The Permanent Service for Mean Sea Level has been collecting data from all over the world and collating it at the National Oceanography Centre (NOC) in Liverpool, England, since 1933. They have now released their latest interactive world map allowing users to explore the changes in Earth’s sea level.
The Mean Sea Level Anomalies map demonstrates from year to year how sea level varies when compared with a long-term average calculated using data gathered between 1960 and 1990.
Moving the slider from one side to the other allows a user to see a variance of up to 20 centimetres at some locations.
There is a lot of data being used here, with many trends and notable exceptions to the data. For example, the land surrounding the Baltic Sea is uplifting as the earth recovers from the collapse of a large ice sheet that had covered the region during the last ice age and had subsequently pushed the earth down. Thus, sea level is apparently decreasing in that area, meaning that the anomalies in that region move from red to blue when you move the slider.
There is also a Relative Sea Level Trends explorer which allows you to ‘see how the estimate of a constant change in time (a trend) for each of tide gauge records depends upon the period of the data used in the calculation.’
Source: National Oceanography Centre
