Global sea level rise and regional variability
On the basis of tide level data it is known that the sea level is rising since 1990 by almost 2 cm per decade on global average. Since the early 1990s, satellite measurements show a higher value of 3 cm per decade, such that the global sea level has risen by about 20 cm since 1900. On a regional scale, however, the impact of dynamic changes in the climate system on the sea level is often of greater importance. Through a synthesis of observed data with a dynamic ocean model it was attempted to reconstruct these changes for the last 60 years. The elastic deformation of the Earth and gravitational and rotational changes are not part of this reconstruction.
In particular, climate modes such as the North Atlantic Oscillation and El Niño affect regional patterns of sea level variability strongly as it is visible for the strong El Nino during 1997/98. The eastward shift of the warm water associated with the El Nino phase produces, for example, sea level changes of more than 20cm. The increase that takes place over the entire period thus remains almost unnoticed to the viewer.