Huge Dam in the North Sea Could Theoretically Protect Northern Europe From Sea Level Rise, Scientists Say

A vast dam structure across the entrances to the North Sea could—theoretically—protect more than 25 million Europeans against sea level rise as the planet warms, two scientists have said.

Sjoerd Groeskamp, from the Royal Netherlands Institute for Sea Research, and Joakim Kjellsson, at the GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, have described the idea in a paper accepted for publication in the Bulletin of the American Meteorological Society.

They were exploring the idea of a massive dam as a kind of thought experiment to highlight the potentials risks of sea level rise on the region. They stress it is a not a plan for an actual infrastructure project.

Nevertheless, Groeskamp and Kjellsson say the project is "technically feasible"—although there would be several significant challenges and drawbacks, an a potential price tag of up to $540 billion.

"It might be impossible to truly fathom the magnitude of the threat that global-mean sea level rise poses," the authors wrote in the study. "However, conceptualizing the scale of the solutions required to protect ourselves against global-mean sea level rise, aids in our ability to acknowledge and understand the threat that sea level rise poses. On these grounds, we here discuss a means to protect over 25 million people and important economical regions in northern Europe against sea level rise."

According to the researchers, the project might be the most viable solution to protect the region if climate change is left unchecked and sea levels rise by several feet over the next few centuries, as predicted by computer models.

They propose a nearly 400-mile-long Northern European Enclosure Dam (NEED), which would consist of two parts, disconnecting the North and Baltic seas from the Atlantic Ocean. The first section would be a 295 mile dam between the north of Scotland and the west of Norway, while the second is a 99-mile dam between the west point of France and the southwest of England.

"NEED may seem an overwhelming and unrealistic solution at first," the authors wrote. "However, our preliminary study suggests that NEED is potentially favorable financially, but also in scale, impacts and challenges compared to that of alternative solutions, such as (managed) migrations and that of country-by-country protection efforts."

The researchers say that the construction of the NEED dam would be a significant challenge. However, they argue that the construction may be "technically feasible," highlighting that substantial expertise exists with regards to to the engineering of enclosure dams.

The largest enclosure dams constructed to date are the Afsluitdijk in the Netherlands and the Saemangeum Seawall in South Korea, both measuring around 20 miles in length.

North Sea
Stock photo: An oil rig can be seen during a winter storm in the North Sea. iStock

"The maximum depth of the North Sea between France and England is scarcely 100 meters (328 feet)," Groeskamp said in a statement. "The average depth between Scotland and Norway is 127 meters (416 feet), with a maximum of 321 meters (1,053 feet) just off the coast of Norway. We are currently able to build fixed platforms in depths exceeding 500 meters (1,640 feet), so such a dam seems feasible too."

The researchers also estimate the potential cost of NEED, saying it will likely require between 250-500 billion euros (around $270-540 billion)—a figure based on extrapolating the costs of other large dams.

Groeskamp and Kjellsson argue this represents a good value for money compared to defensive infrastructure that the countries affected would otherwise have to construct. They say protection of coastal areas and cities where sea level rise exceeds 6.5 feet would "quickly become multi-billion euro investments." The combined expenditure from countries affected "far exceeds the costs of constructing NEED. For protection against long term sea level rise projection, NEED is almost certainly the least costly option."

But even though the researchers argue that NEED is both technically and financially feasible, they note that the project could have several negative consequences. For example, it would have a significant impact on the maritime industry, with Europe's busiest trading ports all sitting within the enclosure.

Nevertheless, they say solutions are available for these issues. For example, gates could be incorporated into the dam to allow shipping traffic through.

"Sluice gates allowing for some of the largest ships in the world are already operational in the Netherlands and Belgium," they wrote. "Alternatively harbours could be built on the ocean-side of NEED from where goods could be transferred to trains or to vessels operating within the enclosure."

They also note the maritime industry will likely be affected by sea level rise as and when ports are forced to relocate or be upgraded with protection measures.

Groeskamp and Kjellsson also acknowledge that NEED would dramatically alter the movement of silt and nutrients in the damned area. "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 said in a statement.

Northern European Enclosure Dam
A map showing the Northern European Enclosure Dam (NEED) proposed in the study. Sjoerd Groeskamp/​​​​Joakim Kjellsson

When evaluating the project as a whole, the researchers say that the impacts on the environment and maritime industry must be considered if the project were ever taken further.

That a proposal such as NEED could even be considered a viable option to protect citizens, highlights the severe risks of sea level rise, the duo say. While they do not come to a conclusion over whether the dam should or even could be built, they call for immediate solutions to reduce the impacts of climate change, in order to render such an idea unnecessary.

"Ultimately, the description of this extreme dam is more of a warning than a solution," Groeskamp said. "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 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."