Researchers suggest major dams could protect against projected sea rises, with substantial consequences

14 February 2020

New research has suggested that two large dams could be a solution to protect more than 25 million Europeans against the consequences of an expected sea level rise of several metres over the next few centuries, while also stating that the design of such extreme dams is mainly a warning which ‘reveals the immensity of the problem hanging over our heads.’

Dr Sjoerd Groeskamp, oceanographer at the Royal Netherlands Institute for Sea Research, and Joakim Kjellson at GEOMAR in Kiel, Germany, published research this month in The Bulletin of the American Meterological Society that suggests building a 475km long dam between the north of Scotland and the west of Norway and another one of 160km between the west point of France and the southwest of England could act as a defence against climate change.

The research calculates that the costs to build the dams could be between €250-500 billion, which amounts to 0.1% of the gross national product, annualy over 20 years, of all the countries that would be protected by such a dam.

“The construction of such a ‘North-European Enclosure Dam’ seems to be technically feasible,” Groeskamp emphasised. “The maximum depth of the North Sea between France and England is scarcely one hundred metres. The average depth between Scotland and Norway is 127m, with a maximum of 321m just off the coast of Norway. We are currently able to build fixed platforms in depths exceeding 500m, so such a dam seems feasible too.”

The authors acknowledge that the consequences of this dam for North Sea wildlife would be considerable. ‘The tide would disappear in a large part of the North Sea, and with it the transport of silt and nutrients. The sea would eventually even become a freshwater lake. That will drastically change the ecosystem and therefore have an impact on the fishing industry as well’, Groeskamp elaborated.

“We estimated the financial costs for the construction of the dam by extrapolating the costs for large dams in South Korea, for example. In the final calculation, we must also take into account factors such as the loss of income from North Sea fishing, the increased costs for shipping across the North Sea and the costs of gigantic pumps to transport all of the river water that currently flows into the North Sea to the other side of the dam.”

Ultimately, the description of this extreme dam is more of a warning than a solution, Groeskamp stated. ‘The costs and the consequences of such a dam are huge indeed. However, we have calculated that the cost of doing nothing against sea level rise will ultimately be many times higher. This dam makes it almost tangible what the consequences of the sea level rise will be; a sea level rise of 10m by the year 2500 according to the bleakest scenarios. This dam is therefore mainly a call to do something about climate change now. If we do nothing, then this extreme dam might just be the only solution.”

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