Miami also faces a unique problem. Highly porous limestone rocks allow seawater to seep into the ground, bypassing barriers and dams. Rising sea levels have already led to flooding during high tides. In Mexico City, the problem comes not from the sea but from subsidence. Massive groundwater extraction is causing the ground to sink by an estimated 20 to 30 centimeters per year in some areas, damaging the roads and infrastructure of a city of about 21 million people.
Alexandria in Egypt is threatened by rising sea levels and coastal erosion. The intrusion of saltwater into the Nile Delta could cause major damage to agriculture and the city’s rich historical heritage.
In Bangkok, many areas are about two meters below sea level. The city, built on soft soil in the Chao Phraya River delta, faces the risk of more frequent flooding, also affected by more intense rainfall. Jakarta is another worrying case. The city has sunk more than four meters in several decades and about 40% of the urban area is now below sea level. Because of this problem, Indonesia has begun construction of a new capital, Nusantara, on the island of Borneo.
In Manila, Philippines, the land is sinking in some areas by about two centimeters per year, while sea levels continue to rise. The combination of these two factors makes the capital particularly vulnerable to flooding. Ho Chi Minh City in Vietnam also faces a major risk. About 40-45% of the urban area is less than one meter above sea level. In addition to rising sea levels, groundwater extraction is also causing land subsidence.
Venice, Italy, remains one of the most notorious cities for its flood risk. The city sits just above sea level and is struggling with both slow land subsidence and rising sea levels. The MOSE barrier system has reduced the risk of major flooding, but experts say more measures will be needed in the future.
In Amsterdam, water protection is much more advanced, with dams, pumps and barriers that have made the Netherlands a world example. However, this city also faces a growing risk. According to Dutch forecasts, by 2100 sea levels could rise by more than a meter in some coastal areas, requiring further changes to the protection systems.
The report emphasizes that these cities are examples of what could happen in many areas of the world if climate change and the factors that accelerate land subsidence are not addressed with concrete and urgent measures.