Sea Level Rise

Many people assume that the sea level rise is low but in reality due to global warming a lot of land based glaciers are melting causeing the sea level to rise. Sea level rise hasn't had much of an increase since year until 1990, the level rise went from about 0 to 0.1. Carbon Dioxide is the main source of green house gas causing global warming making the Earth warmer as time passes.

This is a picture of the estimated amount of sea level rise in San Diego, this would take hundreds of years.
LINK

The ocean is not flat, although maps do make it seem that way but glaciers prevent oceans from being completely flat, the ocean stays in motion through gravity, wind, tides, and obviously glaciers. Scientists ahem different methods to measure specific things. For instance to measure the sea level rise they use satellite altimetry to accurately measure sea levels. 

This is a picture of land based ice glaciers melting increasing sea levels. LINK

 

In this this graph You can see the comparison between San Diego and Hawaii in the sea levels. This comparison goes from 1992-2006, for both locations. San Diego doesn't have much of an increase like Hawaii, makes sense because Hawaii is an island and San Diego isn't.