According to recent estimates, the giant water circulation in the Atlantic Ocean could stop within 300 years if the concentration of CO₂ in the atmosphere doubles.
The idea that the Gulf Stream could stop has led to horrific fantasies on the silver screen, although it has not found much understanding among scientists.
But a recent report published in the acclaimed journal Science suggests that climate researchers have underestimated the possibility of a collapse.
Wei Liu and fellow researchers at the Scripps Institute have made some calculations that suggest that the Gulf Stream may end if the climate gets warmer, which means that warm ocean water may stop flowing to colder regions.
Scientists argue that this could result in a significant cooling of the North Atlantic and neighboring territories.
“If this is true, the situation will change dramatically for Norway,” says Rasmus Benestad of the Meteorological Institute, a Norwegian climate researcher, after reviewing the material in Science.
If the new report is to be believed, the Gulf Stream could become a third weaker within a hundred years, and in two centuries cease to exist altogether.
NB! Please note that the term "Gulf Stream" does not initially mean an ocean current just off the coast of Norway. Check out the facts!
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The multiple names of the Gulf Stream create confusion
When it comes to the Gulf Stream, be especially careful. In fact, we are talking about three different systems, and only one of them is the real Gulf Stream:
AMOS / Atlantic Ocean Circulation: A grandiose system of currents in the Atlantic Ocean that carries water from the equator to the poles and cold water back to the equator.
Gulf Stream: May be considered an offshoot of the AMOS, carrying warm water to the north. It is divided in two, most of the water flows to the east or northeast, there, which is called the North Atlantic Current.
Norwegian Atlantic Current: An offshoot of the North Atlantic Current that continues in the Norwegian Sea and further north along the coast of Norway. The name Gulf Stream is often misused to refer to the Norwegian Atlantic Current. It is sometimes also called the "Norwegian Gulf Stream".
Changes in the "salt budget"
The new study differs from previous studies on the Gulf Stream in that it estimates the salt content of the ocean differently.
Traditionally, it was believed that the Gulf Stream would remain fairly stable despite the warming climate, and that weakening, and even then moderate, could be "only" in the coming centuries.
Many scientists believe that these predictions were not correct enough, new calculations show that the ocean current in the Atlantic Ocean is much more sensitive to changes in temperature and salt content than previously thought.
Wei Liu and colleagues say the changes have already begun. The circulation in the Atlantic Ocean has already become weaker in recent centuries, although there is no complete certainty about this.
A vicious circle that cannot be stopped
What could happen to the Gulf Stream is an example of a classic tipping point in the climate system, writes German climate researcher Stefan Rahmstorf of the Potsdam Institute in a commentary on an article in Science.
If the current is weakened, the inflow of salt water will decrease, which in turn will contribute to the fact that the water will settle less. And thus, the motor of the ocean current itself will become less powerful.
“This is a tipping point where it becomes a vicious circle that cannot be stopped. But it is still unclear where this tipping point is,”says Ramstorf.
Two years ago, Ramstorf himself published a rather controversial report, which says that the Atlantic meridional circulation (AMOS) will be much weaker.
Significant Implications for Norway
If the results of the new study are supported, it could mean that the calculations regarding the climate of Norway will have to be changed in the future, says Rasmus Benestad of the Meteorological Institute.
“This could have big consequences for Norway. The forecast for the next 50 years could change completely.”
If ocean heat transfer changes, countries like Norway and England could get colder in the future than current projections suggest.
“What is happening to the Gulf Stream can counteract global warming. Maybe the climate will be stable for some time? In that case, we'll be lucky,”says Benestad, who explains that the effects of a weakening Gulf Stream will primarily be visible in parts of the world.
He adds that another impact will be a possible change in the usual storm routes off the coast of Norway.
He sees no signs of a weakening current off the Norwegian coast
Oceanologist Svein Østerhus of Uni Research in Bergen doesn't see the situation as dramatic.
Since 1965, oceanographers from Bergen have been measuring the branch of the Gulf Stream that runs along the Norwegian coast. In the language of professionals, this is called the Norwegian Atlantic Current.
“We are not seeing any weakening of the Norwegian Atlantic Current. On the contrary, there is a tendency to increase it,”says Esterhus.
It is possible that the ocean current off the coast of Norway may continue to exist as before, even if the large-scale circulation in the south of the Atlantic Ocean becomes weaker.
"These are two factors, which, on the one hand, are interconnected, and on the other, independent of each other."
The others should also continue this research
Nonetheless, Esterhus is taking the new report seriously.
"These are such serious questions, in particular due to the melting of ice in Greenland, that the idea that this could weaken the Gulf Stream in the future, including off the coast of Norway, does not seem unnatural at all."
Now, other researchers must decide how much they will trust the findings of the study by Wei Liu and co.
“My opinion is that their results have a right to exist. But it is quite possible that they made some mistakes, so it is up to others to check these results,”says Rasmus Benestad.
Stefan Ramstorf agrees with him.
"I hope this ominous finding will inspire as many groups of scientists as possible to continue their research."
Astrid Rommetveit