How close is the tipping point?
New studies on the Atlantic current system assess the threshold between natural fluctuations and a climate change-driven evolution
Is the Atlantic Meridional Overturning Circulation (AMOC) slowing down? Is this system of ocean currents, which is so important for our climate, likely to come to a halt in the future? Are the observed variations a natural phenomenon or are they already caused by human-induced climate change? Researchers from various scientific disciplines use a wide range of methods to better understand the gigantic oceanic circulation.
“The AMOC provides Europe with a mild climate and determines seasonal rainfall patterns in many countries around the Atlantic. If it weakens over the long term, this will also affect our weather and climate. Other consequences could be a faster rise in sea levels at some coasts or a reduction in the ocean’s ability to take up carbon dioxide and mitigate climate change”, Professor Dr. Mojib Latif, Head of the Research Unit: Marine Meteorology at GEOMAR Helmholtz Centre for Ocean Research Kiel, explains. “We depend on the AMOC in many ways – but so far, we can only guess how it will develop, and whether and how strongly we humans ourselves will push it towards a tipping point where an unstoppable collapse will take its course.”
Using observational data, statistical analyses and model calculations, a team led by Professor Latif has therefore examined changes in the current system over the past one hundred years in greater detail. The results have now been published in the scientific journal Nature Climate Change. According to the researchers, part of the North Atlantic is cooling – a striking contrast to the majority of ocean regions. All evaluations indicate that since the beginning of the 20th century, natural fluctuations have been the primary reason for this cooling. Nonetheless, the studies indicate that the AMOC has started to slow down in recent decades.
Climate models consistently predict a significant slowing of the current system in the future as carbon dioxide emissions continue to rise, the ocean continues to warm, and the melting of the Greenland ice sheet accelerates. “Our results confirm earlier scientific findings. But the question remains how long we will remain in the realm of natural variability and when climate change will take control of the AMOC. Then the trend would only be in the direction of weakening and risks could increase significantly”, co-author and GEOMAR meteorologist Dr. Jing Sun points out.
Better observational data are needed to determine the critical limit, the authors conclude. “Systematic and sustained measurements of the changes already taking place across the Atlantic also allows us to say with greater certainty what influence climate change has on the AMOC current system today and in the future”, says Professor Dr. Martin Visbeck. The head of the Research Unit Physical Oceanography at GEOMAR is also co-author of the new publication. “At the moment, we do not see any clear signs that the system is slowing down dramatically – rather, it is fluctuating. But since the latest climate models agree that a significant reduction will occur, we should know how much longer we are on the relatively safe side of natural change.”
Latif, M., Sun, J., Visbeck, M., Bordbar M.H. (2022): Natural variability dominates Atlantic meridional overturning since 1900. Nature Climate Change, doi 10.1038/s41558-022-01342-4.
12 responses to “NEW STUDY: “Part Of North Atlantic Is Cooling”…”Natural Fluctuations Have Been Primary Reason””
It would be very interesting, and enlightening, if the authors had stated clearly what in their conception is the difference between “slowing down” and “fluctuating”. Otherwise, the last quoted phrase is plain nonsense.
(I mean: is “fluctuating” the same as “oscillating” (regular or irregular)? An oscillatory process can “slow down”, or “up”, or alternatingly down and up, its frequency without changing its amplitude; and also the other way round: reduce or increase amplitude without changing frequency; or both at the same time)
il est effarant et choquant que des affirmations comme “ralentissement significatif du système actuel à l’avenir à mesure que les émissions de dioxyde de carbone continuent d’augmenter,” soient intégrés dans une étude qui se veut sérieuse et prise en considération.
En quoi l’évolution du CO2 est-elle démontrée comme influençant le débit de l’ALOC Quel en est le processus … à part la reprise de l’allégation : CO2 > température des océans SST > ralentissement des flux naturels.
quel scientifique décent peut faire le lien entre CO2 et SST … puisque le CO2 n’intervient qu’en mode radiatif et que la surface de l’eau est insensible aux IR au delà d’une infime couche
Des personnes instruites ne vont tout de même pas prendre le risque du ridicule en spécifiant que : le CO2 … et essentiellement celui des hommes (5% des flux annuels), chauffant l’atmosphère (ce qui est FAUX 2/3 du temps dans l’histoire du climat sur 450 millions d’années) et … cet air surchauffé, réchauffe lui-même les océans ! confirmant ainsi la célèbre efficacité du chauffage de l’eau des pates … par sèche-cheveu !
My French is not that great – but I think your last sentence sums it up for me and deserves a wider audience…
“thus confirming the famous efficiency of heating pasta water… by hair dryer!”
Just how does the air temperature change an ocean current?
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Several sentences describing limited observations imbebbed in propaganda.
Does the magnetic pole migration have any effect on Greenland ice formation?
The effects and factors from humanity are poorly defined and vague. It would be nice to have a chart demonstrating the proxy determined history of temperature and the AMOC. That would provide a perspective.
We are all doomed, but not just yet. Send more money for a bigger computer.
Confusion in the study of the AMOC is caused by claims in several different alarmist papers that both speeding up and slowing down of the AMOC cause warming to NH climate. Whatever it does – it’s us and it’s bad.
First principles of course support that the AMOC is one of many current systems moving ocean heat from equator to pole. So reducing its strength will move less heat leading to high latitude cooling.
The AMOC has been shown to be associated with the spectacular and extreme warming-cooling excursions known as Dansgaard-Oeschger (DO) events – “micro-interglacials” happening from 50-15 kya during the last glacial interval. In these events, warming excursions of 10C or more were clearly associated with weakening of the AMOC:
AMOC has always varied under its own internal dynamic and also influenced by weak astrophysical forcing. It is probably the strongest source of north hemisphere climate variability, and also causes the big difference in climate between the north and south hemispheres: namely, that on long timescales, NH climate is relatively more variable while that of the SH changes more slowly and less often. For instance the DO events with acute and rapid climate change in the last glacial period characterised the NH only, not the SH. They were driven by the AMOC.
It is a positive feedback within the AMOC that accounts for its spontaneous nonlinear oscillation resulting in the AMO. Downwelling highly saline deep water in the Norwegian Sea draws up more surface water from the Caribbean, self-reinforcing the circulation of the AMOC. But in complex systems like climate positive feedbacks are not runaway “tipping points” as naively believed by alarmists. Instead they are self-terminating. Increased warm water transport to the Arctic melts more fresh water from Greenland which chokes off the Norwegian Sea downwelling. So the cycle returns to the start and continues.
oh no not this old crap again!
Like every other incorrect forecast for the last 50 years this one keeps raising its ugly head.
If there is money in it I suppose this dead horse will keep getting flogged.
What we Earthlings need to worry about is the new Minimum we are in AND even worse the possibility of the Poles flipping. Imagine flying in a plane and the poles flip…”Where are we at?”
I worry more about the Pole flip than cooler weather. I live on a farm and grow my food and raise animals for food.
BUT a Pole flip will cause INCREASED radiation hitting Earth…get ready for MANY Mutations.
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