Israel Plans to Increase Natural Gas Exploration in Its Mediterranean Blocks: The Eastern Mediterranean Region Remains Prospective

     Israel recently announced that it is launching a new competitive process to search for natural gas in its blocks in the Mediterranean Sea. Energy and Infrastructure Minister Eli Cohen announced that the country will open five new blocks for exploration, covering an area of approximately 7,100 sq.km. The ministry estimates that hundreds of BCM of natural gas could be discovered.

     As reported by the Jerusalem Post:

“Natural gas is a strategic asset that strengthens our economic and diplomatic standing in the world in general, and in the Middle East in particular,” Cohen said.

“Therefore, my policy is to expand natural gas exploration, bring international energy giants to invest in Israel, and increase natural gas production, for the local market and for export,” he added.

     The ministry confirmed that six exploration licenses were granted to a group that includes the State Oil Company of the Republic of Azerbaijan (SOCAR), London-headquartered BP, and Israel’s NewMed Energy. Seismic surveys are planned in the near future. They also plan to expand production capacity from the Tamar and Leviathan reservoirs. Israel also recently signed the largest natural gas export deal in its history. The gas will be exported to Egypt and will help strengthen bilateral ties between the two neighboring countries.

“The ministry is acting to ensure the supply of natural gas to the local market, while maintaining an attractive environment for investments and competitive prices,” Energy and Infrastructure Ministry Director-General Yossi Dayan said.

“The competitive procedure is intended to increase the supply of natural gas, increase competition, attract additional players, and assist in the continued development of the market. The correct way to ensure competition and reduce prices is through expanding supply, and not through burdensome regulation,” Dayan added.

“Alongside its contribution to the market, the procedure will strengthen Israel’s energy resilience and its regional and international standing for the coming years,” he concluded.

The Energy and Infrastructure Ministry’s Natural Resources Administration Director, Chen Bar Yosef, added: “The procedure will enable new and significant entrepreneurs to take part in the development of the Israeli natural gas sector and in the regional energy map. As we have already seen in the past, activity in Israel holds significant potential for success. We intend to act with every relevant international factor and encourage it to submit a bid as part of this important procedure.”

 

Eastern Mediterranean Exploration

     The map below shows the exclusive economic zones for each country bordering the Eastern Mediterranean. It also shows a once-proposed subsea pipeline from Israel’s fields to Turkey. I believe Israel, Egypt, and Cyprus are the only producers in the Eastern Mediterranean thus far, but it is believed that significant potential remains.

     The EIA and Eurasia Review notes:

“The development of midstream infrastructure for natural gas in the Eastern Mediterranean is still emerging. As of July 2025, Egypt is the only country in the region with liquefied natural gas (LNG) export capacity, which Israel uses to deliver natural gas outside the region. Cyprus aims to use Egypt’s LNG infrastructure once its offshore fields begin producing, which could lead to competition with Israel for Egypt’s LNG export capacity. Jordan and Lebanon are developing LNG infrastructure that would allow additional natural gas import flexibility.”

     Egypt’s offshore production, which is closer to land, is also maturing. However, there have been some new finds. Egypt’s Zohr field, operated by Eni, came online in 2017 and is the country’s largest natural gas discovery to date. Egypt consumes more oil & gas than the other countries owing to its higher population. Israel produced very little domestic natural gas before the Tamar field came online in 2013. Recent discoveries offshore Cyprus include three new fields. However, first production is not expected until 2028 for one field and 2031 and 2035 for the other two fields, respectively. Lebanon and Syria don’t have any Eastern Mediterranean production, but may explore it in the future. The table below shows Eastern Mediterranean projects, operators, and production timelines.

 

References:

 

Israel launches new search for natural gas in the Mediterranean Sea. James Genn, Jerusalem Post. July 6, 2026. Israel launches new search for natural gas in the Mediterranean Sea | The Jerusalem Post

Eastern Mediterranean Energy Profile – Analysis. Energy Information Administration. Eurasia Review. December 8, 2025. Eastern Mediterranean Energy Profile - Analysis - Eurasia Review

Three April 2026 Papers in ‘Science Advances’ Address AMOC: 1) Overturning Transport Change at AMOC’s Western Boundary May Indicate Weakening; 2) Volcanic Activity at the Onset of the Younger Dryas May Have Disrupted AMOC; and 3) Ridge-Regularized Linear Regression Model Shows AMOC Weakening of 51%, Higher Than Climate Models, Which Predict a Weakening of 32%: Thermohaline Circulation Post #5

  

   This post reviews three recent papers involving the AMOC and thermohaline circulation, all published by Science Advances in April 2026.

