Computer Simulations Show Nightmare Atlantic Current Shutdown Less Likely This Century

The sun rises over the Atlantic Ocean as a bird flies in Lido Beach, New York, US, February 26, 2025. (Reuters)
The sun rises over the Atlantic Ocean as a bird flies in Lido Beach, New York, US, February 26, 2025. (Reuters)
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Computer Simulations Show Nightmare Atlantic Current Shutdown Less Likely This Century

The sun rises over the Atlantic Ocean as a bird flies in Lido Beach, New York, US, February 26, 2025. (Reuters)
The sun rises over the Atlantic Ocean as a bird flies in Lido Beach, New York, US, February 26, 2025. (Reuters)

The nightmare scenario of Atlantic Ocean currents collapsing, with weather running amok and putting Europe in a deep freeze, looks unlikely this century, a new study concludes.

In recent years, studies have raised the alarm about the slowing and potential abrupt shutdown of the Atlantic end of the ocean conveyor belt system. It transports rising warm water north and sinking cool water south and is a key factor in global weather systems.

A possible climate change-triggered shutdown of what's called the Atlantic Meridional Overturning Circulation or AMOC could play havoc with global rain patterns, dramatically cool Europe while warming the rest of the world and goose sea levels on America's East Coast, scientists predict.

It's the scenario behind the 2004 fictionalized disaster movie “The Day After Tomorrow,” which portrays a world where climate change sparks massive storms, flooding and an ice age.

Scientists at the United Kingdom's Met Office and the University of Exeter used simulations from 34 different computer models of extreme climate change scenarios to see if the AMOC would collapse this century, according to a study in Wednesday's journal Nature. No simulation showed a total shutdown before 2100, said lead author Jonathan Baker, an oceanographer at the Met Office.

It could happen later, though, he said. The currents have collapsed in the distant past.

Still, the computer simulations should be “reassuring" to people, Baker said.

“But this is no greenlight for complacency,” Baker warned. “The AMOC is very likely to weaken this century and that brings its own major climate impacts.”

The Atlantic current flows because warm water cools as it reaches the Arctic, forming sea ice. That leaves salt behind, causing the remaining water to become more dense, sinking and pulled southward. But as climate change warms the world and more fresh water flows into the Arctic from the melting Greenland ice sheet, the Arctic engine behind the ocean conveyor belt slows down. Previous studies predict it stopping altogether with one of them saying it could happen within a few decades.

But Baker said the computer models and basic physics predict that a second motor kicks in along the Southern Ocean that surrounds Antarctica. The winds there pull the water back up to the surface, called upwelling, where it warms, Baker said. It's not as strong, but it will likely keep the current system alive, but weakened, through the year 2100, he said.

Baker's focus on the pulling up of water from the deep instead of just concentrating on the sinking is new and makes sense, providing a counterpoint to the studies saying collapse is imminent, said Oregon State University climate scientist Andreas Schmittner, who wasn't part of the research.

Those Southern Ocean winds pulling the deep water up act “like a powerful pump keeps the AMOC running even in the extreme climate change scenarios,” Baker said.

As the AMOC weakens, a weak Pacific version of it will likely develop to compensate a bit, the computer models predicted.

If the AMOC weakens but not fully collapses, many of the same impacts — including crop losses and changes in fish stock — likely will still happen, but not the big headline one of Europe going into a deep freeze, Baker said.

Scientists measure the AMOC strength in a unit called Sverdrups. The AMOC is now around 17 Sverdrups, down two from about 2004 with a trend of about 0.8 decline per decade, scientists said.

One of the debates in the scientific world is the definition of an AMOC shutdown. Baker uses zero, but other scientists who have been warning about the shutdown implications, use about 5 Sverdrups. Three of Baker's 34 computer models went below 5 Sverdrups, but not to zero.

That's why Levke Caesar and Stefan Rahmstorf, physicists at the Potsdam Institute for Climate Research and authors of an alarming 2018 study about potential shutdown, said this new work doesn't contradict theirs. It's more a matter of definitions.

“An AMOC collapse does not have to mean 0 (Sverdrups) overturning and even if you would want to follow that definition one has to say that such a strong AMOC weakening comes with a lot (of) impacts,” Caesar wrote in an email. “The models show a severe AMOC weakening that would come with severe consequences.”



Surging Travel in Europe Spikes Concerns over Tourism's Drawbacks

FILE - Demonstrators march in downtown Barcelona, Spain, Wednesday, June 19, 2024, as residents protest mass tourism. (AP Photo/Emilio Morenatti, File)
FILE - Demonstrators march in downtown Barcelona, Spain, Wednesday, June 19, 2024, as residents protest mass tourism. (AP Photo/Emilio Morenatti, File)
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Surging Travel in Europe Spikes Concerns over Tourism's Drawbacks

FILE - Demonstrators march in downtown Barcelona, Spain, Wednesday, June 19, 2024, as residents protest mass tourism. (AP Photo/Emilio Morenatti, File)
FILE - Demonstrators march in downtown Barcelona, Spain, Wednesday, June 19, 2024, as residents protest mass tourism. (AP Photo/Emilio Morenatti, File)

Suitcases rattle against cobblestones. Selfie-snappers jostle for the same shot. Ice cream shops are everywhere. Europe has been called the world’s museum, but its record numbers of visitors have also made it ground zero for concerns about overtourism.

