Climatologists discuss the possibility of damming the Bering Strait. Why?

Bering Strait with a visualization of the possible dam placement. Photo: Wikimedia Commons

Today, climatologists' attention is focused on the Atlantic Meridional Overturning Circulation (AMOC), which is one of the Earth's key climate systems. AMOC works like a giant water heating system: it transports warm water from the tropics across the Atlantic to the coasts of Europe. It is thanks to this system that the climate in many parts of Western and Northern Europe is significantly milder than it would otherwise be at such latitudes.

The AMOC mechanism is based on the difference in water temperature and salinity. Warm surface water moves north, gradually cools, some of it evaporates, and some freezes as sea ice. At the same time, salt remains in the water, making it denser and heavier. Near Greenland, such water sinks into the ocean depths and returns south as a cold deep-sea current.

But now this system is weakening. Scientists link this primarily to global warming and the influx of large amounts of fresh water into the North Atlantic — including through the melting of ice in the Arctic and Greenland. Fresh water lowers salinity, which means it hinders the sinking of cold masses into the deep. If this process continues, AMOC could reach a critical point and drastically weaken or even collapse.

For Europe, this threatens serious consequences. Despite global warming, the northern and western regions of the continent could face sharp cooling, harsher winters, and powerful storms. Some researchers call a potential AMOC collapse one of the greatest threats to humanity, on par with nuclear war.

Павялічыць

Atlantic Meridional Overturning Circulation. Photo: oceanservice.noaa.gov

Lessons from the Past and a Model for the Future

As writes Süddeutsche Zeitung, Dutch scientists are now seriously discussing an idea whose implementation, in their opinion, could save AMOC. It did not emerge from nowhere — scientists found a clue in Earth's history. Three million years ago, during the Middle Pliocene epoch, atmospheric CO₂ levels were close to modern levels, and temperatures were slightly higher.

However, there are also significant differences. Researcher Juliane Weiffenbach from Utrecht University found that at that time, AMOC was much stronger, and the reason for this was tectonic shifts that closed the Bering Strait. As a result, a land bridge formed between Asia and North America, and the Pacific Ocean was isolated from the north.

This inspired her colleague Jelle Soons with a bold idea: if nature did it once, humans can repeat it today. Together with Professor Henk Dijkstra, they conducted computer modeling to test how artificially closing the strait between Asia and North America would affect Atlantic currents.

The results, published in the scientific journal Science Advances, confirmed the hypothesis: if a dam 80 kilometers long and about 50 meters deep were built, it would stop the flow of fresh water from the Pacific Ocean into the Arctic. This would lead to an increase in salinity in the North Atlantic, which would 'restart' the water sinking mechanism and restore AMOC's former strength.

But it all depends on timing: if the right moment is missed, closing the strait could even worsen the situation. If too much fresh water has already accumulated in the surface layers of the North Atlantic, it will not be able to flow back into the Pacific Ocean due to the barrier. Furthermore, meltwater from Arctic ice would flow even more actively into the North Atlantic after such an intervention. To prevent an AMOC collapse, the closure must occur prematurely. More complex models should indicate precisely where this threshold lies.

Scientists even described how such a structure might look: two islands in the middle would serve as supports, between which three separate dams could be erected. This would be the largest dam in the world, but its scale is comparable to already existing structures. For example, in 2006, South Korea completed the Saemangeum Seawall, which is almost 34 kilometers long and up to 54 meters deep.

Between Risk and Last Chance

Despite the optimistic simulation results, the scientific community views the idea with a significant degree of skepticism. Marine physicists warn that ocean circulation is far more complex than any mathematical model.

Furthermore, closing the Bering Strait could give AMOC a reprieve, but it would not stop other climate consequences, such as the melting of Greenland's ice, which also alters weather conditions in Europe. Moreover, an intervention of such scale would inevitably disrupt marine animal migration routes and destroy important shipping lanes.

Soons and Dijkstra themselves emphasize: the main way to stabilize AMOC remains the rapid reduction of greenhouse gas emissions. They view the dam idea only as a last-resort scenario — in case all other measures fail and the system's collapse becomes inevitable. Soons compares it to gastric bypass surgery: it's best not to do it due to the risk of complications, but if it's the only way out, the option should be considered.

Today, scientists are working on more complex and detailed models to accurately determine whether such interventions make sense and what their nature might be. Latest generation climate models are capable of analyzing ocean processes more precisely and realistically reflecting the state of AMOC.

• 2
• 1
• 0
• 2
• 5
• 0
• 0
• 0