Computer simulations show collapse of vital Atlantic current that warms Europe unlikely this century

The feared scenario in which Atlantic Ocean currents collapse, leading to chaotic weather and a severe cold snap in Europe, is unlikely to occur this century, according to a new study.

Research in recent years has highlighted concerns about the gradual deceleration and possible sudden cessation of the Atlantic end of the ocean's conveyor belt system.

It conveys warm water upwards and cool water downwards and plays a crucial role in global climate patterns.

Dramatically cool Europe while warming the rest of the world and raising sea levels on America's East Coast, scientists predict.

The scenario depicted in the 2004 film "The Day After Tomorrow" features a world where climate change triggers massive storms, flooding, and an ice age.

Researchers claim this should be a 'reassuring' discovery

Researchers at the United Kingdom's Meteorological Office and the University of Exeter employed simulations from 34 distinct computer models depicting extreme climate change scenarios to determine if the AMOC would cease functioning this century, as reported in a study published in this week's journal Nature.

According to lead author Jonathan Baker, an oceanographer at the Met Office, no simulation indicated a complete shutdown before the year 2100.

It's possible it could occur in the future, he said. The ocean currents have ceased to exist in the distant past. Nevertheless, the computer simulations should provide comfort to the public, Baker stated.

But this is no sign of a free pass," Baker cautioned. "The AMOC is very likely to decline this century and that will bring its own significant climate consequences.

What changes is global warming bringing to the Atlantic current?

The Atlantic current flows because as warm water reaches the Arctic, it cools and forms sea ice, leaving behind salt. This results in the remaining water becoming denser, sinking and being pulled southward.

The Arctic ice sheet, which plays a crucial role in the ocean's conveyor belt, is slowing down. Past research has forecasted that it could potentially stop entirely, with some predictions suggesting this could occur within a few decades.

Baker stated that computer models and fundamental physics suggest that a secondary motor activates in the Southern Ocean encircling Antarctica.

The winds in that area pull the water back up to the surface, known as upwelling, where it warms, Baker stated. It's not as powerful, but it will probably sustain the current system, albeit weakened, through the year 2100, he stated.

According to Oregon State University climate scientist Andreas Schmittner, who was not involved in the study.

Southern Ocean winds pushing deep water upwards act "like a powerful pump that keeps the AMOC running, even in extreme climate change scenarios," Baker stated.

As the Atlantic Meridional Overturning Circulation (AMOC) weakens, a weaker Pacific counterpart is likely to emerge to partially offset the effects, according to computer models.

What constitutes an AMOC shutdown?

It is still possible that this will occur, but not on a massive scale, Baker stated.

Scientists measure the Atlantic Meridional Overturning Circulation (AMOC) strength in a unit called Sverdrups. The AMOC is currently around 17 Sverdrups, down two from around 2004, with a trend of approximately 0.8 decline per decade, according to scientists.

One of the debates in the scientific community is the definition of an AMOC shutdown. Baker uses zero, but other scientists who have cautioned about the shutdown implications, use approximately 5 Sverdrups. Three of Baker's 34 computer models fell 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 a concerning 2018 study on the potential shutdown, stated that this new work does not contradict theirs. It's actually a matter of terminology.

“An AMOC collapse doesn't have to mean zero (Sverdrups) overturning, and even if you strictly follow that definition, one must acknowledge that a significant AMOC weakening comes with a multitude of impacts,” the researcher wrote in an email.

The models indicate a significant decline in the Atlantic Meridional Overturning Circulation, which would lead to severe repercussions.