Climate change raises sea level
Rising carbon dioxide and global temperatures are causing sea levels around the world to rise. This occurs for three reasons: (1) as water warms, it expands in volume (2) as global temperatures rise, ice sheets in the Arctic melt, releasing water into the ocean and (3) ice sheets in the Antarctic disconnect from the land and, like ice cubes in a glass of water, raise ocean levels when they enter the water.
If sea levels change slowly over time, barrier islands might simply move landward, as water washes over the island eroding its ocean side and depositing sediment on the sound side of the island. Rapid sea level rise, however, could inundate barrier islands and coastal areas, leaving them completely covered.