The worst scenario in the face of a collapse of the Atlantic current: advance of the ice, drought and a slowdown in global warming

A few days ago the alarms went off: the Atlantic Circular Current (AMOC) could collapse. A study carried out by researchers from the University of Copenhagen and published in the journal Nature assured that this meteorological phenomenon could occur between 2025 and 2095, focusing on the year 2057.. The last time this happened on Earth was 150,000 years ago and we have heard its name more than once, especially thanks to the cinema: the Ice Age or last ice age.. But why does this occur? What does it mean when the Atlantic current collapses? What consequences could I produce on the planet? And in Spain? Is this phenomenon likely to occur in this century?

“This scientific article is one of the many that try to analyze ocean currents, something very important and that is certainly a great unknown of our climate system,” says Rubén del Campo, spokesman for the State Meteorological Agency, Aemet. “This work goes to say that they have detected some signs that the Atlantic current is slowing down and that it could even collapse.. Although they put it at 2057, they give a wide range,” he explains, adding that “there are other experts who disagree and it must be said that the Intergovernmental Panel on Climate Change (IPCC) considers that it is very unlikely that this collapse will occur in the century XXI”.

For his part, the professor of Physical Geography at the University of Barcelona, Javier Martín-Vide, endorses the theory of the Danish scientists. “The fact that the current of the oceans was interrupted was already talked about more than fifteen years ago, in 2007, and then it cooled down a bit.. It is very probable that this will happen on the dates indicated in the study”, he says, also emphasizing that “Nature magazine is the most important scientifically and what they publish goes through important filters”. The expert also assures that “from a physical point of view it is coherent and consistent”.

But what is an Atlantic Circular Current (AMOC) collapse? Del Campo explains it in a simplified way, although he emphasizes that it is a “very complex phenomenon”: “There is an ocean current in the Atlantic that transports warm waters from low latitudes to high latitudes. In the North Atlantic this superficial circulation sinks because there is a greater density (salinity and temperature) of the waters and it returns through the depths to the south”. Del Campo also adds that “due to factors such as the loss of ice by frozen masses such as Greenland, fresh water is added to the circulation and then the sinking of cold waters is not as effective and slows down, which can have consequences on the climate that translate into less heat transport from south to north”.

Because of this, the slowing of the current could lead to “abrupt climate change in Europe”. Thus, ice advances would occur in areas located further north, such as Iceland or northern Scandinavia and “global warming would be slowed down on the continent.”

In this sense, Martín-Vide gives a very clear example that makes us understand how the AMOC works and what would happen with its possible collapse.. “If we compare the New York winter with that of Lisbon or Porto, the cities are at the same sea level, bathed by the same ocean, almost on the same parallel and at the same latitude,” he explains, and continues: “In New York, winter It is harsh, there is snowfall every year, while in Lisbon there is hardly any snow and frost is very rare.This is because our Atlantic coasts are bathed by a branch of the Gulf Stream that is part of the Atlantic and is warm. In the United States the Labrador current, which is cold, goes down.”

The professor also assures that in the event of this disruption, “there would be a paradox that, given global warming, we would have a hiatus of a few years. Winters would be colder in this western part of Europe until this circuit, which affects the entire planet, is reconstituted,” he points out.. “The bottom line is that the behavior of the weather has a lot to do with the ocean, the weather as a whole, and the atmosphere.”

In this sense, Del Campo adds that another of the consequences would be that “rainfall patterns would vary clearly and Western Europe and Spain would become drier areas, where rainfall would be less. In Spain, perhaps there could also be more winters cold, but there are many uncertainties,” he asserts.

The smallest extent of ice in history

In short, the main cause of this future collapse is climate change, since it is this that causes the melting of the ice masses on the planet.. This is what in scientific language is known as a Heinrich event: events or episodes that occurred during the period of the last ice age (Wisconsin) and in which waves of icebergs broke off the glaciers and crossed the North Atlantic. Icebergs carried bulk rocks eroded by glaciers and when they melted offshore, they fell to the bottom as drifting debris.

According to Del Campo, the melting of frozen masses is a feasible event, especially in Greenland and the Arctic. “At the beginning of the 80s, in the Arctic there were seven million square kilometers covered by ice, now this extension is around 4 and a half million. There has been a significant decline of around 13% per decade,” says. “That in summer, but in winter it is also observed that in about 18 years there has been an ice loss of 16%.”

In addition, the Greenland glaciers are melting “6 or 7 times faster than 25 or 30 years ago”, something much more problematic than the melting of the Arctic “because it does raise sea levels”.. In addition, in Antarctica, where according to the expert “there is more uncertainty”, it has been possible to verify that “winter is being (there it is the cold season now) with less ice extension since there are records”. In Del Campo's words, this “is a very unusual situation.”

The worst case scenario

And although many scientists reiterate that the Atlantic event will not occur in the coming decades, the worst possible scenario in the face of climate change and the collapse of currents would be devastating for some areas of the planet. “Massive melting of the ice sheets in Greenland and Antarctica could occur with catastrophic consequences. Total stoppage of the current would change the climate, but massive melting could lead to catastrophic sea level rise in densely populated coastal cities.”