How has the sea level in the Netherlands developed during the past nine thousand years?
Published: 5 June 2019
New standardised analysis of the ‘Greater Rotterdam’ sea level
Marc Hijma (Deltares) and Kim Cohen (Utrecht University) selected the most accurate geological sea-level observations for the southwest part of the delta, which they refer to in their publication as ‘Greater Rotterdam’. The observations consist of data relating to the depth and age of buried layers of peat.
Thin layers of peat formed around the water level associated with the sea level at that time. Rivers and tides were also factors. Using an internationally accepted method developed in part by Hijma, many of these data have now been re-analysed in a standardised way with an objective error analysis of the sea level and age for each point.
The database shows that the sea rose from -22 to -2 metres between 9000 and 3000 years ago. Initially, the rise was very fast: an average of one metre a century between 9 and 8 thousand years ago. The rate of rise then fell rapidly to approximately 0.1 m/century around 3000 years ago. By comparison: the level rose by just less than 0.2 m/century during the twentieth century.
Two-stage sea-level jump
The article also shows that there was a two-stage jump in the sea level lasting two centuries around 8450 years ago. That jump was caused by the emptying of huge ice lakes in Eastern Canada in combination with the accelerated melting of land ice in the same area. The rate of rise then peaked briefly at 2 metres a century.
Quaternary Science Reviews publication
The article and the database have been included in a special issue of the professional journal Quaternary Science Reviews, which publishes contributions from all over the world. The aim of the special issue is to establish a global database of sea-level index points going back 20,000 years. The geological data are used to calibrate linked sea-level/climate/ice-cap models. This allows for a more reliable analysis of modern sea-level measurements and sea-level rise scenarios for the future.
Hijma and Cohen’s paper can be downloaded and read free of charge using this link until 2 July.