Quirks & Quarks

Is damming the entire North Sea a realistic way to defend against sea level rise?

It might be possible to build two giant dams to isolate much of Europe from the rising Atlantic, and it might be the only defence if we don't act fast to control climate change

More than you might think, but probably not as good as limiting climate change

The Northern European Enclosure Dam map shows the two proposed giant dams across the North Sea (Sjoerd Groeskamp)
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As the saying goes 'drastic times call for drastic measures'. The drastic projections for sea level rise in the next decades and centuries suggested a drastic measure to a Dutch researcher. 

Sjoerd Groeskamp, an oceanographer at the Royal Netherlands Institute for Sea Research, has proposed one potential way for much of Western Europe to defend itself against sea level rise. In a new paper he's proposed the possibility of the largest damming project in the world: Twin titanic dams that would isolate much of Europe's coastline from the rising Atlantic.

Groeskamp is clear that he doesn't think this is a desirable option. In fact, he admits that part of his reason for exploring this radical idea is to highlight the need for more conventional action on the climate change that is driving sea level rise. 

One dam would extend 475 kilometres from the north of Scotland to the west of Norway. The second would cross from the southwest of England to the west of France. Their proposed name comes with a message. It is called the Northern European Enclosure Dam, or NEED.

We have the technology

According to Groeskamp the construction of such dams is technically feasible. The average depth of the North Sea between Scotland and Norway is about 127 metres, while it's a little shallower in the channel the southern dam would cross. These are depths that the engineers he consulted suggest can be practically filled 

Groeskamp estimates the dams would cost between 250 and 500 billion Euros and take 50 to 100 years to complete. However he has also estimated that the massive cost is only 0.1 per cent of the gross national product over 20 years of the 15 countries negatively impacted economically by rising levels of the North Sea in the future.  

The future North Sea would be a freshwater lake

With these extreme dams in place, there would be consequences for the North Sea. In about 100 years according to Groeskamp, it would become a freshwater lake. Tides would disappear and river water would have to be pumped to the other side of the dam.

Saltwater ecosystems would collapse, and the North Sea fishing industry would follow close behind. Both would be replaced by something very different.

Harbours would have to be constructed outside the dams to replace the ones made redundant by the rising sea levels.

These catastrophic ecological changes would be just part of the cost of sea level rise. Groeskamp suggests this bleak scenario is possible, but that it would be much more desirable to take action on climate change and prevent it being necessary.

Written and produced by Mark Crawley