In short, yes. According to many recent studies, average sea level has risen about 6 inches over the past 100 years. Thus estimate--although alarming--is an approximation. Due to the differences in geography and the land surface, calculating a global average for changes in sea level is a complicated process.

There are basically two ways that sea level can change: 1) the level of the ocean’s surface can change, and 2) the level of the land surface can change. Changes in the level of the ocean’s surface is usually a global scale change, such as melting of glaciers and polar ice caps that contribute to the actual volume of water in the ocean. Land surface changes, on the other hand, are usually observed on a local or regional scale.

Vertical movement of the land surface can occur due to tectonic effects, sedimentation, extraction of ground water and oil, or isostatic adjustment. This latter term refers to local or regional elevation changes that occur when a large load is relieved from the land surface. For example, due to the retreat of the last ice-age, melting glaciers relieved large amounts of stress (pressure) on the continents and caused various regions around the world to rise. This effect, which is called glacial rebound, cause the sea level in a particular region to lower. Because regional and global processes can either amplify or counteract one another we refer to sea level change at any given location as Relative Sea Level (RSL).