 

1) Overturning Transport Change at AMOC’s Western Boundary May Indicate Weakening

     This paper identifies a “meridionally consistent decline in deep western overturning transport across these latitudes over the past two decades” at AMOC’s western boundary and is put forth as evidence for AMOC weakening, something which is widely acknowledged to be occurring. 

     In their introduction, the authors note that the hard data available “are relatively short compared to simulations and reconstructions, making it difficult to discern whether we are observing decadal-scale fluctuating variability or a declining trend of the AMOC.” That is another uncertainty in whether or by how much the AMOC is weakening. They also address measurement uncertainties, which they say they resolve in the current study.

“Additional uncertainty in direct AMOC observations arises from their associated methodologies. The existing observational arrays, located at various latitudes within the Atlantic Ocean, have used different observation schemes and equipment, as well as methods of computation. Consequently, there is no consistent method for continuously estimating the strength of the AMOC across the Atlantic basin in modern times. Hence, we apply a common treatment to the now available observational data, to obtain consistent overturning transport estimates, which can then be used collectively to address research questions about the long-term variability of the AMOC.”

     The paper is concerned with developing consistent and accurate methodologies to measure and monitor AMOC weakening.

“…accurately monitoring the AMOC across various latitudes of the Atlantic basin presents a considerable challenge for the physical oceanography community.

“As proposed by Hughes et al. (36), long-term observations of OBP is a promising approach for monitoring large-scale ocean circulation, as they provide high accuracy while minimizing the influence of mesoscale variability. Our results further indicate that the estimation of the deep western overturning transport, derived from the western OBP gradient or equivalently the western geostrophic transport shear, can act as a reasonable method to capture interannual variability of the AMOC and indicate trends related to signals occurring at the western boundary.”

 

2) Volcanic Activity at the Onset of the Younger Dryas May Have Disrupted AMOC

     The Younger Dryas period occurred from 12,900 years ago to 11,700 years ago, and during that 1200-year period, the Earth returned to a glaciated state after it had begun an interglacial period. The question often asked is what triggered it? Comets or asteroids were one possible answer, but no evidence of that has been found. This study suggests that volcanic activity was the cause. The paper relies on geochemical and stratigraphic data. A well-dated, continuous sedimentary record spanning the Younger Dryas onset is utilized. Osmium isotope ratios (187 Os/188 Os) were used to detect volcanic eruptions. The eruptions were determined to occur from 12,980 to 12,870 years ago, which occurred just before, during, and after the Younger Dryas onset. The continuous stratigraphic sections utilized are located in Texas and Florida.

     The paper notes:

“…the YD is traditionally interpreted in terms of changes in North Atlantic circulation, particularly disruptions to the Atlantic Meridional Overturning Circulation (AMOC) following meltwater input.”

     This paper supports that assumption and offers geochemical and stratigraphic evidence that previous attempts to evaluate a possible volcanic cause failed to provide. They also serve to disprove extraterrestrial impact as a cause. As the abstract notes:

“The magnitude and hemispheric asymmetry of this volcanic activity imply forcing of sufficient magnitude capable of disrupting the Atlantic Meridional Overturning Circulation and triggering rapid Northern Hemisphere cooling. These findings provide multiproxy, regionally consistent evidence for a volcanically driven perturbation at the onset of the YD, offering a robust alternative to impact-based explanations.”

     If they are correct, then climate forcing via volcanic eruptions emitting large quantities of aerosols can affect the climate enough to initiate changes in the AMOC and initiate cooling.

 

 

3) Ridge-Regularized Linear Regression Model Shows AMOC Weakening of 51%, Higher Than Climate Models, Which Predict a Weakening of 32%

     This paper utilizes statistical methods to arrive at an AMOC weakening that is more intense than the middle and most likely climate scenario, SPP2-4.5. However, they also show and emphasize the uncertainties and the huge differences in the prediction of AMOC weakening for the different climate scenarios, something I pointed out in my previous post. The graph below shows all the climate models used and includes the SSP5-8.5 scenario now abandoned by the IPCC. The graph also visually exemplifies that the historical data, only available since around 2000, is very small compared to the modeled data. As mentioned in the previous post, the changes seen in the small amount of real data available could be caused by decadal changes rather than or in addition to anthropogenic climate forcing.  

