Several factors are apparently influencing the rate of sea-level rise across the world. Actual sea-level has risen about 400 feet since the peak of the last ice age almost 18,000 years ago. Most of the rise occurred between 12,000 and 18,000 years ago. In fact, scientists found that from 3,000 years ago to the start of the 19th century sea level was almost constant. Measurements since 1993 indicate a slight acceleration in rise of sea levels. The current rate is less than one-eighth of an inch per year.
It is very likely that 20th century warming has contributed significantly to the observed sea-level rise, especially through the widespread loss of land ice. Sea-level rise can be a product of global warming through the expansion of sea water as the oceans warm, and melting of ice over land. Several scientists indicate warming is predicted to cause significant rises in sea level over the course of the twenty-first century.