Bering Strait Dam Proposal to Save AMOC Reignites Geoengineering Controversy

Could a dam across the strait that separates Russia from Alaska protect the Atlantic current that helps keep temperate areas liveable – or would such a closure hasten the current’s collapse? A new paper has set off the latest round in a century-long debate.

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With earlier options running out to halt global climate change, organizations around the world have turned to geoengineering projects that can artificially cool the Earth, thereby buying time for humans to get emissions under control. These projects include using sulfur particulates to recreate the natural cooling effect of volcanic eruptions; creating extra ice during the Arctic winter in order to reflect solar radiation away from the planet, and even launching a giant solar sail into space to act as a sunshade.

One ambitious proposal published in August by two scientists at Utrecht University suggests a solution to the weakening Atlantic Meridional Overturning Circulation, better known as the AMOC. They claimed that damming the Bering Strait – which separates the Pacific Ocean from the Arctic Ocean – could prevent the climate change-induced collapse of this vital oceanic system. 

But while the Utrecht scientists argue the dam would strengthen the AMOC, other modeling studies suggest a closed strait would instead accelerate its collapse and slow its recovery.

A previous analysis in 2012 from the National Center for Atmospheric Research in Boulder, Colorado, found that such a closure would “create conditions that are conducive to triggering abrupt climate transitions.” 

It is just the latest controversy on how the closure of the Bering Strait or other Arctic geoengineering projects might affect global ocean currents or the Arctic climate.

Over the past year, concerns have risen about the impact of global warming on the AMOC, often referred to as a “conveyer belt” that brings warm surface waters north and maintains Europe’s relatively mild climate, as well as carrying nutrients necessary to sustain ocean life. 

Already at its weakest in 1,600 years, a study released in August warned that AMOC is likely to become even weaker and shallower more quickly than previously predicted. The collapse of the AMOC would likely be irreversible, permanently impacting the climate in Europe in particular but also around the world. 

It may seem paradoxical that the Bering Strait, at the northern edge of the Pacific Ocean, could affect an Atlantic current. However, the delicate balance of the AMOC is strongly impacted by what happens in the Nordic Seas. There, the warmer, salty surface waters are cooled by the atmosphere and then sink and return southward. But this cooling is inhibited somewhat by relatively fresh North Pacific surface water that flows northward through the Bering Strait and ends up in the Labrador and Greenland Sea.

The proposal to dam the strait aims to halt the flow of relatively fresh Pacific surface water through the Bering Strait, which currently joins and weakens the AMOC. It claims that completely closing off the 80 kilometer (50 mile) Bering Strait with the construction of three linked dams is a technically feasible way to deter AMOC collapse.

The two scientists behind the proposal conducted paleoclimate and model simulations using an Earth system model that can simulate almost 10,000 model years per day. They showed that a closure of the Bering Strait leads to “a stronger AMOC with increased meridional heat transport … not only because it prevents fresh North Pacific waters from entering, but also because it reduces upper ocean water exchange between the Arctic and North Atlantic, which also reduces the input of fresh water into the North Atlantic.” 

According to the scientists, a Bering Strait dam would increase the AMOC strength slightly under present-day climate conditions. However, it would have to be done early enough – before the existing AMOC flow was reduced any more than 6.1%.

However, an earlier study, which reviewed research on ocean behavior from over 11,000 years ago when a land bridge naturally closed the strait, speculated the Bering Strait may have controlled the AMOC and affected the stability of the major Laurentide ice sheet.

The research team simulated scenarios under present-day conditions, examining two different circumstances: one with the strait closed and the other open, attempting to isolate its potential effects on the AMOC. They found that with the Bering Strait open, the AMOC would gradually slow as freshwater increased, remaining stagnant for around 400 years before recovering. However, with a closed Bering Strait, as freshwater strengthens in the North Atlantic, “the AMOC also weakens and part of the freshwater added to the North Atlantic is transported into the Arctic.” 

This would spark a chain of events that would ultimately result in the comparatively rapid collapse of the AMOC and an even slower recovery.

Plans to close the Bering Strait and geoengineer Atlantic ocean currents have existed since the 19th century – but for reasons opposite to today’s proposals. In 1887, a Harvard scientist proposed damming the strait on purpose to make the Arctic Ocean navigable. “If the vast low-lying districts of Eastern Siberia and Western Alaska were sunk beneath the sea, it would open wide the road of this vast ocean stream straightaway to the pole,” he wrote in The Atlantic.

An inventor theorized in 1912 that the Gulf Stream could be controlled by inducing deposits of sand on the Grand Banks by the Labrador Current, while in 1945 the head of UNESCO was so excited by the possibilities of nuclear weapons that he proposed exploding them at an appropriate height above the polar regions to raise the temperature of the Arctic Ocean and warm the entire climate of the northern temperate zones.

During the Cold War in the late 1950s, Petr Mikhailovich Borisov, a Soviet scientist, created a plan for the USSR to cooperate with the United States to dam the strait and pump 145,000 square kilometers of cold Arctic water into the Pacific. This, he argued, would draw warm Atlantic waters into the Arctic Basin and reduce the albedo of Earth as a result of the melting of the ice and snow, and would ultimately raise the temperature of the Arctic water by an amount in the range of 1.9-8.2C.

In 2024, the annual average temperature for the Arctic as a whole (all areas north of the Arctic Circle) was 1.11C above average, making it the third warmest year on record for the region. Over Arctic land, the temperature was 1.34C above average, making it the fourth warmest year, behind 2019.