“Because of the large differences between the historical simulations of absolute AMOC strength in the respective climate models, the model uncertainty of AMOC is very large for each scenario in Fig. 1A.”

“This suggests that most of the total uncertainty in the future AMOC is due to differences between climate models (model uncertainty).”

     This is illustrated in the graphs below:

“According to a recent IPCC report, a slowdown of more than 50% can be called a “substantial weakening of the AMOC.” This substantial weakening could have important implications for future adaptation plans in various regions affected by the AMOC, around the Atlantic and in teleconnected regions. This refinement toward stronger AMOC decline is mainly due to SSS fresh biases in the South Atlantic regions and SST cold biases in the North Atlantic regions in the CMIP6 MMM. This highlights the importance of biases in climate models for their ability to represent future AMOC fate.”    

     Perhaps it seems a little odd that the results of their statistical analysis of the model data arrive at a point just above the point where the weakening becomes “substantial” compared to previous MMM methods, which are well below that “substantial” threshold. I am a bit skeptical of their statistical methods, but I am not qualified to evaluate them. I am not suggesting deliberate bias, just noting conclusions that conveniently support a more catastrophic position, though not much more.

“Overall, the best OC method in terms of leave-one-out error, using the information from multiple observable variables, suggests an AMOC slowdown that is 60% stronger than estimated by the MMM. This could result in significant modifications to the climate change projections for various regions worldwide and introduce additional risks that stakeholders must consider, such as the potential for extensive drying in the Sahel region.”

     I think the main issue with this paper is that the historical data is quite sparse, which makes the projections more dependent on the models used and the model assumptions. As noted in the abstract, the change in projections is mainly a result of correcting a bias in sea surface salinity (SSS) in the South Atlantic region.

“This refinement mainly results from correcting a bias in South Atlantic surface salinity, consistent with recent studies emphasizing its role in the proximity to an AMOC tipping point. This more substantial AMOC weakening has key implications for future adaptation strategies.”

     This study is interesting but does not seem to resolve uncertainties nor prove that a tipping point is imminent or even possible, despite sort of suggesting it in the above quote.

 

References:

 

Volcanic forcing of global climate cooling at the Younger Dryas onset preserved in North American sediments. Lucien Nana Yobo, Alan D. Brandon, Sydney O’Brien, Jessi J. Halligan, and Michael R. Waters. Science Advances. 29 Apr 2026. Vol 12, Issue 18. Volcanic forcing of global climate cooling at the Younger Dryas onset preserved in North American sediments | Science Advances

Meridionally consistent decline in the observed western boundary contribution to the Atlantic Meridional Overturning Circulation. Qianjiang Xing, Shane Elipot, William E. Johns, David A. Smeed, Ben I. Moat, and John W. Loder. Science Advances. 8 Apr 2026. Vol 12, Issue 15. Meridionally consistent decline in the observed western boundary contribution to the Atlantic Meridional Overturning Circulation | Science Advances

Observational constraints project a ~50% AMOC weakening by the end of this century. Valentin Portmann, Didier Swingedouw, Omar Khattab, and Marie Chavent. Science Advances. 15 Apr 2026. Vol 12, Issue 16. Observational constraints project a ~50% AMOC weakening by the end of this century | Science Advances

Study Suggests Greenland Ice Melt is Weakening AMOC, but There is No Impending Tipping Point Seen: Using the SSP5-8.5 Scenario Makes the Results Questionable: Thermohaline Circulation Post #4

     The AMOC is part of a heat redistribution engine that moves heat along the thermohaline circulation currents in the Atlantic Ocean, which connects the deep, shallow, and surface parts of the ocean. The AMOC is the main region where warm tropical surface water sinks to depth. That water has higher salinity since warmer surface water experiences more evaporation, which makes it denser, causing it to sink, which happens mainly in a region between Greenland and Iceland.

     The current paper, published in Science Advances, explores the effects of Greenland meltwater on the AMOC now and in the future. According to the article about the study in Phys.org:

“A recent Intergovernmental Panel on Climate Change (IPCC) model found that none of the Coupled Model Intercomparison Project phase 6 (CMIP6) models show an abrupt AMOC collapse during the 21st century.”

