Regional sea level changes in Norway : time series analysis of tide gauge data

Abstract

Changes in sea level impacts the life on earth. According to the fifth assesment report, published by the International Panel on Climate Change, the global sea level is rising and the sea level is an important indicator of climate change. Recent studies states an increase of about 20 cm in global mean sea level for the past century, and an acceleration of sea-level rise in the last decades.

On order to predict future sea level changes, analysis of past sea level is needed. This master thesis is a study of regional sea level changes in Norway. Time series analysis is used on tide gauge data to find both the total sea level changes and linear sea level trends in Norway.

The study discovered an increasing sea level for the included tide gauge stations in Norway. For example, has Oslo experienced a sea level increase of 1.17 +/- 0.39 mm per year, with a total sea level rise of 0.12 [0.08:0.15] meters from 1914 to 2012. Bergen has experienced a sea level increase of 1.40 +/- 0.33 mm per year, with a total sea level rise of 0.14 [0.10:0.17] meters from 1915 to 2012.

The linear trend in Norwegian sea level is partly increasing, depending on the station. In nine of thirteen stations, the linear slope from the time interval 1980-2012 is significantly larger than the linear slope for the time interval 1950-1980. It was detected a significant structural change in the linear slope in Bergen, Oslo and Stavanger before and after 1980, which indicates a change in sea level. Comparisons with global studies indicates partly correspondents with Norwegian and global results.