From Wikipedia "sea level rise"

Sea level rise is an increase in sea level. Multiple complex factors may influence such changes.

Sea level has risen around 130 metres (400 feet) since the peak of the last ice age about 18,000 years ago. Most of the rise occurred before 6,000 years ago. From 3,000 years ago to the start of the 19th century sea level was almost constant, rising at 0.1 to 0.2 mm/yr. Since 1900 the level has risen at 1 to 3 mm/yr;[1] since 1992 satellite altimetry from TOPEX/Poseidon indicates a rate of rise about 3 mm/yr.[2]

Sea level rise can be a product of global warming through two main processes: expansion of sea water as the oceans warm, and melting of ice over land. Global warming is predicted to cause significant rises in sea level over the course of the twenty-first century.