     Other studies have suggested that Greenland meltwater does weaken the AMOC, but there is no indication in current data of abrupt, irreversible changes ahead to 2300, which is how far into the future the simulations go.

“However, it currently remains an open question whether these meltwater-induced AMOC changes are associated with tipping point characteristics such as abruptness and irreversibility. In addition, the physical mechanisms of how Greenland meltwater affects the AMOC beyond 2100 have, to our knowledge, not yet been explored," write the authors of the new study.”

     The simulations do suggest that the effects of meltwater on the AMOC will increase after 2100.

“The model indicated that AMOC weakening is roughly linear and scales smoothly with cumulative CO2 emissions when meltwater is added, arguing against a classic tipping-style jump.”

     The researchers simulated the reversibility of a strong weakening of the AMOC and concluded that reversibility can occur but will take time, likely a couple of centuries.

     They also noted that the simulation was limited and simulations with different assumption parameters should be conducted. Indeed, they should, as will be seen later in this post.

“The team notes that the results are based on a single climate model, and other models may route meltwater differently or have different AMOC stability. They say that similar tipping-focused tests should be repeated across multiple climate models to see whether the non-abrupt and reversible result is robust.”

     Indeed, in the abstract, they note that most climate modeling has not incorporated the potential impacts of Greenland meltwater, which increases the uncertainty of whether the AMOC could shift abruptly. Their study is one of the first to assess the possibility of a sudden shift, and their conclusion seems to be that it is very unlikely to lead to one before 2100, but the probability increases after that under the scenario that they use.

 

The Simulations are Using CIMP’s SSP5-8.5, Which Has Been Widely Recognized as Extremely Unlikely and Has Been Officially Abandoned by the IPCC

  The graph below from the paper shows the projections for increases in Greenland meltwater. They are on the left y-axis. The CO2 concentrations are given on the y-axis. I found those high concentrations baffling and noticed that they are using the IPCC’s abandoned CIMP SSP5-8.5 scenario. This, in my view, makes the simulations not credible as such a catastrophic scenario as SSP5-8.5 is now widely recognized as extremely unlikely. I saw an article recently calling for tracking research that uses SSP5-8.5 so that those papers could be flagged for bias. Why would they not choose the middle of the road SSP2-4.5 scenario? On the second graph below, I drew in the red line, which shows a very rough SSP2-4.5 scenario trajectory. Since the prescribed runoff meltwater follows CO2 concentrations It becomes quite clear that using SSP2-4.5 will considerably change the results of the simulation towards much less change of a catastrophic weakening before or after 2100. In the SSP 5-8.5 scenario, atmospheric CO2 concentrations would be about 1250ppm in 2100. In the SSP2-4.5 scenario, which is far more likely, the CO2 concentrations would be less than half of that at about 600ppm and max out in 2300 between 700 and 800ppm. Thus, we can see quite clearly that using SSP5-8.5 changes the results by a large factor. I would like to see these scenarios run with a much more likely scenario. It may be good to know the absolute worst scenario parameters for an endpoint reference, but if those are highly unlikely anyway, why would the researchers choose it with their limited research dollars? Perhaps the simulations were run before the IPCC officially abandoned SSP5-8.5, which happened a few months ago. However, since SSP 5-8.5 had run out of favor long ago, why are they even considering it? We could have gotten more information and more realistic information by running SSP2-4.5.  

I added the red line to show what the CO2 concentrations would be in the SP2-4.5 scenario. The purple line would also change under the SP2-4.5 scenario. The amount of meltwater in the SP5-8.5 scenario would be roughly 4 times the amount in the SP2-4.5 scenario. 

     As noted above, the amount of meltwater in the SSP5-8.5 scenario would be roughly 4 times the amount in the SSP2-4.5 scenario. That is a huge difference.

     The graph below likely carries the same bias as the previous one, since the amount of meltwater they are projecting is likely going to be much less, since they are relying on a highly unlikely scenario.

     They also simulated shifts in the AMOC source region, which is currently between Greenland and Iceland, but again, if they are predicting far more meltwater than is likely, then how could such projections be meaningful?

