A paper that has been accepted for publication in the Bulletin of the American Meteorological Society has proposed an extraordinary measure to protect 25 million people and important economic regions of 15 Northern European countries from rising seas as a result of climate change: a mammoth Northern European Enclosure Dam (NEED) enclosing all of the North Sea.
“The concept of constructing NEED showcases the extent of protection efforts that are required if mitigation efforts fail to limit sea level rise,” the authors of the paper, Sjoerd Groeskamp of the Royal Netherlands Institute for Sea Research, and Joakim Kjellsson of the Helmholtz Centre for Ocean Research in Kiel, Germany, have written.
THE PROPOSAL: The scientists have proposed the construction of two dams of a combined length of 637 km — the first between northern Scotland and western Norway, measuring 476 km and with an average depth of 121 m and maximum depth of 321 m; the second between France and southwestern England, of length 161 km, and average depth of 85 m and maximum depth of 102 m.
According to Groeskamp and Kjellsson, separating the North and Baltic Seas from the Atlantic Ocean may be the “most viable option” to protect Northern Europe against unstoppable sea level rise (SLR).
They have also identified other regions in the world where such mega-enclosures could potentially be considered, including the Persian Gulf, the Mediterranean Sea, the Baltic Sea, the Irish Sea, and the Red Sea.
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THE RATIONALE: While NEED may appear to be “overwhelming” and “unrealistic”, it could be “potentially favourable” financially and in scale when compared with alternative solutions to fight SLR, the paper argues. The researchers classify the solutions to SLR into three categories of taking no action, protection, and managed retreat — and submit that NEED is in the second category.
While managed retreat, which includes options such as managed migrations, may be less expensive than protection (NEED), it involves intangible costs such as national and international political instability, psychological difficulties, and loss of culture and heritage for migrants. NEED, the paper says, will have the least direct impact on people’s daily lives, can be built at a “reasonable cost”, and has the largest potential to be implemented with the required urgency to be effective.
THE VIABILITY: Using the costs of building the 33.9-km Saemangeum Seawall in South Korea and the Maasvlakte 2 extension of the Rotterdam harbour in the Netherlands as examples, the researchers have estimated the total costs associated with NEED at between €250 billion and €550 billion. If construction is spread over a 20-year period, this will work out to an annual expense of around 0.07%-0.16% of the GDP of the 15 Northern European countries that will be involved. Construction costs would be higher for the UK, Denmark, Netherlands, Germany, and Belgium, amounting to roughly 0.15%-0.32% of their GDP annually for 20 years because of their vulnerability, awareness of SLR, or both.
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The construction will “heavily impact” marine and terrestrial ecosystems inside and outside the enclosure, will have social and cultural implications, and affect tourism and fisheries, the paper says.
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