limit is missed.

[H/T: World Economic Forum]