     Unfortunately, the use of the SP5-8.5 scenario ruins it for me. However, we should be happy that a highly unlikely absolute worst-case scenario, such as SSP5-8.5, was not catastrophic. That means that a more realistic simulation would show that fears of an AMOC collapse are not warranted, and weakening will likely be quite manageable. Is the basis of the debate about AMOC weakening a belief on one side in the SSP5-8.5 scenario? If so, then the debate is likely settled, and there is no impending threat, at least for the next several hundred years. If there is no tipping point in sight with SSP5-8.5, there will likely be no tipping point at all. That is my take.

 

    

 References:

 

Greenland meltwater adds to AMOC weakening, but updated model finds no tipping point in sight. Krystal Kasal. Phys.org. July 4, 2026. Greenland meltwater adds to AMOC weakening, but updated model finds no tipping point in sight

Limited impact of Greenland meltwater on abruptness and reversibility of future Atlantic overturning changes. Oliver Mehling, Katinka Bellomo, Federico Fabiano, Marion Devilliers, Michele Petrini, Susanna Corti, and Jost von Hardenberg. Science Advances. 19 Jun 2026. Vol 12, Issue 25. Limited impact of Greenland meltwater on abruptness and reversibility of future Atlantic overturning changes | Science Advances

Compare IPCC Scenarios Interactive. UCAR Center for Science Education. Compare IPCC Scenarios Interactive | Center for Science Education

 

 

 

 

Ocean Heat Transport Causes the Bulk of “Warming Hole” aka “Cold Blob” Heat Content Variations, Not Surface Fluxes, According to New Paper: Thermohaline Circulation Post #3

     This paper addresses a property of the AMOC as a “warming hole” or “cold blob” in the North Atlantic Ocean. The cold blob has dropped in temperature by an estimated 1 degree C since 1900. It is currently the only place in the world to have cooled significantly since then. It is acknowledged that both ocean heat transport and surface fluxes contribute to the cooling, but there is debate about which is the dominant cause. Both temperature and salinity drive ocean circulation via density changes, which move water from surface to depth. The cold blob is the result of the slowing of the AMOC currents. Helen Coffey notes in an article for The Independent.

“This is a complex and nuanced area of science. Oceanographers and climate scientists have speculated that two different factors could be causing this level of cooling: a combination of changing ocean currents and changes in surface heat fluxes. However, they are “debating the relative importance of the two mechanisms”, says Flavio Lehner, a climate scientist and assistant professor at Cornell University. Consensus has yet to be reached.”

     A major concern about the AMOC is that as climate change increases, Greenland ice melt and very cold fresh water is added to the ocean near the AMOC. This cold, fresh water floats, and this disrupts and slows the sinking effect at the AMOC. It is thought that cooling in the subpolar North Atlantic region affects European heatwaves by altering the path of the jet stream and how far south or north it moves across the continent. The AMOC could be a major reason why Europe enjoys milder temperatures at higher latitudes. If it weakens, it could cool the continent more than desired, according to models.

     Dr Lee de Mora of Plymouth Marine Laboratory noted:

“Because the cold blob is so big, it also affects the air above it. The jet stream, a fast-flowing current of air flowing from west to east, hits the cold blob and is forced to go around it. “That’s when you get these heat dumps and cold snaps, where it hits the bottom and then it creates a wave in the jet stream that passes over Europe,” says Dr De Mora. “That’s what’s so scary about the cold blob – it has this huge impact on everything around it.”

     Interestingly, Coffey notes:

“The very question of whether the Amoc is “weakening” is controversial. That’s because there simply isn’t enough data to say for sure yet – direct observations of the ocean have only been recorded for the past 25 to 30 years, and experts say we need at least 60 years’ worth of data to come to a definitive conclusion.”

     That is in contrast to my previous post, where researchers seemed confident that the AMOC was indeed weakening, and more than previously estimated. Without enough data, they should not be as confident, one would think, especially with the methods used in the current paper, which, as noted below, come with “sizeable uncertainties.”

     The researchers used indirect observations. or “reanalysis data” from a computer model fed with real-world measurements wherever they were available.

“It’s in many ways the best we can do if we want to look into the time before satellite measurements and ocean moorings, so before about 1980 – but it comes with sizable uncertainties,” Lehner points out.

“Dr Evans says that scientists who look at direct observations of the ocean would be more “cautious” when it comes to making sweeping statements about whether or not the Amoc is significantly weakening.”

