Research carried out by Utrecht University, Deltares and TNO shows that between 8500 and 8300 years ago the sea level around the Netherlands rose by 2m per century. The scientists calculated the sea level at that time by dating the deep-lying submerged layers of peat in the Rotterdam area. The study, published in the scientific journal Geology this month, has important implications in light of the rapid rate of sea level rise expected in coming centuries.
“The rapid rate of sea level rise was primarily the result of the draining of large glacial lakes in North America, which caused the ice dams from the preceding ice age to gradually melt away,” explains researcher Marc Hijma from Utrecht University. “As a result, the sea level rose, the North Atlantic became less salty and the warm Gulf Stream was interrupted. This was followed by a cold period around 8200 years ago, which is known as the 8.2 event.”
8.2 event could occur again
This research is important because it reveals the volume of water which entered the North Atlantic with the draining of the glacial lakes. “Climate models will now be able to more effectively reproduce the 8.2 event, and it will be much easier to test the sensitivity of the warm Gulf Stream to an increased volume of freshwater. In the near future, there is a chance the North Atlantic could again become less salty due to the increased rate at which the Greenland ice cap is melting,” says Hijma. In theory, this could again interrupt the warm Gulf Stream or cause it to become less powerful, resulting in a very cold period, primarily in North-West Europe. In response to this theory, climate models are being implemented to determine whether this will in fact occur. The new results will increase the reliability of the scenario predictions.
The Netherlands submerged
The rapid rate of sea level rise left the Netherlands submerged in a fairly short period of time. Hijma explains: “Before 8500 years ago, the landscape around Rotterdam was still characterised by a river valley. However, 500 years later, this had completely changed and the entire area consisted largely of mud flats (comparable to the Wadden Sea area), through which the Rhine and Meuse rivers flowed.” Hijma’s doctoral thesis, which describes in detail the submersion of the western region of the Netherlands between 10000 and 6000 years ago, also supports these results. Hijma obtained his doctorate on 23 December 2009 at Utrecht University. His was the 500th doctoral qualification ceremony at Utrecht University that year, which proved to be a record year. Never before have so many doctoral qualifications been conferred at a Dutch university.
Publication
‘Timing and magnitude of the sea level jump preluding the 8200 yr event’, Geology, Marc Hijma and Kim Cohen.
Further information
Peter van der Wilt, Utrecht University press officer, +31 30 253 37 05, p.m.vanderwilt@uu.nl.