Last year, 747 million international travelers visited the continent, far outnumbering any other region in the world, according to the UN's World Tourism Barometer. Southern and Western Europe welcomed more than 70% of them, The Associated Press reported.

As the growing tide of travelers strains housing, water and the most Instagrammable hotspots in the region, protests and measures to lessen the effects of overtourism have proliferated.

Here's a look at the issue in some of Europe's most visited destinations.

What’s causing overtourism Among factors driving the record numbers are cheap flights, social media, the ease of travel planning using artificial intelligence and what UN tourism officials call a strong economic outlook for many rich countries that send tourists despite some geopolitical and economic tensions.

Citizens of countries like the US, Japan, China and the UK generate the most international trips, especially to popular destinations, such as Barcelona in Spain and Venice in Italy. They swarm these places seasonally, creating uneven demand for housing and resources such as water.

Despite popular backlash against the crowds, some tourism officials believe they can be managed with the right infrastructure in place.

Italy's Tourism Minister Daniela Santanchè said she thinks tourism flows at crowded sites such Florence's Uffizi Galleries that house some of the world's most famous artworks could be better managed with AI, with tourists able to buy their tickets when they book their travel, even months in advance, to prevent surges.

She pushed back against the idea that Italy — which like all of its Southern European neighbors, welcomed more international visitors in 2024 than its entire population — has a problem with too many tourists, adding that most visits are within just 4% of the country's territory.

“It’s a phenomenon that can absolutely be managed,” Santanchè told The Associated Press in an interview in her office on Friday. "Tourism must be an opportunity, not a threat — even for local communities. That’s why we are focusing on organizing flows.”

Where overtourism is most intense Countries on the Mediterranean are at the forefront. Olympics-host France, the biggest international destination, last year received 100 million international visitors, while second-place Spain received almost 94 million — nearly double its own population.

Protests have erupted across Spain over the past two years. In Barcelona, the water gun has become a symbol of the city's anti-tourism movement after marching protests have spritzed unsuspecting tourists while carrying signs saying: “One more tourist, one less resident!”

The pressure on infrastructure has been particularly acute on Spain's Canary and Balearic Islands, which have a combined population of less than 5 million people. Each archipelago saw upwards of 15 million visitors last year.

Elsewhere in Europe, tourism overcrowding has vexed Italy's most popular sites including Venice, Rome, Capri and Verona, where Shakespeare's “Romeo and Juliet” was set. On the popular Amalfi Coast, ride-hailing app Uber offers private helicopter and boat rides in the summer to beat the crowds.

Greece, which saw nearly four times as many tourists as its own population last year, has struggled with the strain on water, housing and energy in the summer months, especially on popular islands such as Santorini, Mykonos and others.

The impact of overtourism In Spain, anti-tourism activists, academics, and the government say that overtourism is driving up housing costs in city centers and other popular locations due to the proliferation of short-term rentals that cater to visitors.

Others bemoan changes to the very character of city neighborhoods that drew tourists in the first place.

In Barcelona and elsewhere, activists and academics have said that neighborhoods popular with tourists have seen local shops replaced with souvenir vendors, international chains and trendy eateries.

On some of Greece's most-visited islands, tourism has overlapped with water scarcity as drought grips the Mediterranean country of 10.4 million.

In France, the Louvre, the world’s most-visited museum, shut down this week when its staff went on strike warning that the facility was crumbling beneath the weight of overtourism, stranding thousands of ticketed visitors lined up under the baking sun.

Angelos Varvarousis, a Barcelona- and Athens-based academic and urban planner who studies the industry, said overtourism risks imposing a “monoculture” on many of Europe's hotspots.

“It is combined with the gradual loss and displacement of other social and economic activities,” Varvarousis said.

What authorities are doing to cope Spain's government wants to tackle what officials call the country's biggest governance challenge: its housing crunch.

Last month, Spain's government ordered Airbnb to take down almost 66,000 properties it said had violated local rules — while Barcelona announced a plan last year to phase out all of the 10,000 apartments licensed in the city as short-term rentals by 2028. Officials said the measure was to safeguard the housing supply for full-time residents.

Elsewhere, authorities have tried to regulate tourist flows by cracking down on overnight stays or imposing fees for those visiting via cruises.

In Greece, starting July 1, a cruise tax will be levied on island visitors at 20 euros ($23) for popular destinations like Mykonos and 5 euros ($5.70) for less-visited islands like Samos.

The government has also encouraged visitors to seek quieter locations.
To alleviate water problems, water tankers from mainland Greece have helped parched islands, and the islands have also used desalination technology, which separates salts from ocean water to make it drinkable, to boost their drinking water.

Other measures have included staggered visiting hours at the Acropolis.
Meanwhile, Venice brought back an entry fee this year that was piloted last year on day-trippers who will have to pay between 5 and 10 euros (roughly $6 to $12) to enter the city during the peak season.