“However, all of the big climate models, such as those from the IPCC reports, are universally predicting that the Amoc will weaken this century. “There is that conflict between: this is what the models tell us; this is what we expect from the science; and this is what the observations are doing,” says Dr de Mora. “It is still an open question, but we are almost certain that the Amoc will weaken this century.”

“Within that assumption rumbles another debate. There are essentially two fiercely opposing “camps” of scientists, according to Lehner, “one that is increasingly concerned that the Amoc might collapse before long and one that thinks it is more stable.”

     While I think this is a reasonable scientific debate, its implications could be severe if the weakening is definite and such a possibility can be exploited by those who favor catastrophism to use as more evidence, real or potential, to advocate for climate change policies that restrict fossil fuel use.

     The most recent IPPC report says the weakening is more likely to be a gradual decline than a rapid “catastrophic” collapse. It is noted that scientists agree that the effects of a strong weakening or a collapse would be dire, but there is disagreement about the severity of the threat, and whether or by how much it will weaken. Lehner seems to favor a precautionary approach:

“Reducing greenhouse gas emissions is the only known way to avoid the collapse, so from a risk reduction perspective, we have enough information to take this scenario seriously.”

     In other words, we can fix it, but only if we act now. That sounds like the familiar pressure sales pitch.

     The paper was published in Geophysical Research Letters. In the paper’s abstract below, I think the most important conclusion is:

“…multidecadal heat content variations are generally larger and more tightly correlated with ocean heat transport than with surface heat flux variability.”

     As can be seen in Figure 5 from the paper below, the ocean heat content rate of change matches closely with the implied ocean heat transport anomaly, much better than it matches the surface heat flux anomaly.

     The paper’s conclusion notes:

“Surface heat loss appears to respond as a negative feedback to heat content changes: periods of increasing heat content coincide with periods of large surface heat loss. Thus from observational data, we reach the same conclusion as (K. Y. Li and Liu, 2025) did based on the analysis of model results.”

     They don’t rule out that surface heat flux contributes. They state that the presence of the blob indicates a slowdown or weakening of the AMOC. I think there is widespread acknowledgement of an AMOC weakening, but little agreement on the magnitude of the weakening and how much it will weaken in the future.

“On shorter time scales this includes a robust observed weakening of the Gulf Stream over the past 4 decades (Piecuch & Beal, 2023), consistent in magnitude with the 15% AMOC weakening inferred from the subpolar SST data (Caesar et al., 2018), and an ocean density reduction in the subpolar gyre since 1950 which “is suggestive of a long-term AMOC weakening of 2.2 Sv or 13%” (Chafik et al., 2022).”

     The fundamental argument is about the stability of the AMOC and whether it will remain stable. Time will tell us more.

 

 

 

References:

 

Multidecadal Atlantic “Warming Hole” Heat Content Variations Are Caused by Ocean Heat Transport, Not by Surface Fluxes. Stefan Rahmstorf, Jan Jendrkowiak, Ruijian Gou, Lijing Cheng, Angel Ruiz-Angulo, and Halldór Björnsson. Geophysical Research Letters. 28 May 2026. Vol. 53, Issue 11. Multidecadal Atlantic “Warming Hole” Heat Content Variations Are Caused by Ocean Heat Transport, Not by Surface Fluxes - Rahmstorf - 2026 - Geophysical Research Letters - Wiley Online Library

We’re in a heatwave – so why is a ‘cold blob’ causing so much concern? Helen Coffey. The Independent. July 7, 2026. We’re in a heatwave – so why is a ‘cold blob’ causing so much concern?

Recent Data and Model Simulations Suggest Atlantic Meridional Overturning Circulation (AMOC) Could Weaken Faster Than Expected: Thermohaline Circulation Post #2

     

      This is the first of four studies I am reviewing about the weakening of the Atlantic Meridional Overturning Circulation (AMOC). The late geochemist Wally Broecker is responsible for a lot of the early science of thermohaline circulation, as I recounted in the previous book review post. This is the second of five posts about thermohaline circulation.

