Final answer:
An individual living in a country surrounded by water on all sides would be residing on an island. Increases in sea levels could cause significant issues for such locations, potentially leading to large-scale displacement and economic disruption.
Step-by-step explanation:
Someone living in a country surrounded by water on all sides would be residing on an island nation or in a city-state. This geographic feature is known as an island, as it is land fully enclosed by water. Notably, when a piece of land is completely surrounded by land with no direct access to the ocean, it is called a landlocked country. However, this is not the case for an island. If the sea levels were to rise significantly, as mentioned in the provided information, countries that are islands or coastal cities could face severe issues due to inundation. This would lead to the displacement of people and significant economic damage, especially since many populated cities are located in low-lying coastal areas vulnerable to such changes.