     New research published in Nature suggests the AMOC, which conveys warmer surface water from the tropics that has higher salinity, and is denser due to more evaporation, to deeper water in a region of the North Atlantic where the denser water sinks into the deeper ocean. The research suggests that the AMOC conveyor belt could slow by as much as 50% by 2100. That’s a sharper drop than many earlier projections and raises new questions about how quickly impacts could unfold. This would be considered to be a significant weakening of the thermohaline circulation. Brocker, who died in 2019, considered that there was a risk of the AMOC weakening or slowing down, but very little chance of it completely collapsing, which could theoretically lead to the Earth shifting to an icehouse mode. The AMOC is a major feature of Earth’s climate system and is considered to be stable and not in danger of stopping, just weakening a little faster than previously estimated. As Jennifer Gray of the Weather Channel notes, the thermohaline circulation system distributes heat around the ocean and the earth and affects global temperatures and rainfall patterns.

     The new study claims to have narrowed the uncertainty about the rate and degree of AMOC weakening by combining model simulations with real-world observations, such as ocean temperature and salinity patterns. Gray writes:

“The study also suggests the decline may not be gradual and predictable. Instead, it could approach critical thresholds earlier than expected, increasing the risk of abrupt changes.”

     She notes that the impacts of a significant weakening of the AMOC by 2100 are a matter of debate. Modeling suggests that it could accelerate sea level rise along the U.S. East Coast, change storm tracks, and affect marine ecosystems. Other possible effects are a cooling of Northern Europe and disrupting the tropical monsoons on which people depend. It could also alter the carbon budget of the ocean.    

     Gray notes about the study that the uncertainties are a result of a lack of detailed data coverage for local and regional salinities and temperatures, since small changes in either can affect the estimations considerably. This might be another good reason for the Trump administration to abandon, which they already have fortunately, previous plans to dismantle our ocean monitoring systems.  

     The paper’s abstract notes that the AMOC’s effects on the carbon cycle and subsequently global temperature remain seriously underexplored. As noted, predicting those impacts is fraught with uncertainties.

     The paper discusses possible past AMOC collapses and slowdowns:

“Paleoclimate data provide strong evidence that AMOC changes caused abrupt climate changes during glacial periods. Although the mechanisms of glacial climate changes are different from those caused by anthropogenic emissions, model simulations show that global warming may cause a weakening and even a complete shutdown of the AMOC in the future. Despite no significant signal from direct observational measurements, some studies based on indirect proxies suggest that the AMOC is weakening, and is currently in its weakest period in a thousand years, although the reliability of such reconstructions is still debated. The IPCC AR6 concludes that, with medium confidence, AMOC shutdown is unlikely this century. However, recent research suggests this risk may be underestimated, highlighting the potential for substantial, persistent global impacts if tipping points were crossed. Modeling studies also show that the weakening or shutdown of the AMOC can affect the functioning of the marine carbon cycle and cause additional changes in CO2.”

      The researchers define an AMOC collapse as:

“…a rapid weakening of the AMOC to a nearly complete shutdown with the maximum strength below 5 Sv.”

     They also note that the CO2 response to an AMOC shutdown remains highly uncertain, even though they predict an increase of atmospheric carbon dioxide by 47–83 ppm and an increase in the global average temperature of 0.2 deg C. Below, they give an explanation of why they think the atmospheric CO2 increase would be much more than previously estimated if the AMORC were to collapse, as modeled by their CLIMBER-X simulator. They focus on the simulations showing that higher baseline CO2 levels in the atmosphere would lead to more CO2 outgassing in the Southern Ocean near Antarctica.   

“Our results show that AMOC collapse induces much stronger CO2 increases at higher baseline CO2 levels (compared to 280 ppm), which is further supported by paleoclimate evidence. Recent studies show that CLIMBER-X reproduces critical aspects of millennial-scale climate variability during glacial times61. In particular, consistent with more complex models (e.g., Vettoretti et al. 202262; Malmierca-Vallett et al. 202463), it produces Dansgaard-Oeschger like events as part of internal variability of the climate system under mid-glacial ice sheets and low CO261. It is widely accepted that these Dansgaard-Oeschger events are associated with abrupt changes in the AMOC, involving transitions between weak and strong AMOC states. However, Dansgaard-Oeschger variability is not associated with a complete collapse of the AMOC and ice core data show only minor responses of atmospheric CO2 of  ~ 5 ppm during Dansgaard-Oeschger events64. This is consistent with what was found in model simulations (e.g., see ref. 65) and also with what CLIMBER-X produces60. As a response to a complete AMOC shutdown following freshwater input into the North Atlantic from Heinrich events during glacial times, CLIMBER-X produces a much larger response in atmospheric CO2 of  ~ 15 ppm, which is again in good agreement with ice core data during Heinrich Stadials60. The process behind this large CO2 increase is a sudden onset of convection in the Southern Ocean in response to an AMOC shutdown60. Several studies have suggested that deep Southern Ocean convection can promote the release of stored oceanic carbon37,66,67. Because CLIMBER-X reproduces past climate-carbon cycle variability linked to AMOC changes, we have confidence in its response to a potential AMOC collapse under warmer conditions. In our simulations, the comparatively larger atmospheric CO2 increase is primarily associated with the development of deep Southern Ocean convection, which ventilates carbon-rich deep waters and drives substantial outgassing to the atmosphere. The CO2 increase in response to an AMOC shutdown grows strongly with higher baseline CO2 levels (Fig. 3c). Higher CO2 baselines correspond to larger ocean carbon inventories (Supplementary Fig. 11), contributing to substantially more carbon to be released during a collapse, suggesting that the amplitude of past glacial CO2 responses is not a proper analog for the expected amplitude of CO2 increase in a warmer, higher-CO2 world. Consistent with this, other models show that in warmer climates a sudden Southern ocean convection onset can raise atmospheric CO2 by  ~ 40 ppm66, much larger than observed glacial-period changes. Our results suggest that the same Southern Ocean convection-driven mechanism could operate under future warmer conditions, producing a substantially larger CO2 response than during glacial times.”

    

Media Reactions to This Paper

     Since the AMOC has long been considered a potential tipping point for global climate and since the paper predicts that we are moving faster than previously estimated towards that potential tipping point, there have been some media reactions to the paper. One of the authors, though not the lead author, is Johan Rockstrom, of the Potsdam Institute for Climate Impact Studies. He is the originator of the planetary boundaries model of earth systems analysis that suggests we have crossed or are close to crossing several planetary boundaries, basically tipping points, which have various impacts. That model is debatable and many, including me, have criticized it as being too catastrophist and not taking into account things like resource abundance and being overly reliant on simulations and modeling. Papers in which he is an author seem to draw a lot of media attention, usually in support of catastrophism.

     Sometimes sensible, sometimes not, environmentalist (and sometimes loudmouth) George Monbiot wrote an article about the paper in The Guardian entitled: A catastrophic climate event is upon us. Here is why you’ve heard so little about it. That is the very definition of a doomsday headline. His article seems to take the worst-case scenarios and the most extreme possible ranges of predictions given in the paper and run with them as if they were the only numbers. He says that the new modeling shows that an AMOC collapse would not be low probability as previously estimated, but high probability. I believe that what the paper is saying is that the probability increases, but nowhere does it say it moves from low probability to high probability. He acts as if this one paper that suggests an increase in probability is the most important discovery of the year or decade. His predisposition toward catastrophism led him to describe an AMOC collapse as:

“…potentially leading to a “hothouse Earth” in which very few survive.”

     He spends the rest of the article badmouthing people like William Nordhaus, who developed climate impact economics projections, and Bjorn Lomborg, who has spoken out against climate catastrophism, and Bill Gates. More importantly, he misrepresents the paper’s implications and its level of uncertainty and shouts out that catastrophe is imminent when, in reality, that does not appear to be the case at all.

 

References:

 

Scientists warn a critical Atlantic current could weaken faster than expected, reshaping global weather. Jennifer Gray. The Weather Channel. April 23, 2026. Scientists warn a critical Atlantic current could weaken faster than expected, reshaping global weather

A catastrophic climate event is upon us. Here is why you’ve heard so little about it. George Monbiot. Opinion. The Guardian. April 23, 2026. A catastrophic climate event is upon us. Here is why you’ve heard so little about it | George Monbiot | The Guardian

Collapse of the Atlantic meridional overturning circulation would lead to substantial oceanic carbon release and additional global warming. Da Nian, Matteo Willeit, Nico Wunderling, Andrey Ganopolski & Johan Rockström. Communications Earth & Environment volume 7, Article number: 295 (March 2026). Collapse of the Atlantic meridional overturning circulation would lead to substantial oceanic carbon release and additional global warming | Communications Earth & Environment