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New Study Reveals U.S. Coastlines Facing Accelerated Marine Disaster Risk

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A significant ocean current system that plays a crucial role in regulating the climate across the Northern Hemisphere is projected to weaken more dramatically by the end of this century than previously anticipated, according to a new study published in Scientific Progress.

The Atlantic Meridional Overturning Circulation (AMOC) is an extensive ocean current system transporting warm water north from the tropics, releasing heat into the atmosphere before descending and returning south.

“This system essentially forms a loop that transports heat from the equator to the North Atlantic,” stated Dr. Valentin Portman, the lead author of the study from France’s Bordeaux Southwest Research Center, during an interview with BBC Science Focus.

“Warm, salty water flows north, releasing heat, thickening, sinking, and then traveling south through deep ocean currents.”

Research indicates a projected 51% slowdown by 2100, a figure approximately 60% higher than average projections derived from conventional climate models, with significantly lower uncertainty.

The weakening of AMOC could lead to severe consequences. Sea levels along the northeastern U.S. coast are already rising faster than the global average, partially due to a weakening AMOC.

Globally, the tropical rain belt is expected to weaken and shift southward, jeopardizing the monsoons on which millions in West Africa and South Asia depend for agriculture.

In Europe, these changes could result in harsher, colder winters as the conveyor belt of warm water to the continent decelerates.

Worryingly, each additional weakening increases the system’s proximity to a tipping point where complete collapse becomes more probable, posing potentially catastrophic risks.

The AMOC extends across the Atlantic Ocean, forming a part of a vast network of ocean currents – Photo credit: Getty

Understanding a Complex System

Predicting the future of AMOC as the Earth warms is notoriously challenging due to the system’s vast complexity and influence from both local and global factors.

Previous forecasts about AMOC’s future varied significantly based on the employed climate prediction models. While most agree the system is weakening, the degree of potential collapse ranges from minimal to complete failure.

The new study identified two systematic errors prevalent in much of the prevailing modeling: underestimating salinity in the South Atlantic and overestimating coldness in the North Atlantic.

These biases cause models to underestimate how dense, saline water sinks and maintains current flow across the system.

By correcting these variables using a statistical approach called ridge-normalized linear regression, seldom applied in climate research, the expected weakening escalated to 51%, significantly lowering uncertainty surrounding the results.

“Typically, only one variable is used in studies, such as a singular observation of AMOC’s strength in the past,” Portman explained.

“This study aimed to incorporate more information by leveraging multiple variables simultaneously, which is vital due to AMOC’s complexity and dependence on various processes.”

The current strength of AMOC is already notably weak. Recent observations suggest a decline of 10% to 20% since the mid-2000s, equating to hundreds of millions of gallons of water no longer flowing north each second.

A 2025 study disclosed that the recent weakening of currents has contributed to nearly 50% of flooding along the northeastern U.S. coast since 2005.

However, attributing this decline to human-induced climate change rather than natural fluctuations remains a challenge. Experts state that it may take until 2033 (with 29 years of data) to confidently distinguish between the two.

Not a Complete Collapse—But It’s Worrisome

Results from this recent study are concerning, but researchers emphasize clarity regarding what they do and do not illustrate. In the 6th assessment report, the Intergovernmental Panel on Climate Change (IPCC) expressed confidence that AMOC would diminish throughout this century, albeit with “moderate confidence” that it would not collapse by 2100.

Yet, such assurances may offer little comfort given the extensive changes that collapse could entail, whether prior to or following this century’s conclusion.

For instance, a 2025 study in Geophysical Research Letters predicted that under such circumstances, temperatures in London could plummet to -20°C (-4°F) and -48°C (-54°F) in Oslo, despite global warming driven by greenhouse gases.

As human-driven climate change causes polar ice melting, ocean salinity decreases, disrupting AMOC processes.

Moreover, a weakening AMOC risks crossing an unknown tipping point threshold. A study suggests that the AMOC may hold two stable “on” or “off” states, with reversals potentially taking thousands of years to rectify.

The exact location of this threshold remains uncertain. Extending existing models beyond the typical 2100 cutoff, a 2025 study in Environmental Research Letters indicated AMOC shutdowns could occur in 67% of high-emission scenarios and 30% under moderate conditions.

“We don’t definitively know where the threshold lies or if this situation truly applies,” Portman noted. “We can speculate that this decline, even more significant than predicted, may be approaching a tipping point.”

Critical Action Window

Portman’s team tested four distinct emissions scenarios. Three (ranging from moderate to very high) consistently yielded results of approximately 50% weakening, suggesting that many impacts of human-induced climate change could become irreversible beyond a certain threshold.

“We are introducing considerable heat into the ocean, which will persist for centuries,” Portman stated.

However, the most optimistic scenario, marked by robust and sustained emissions reductions, resulted in only about a 20% decline.

“There are two perspectives here. One is that it may be a bit too late, given significant CO2 emissions leading to long-term effects,” Portman explained.

“Conversely, if we dramatically lower CO2 emissions prior to hitting the tipping point, we can avert a serious decline.”

While Portman expresses confidence in his research’s projections for this important ocean system, he acknowledges that other significant processes may still need to be considered.

“This necessitates prudence regarding the findings,” he emphasized. “Substantial uncertainty remains in climate models concerning AMOC’s future. Addressing this issue is vital.”

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Source: www.sciencefocus.com

New Study: U.S. Coastlines Facing Accelerated Marine Disaster Risks

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A major ocean current system, crucial for regulating the climate across the Northern Hemisphere, is expected to weaken far more severely by the end of this century than previously estimated, according to a new study published in Scientific Progress.

The Atlantic Meridional Overturning Circulation (AMOC) is a vast ocean current system that transports warm water north from the tropics, releasing heat into the atmosphere, then sinking and returning south.

Dr. Valentin Portman, lead author from Bordeaux Southwest Research Center in France, explains, “This loop transports heat from the equator to the North Atlantic Ocean,” as reported by BBC Science Focus.

The warm, salty water moves north, releases heat, thickens, sinks, and subsequently flows south through deep ocean currents.

Research predicts a 51% slowdown of AMOC by 2100, approximately 60% higher than average projections from standard climate models and with considerably lower uncertainty.

The implications of a weakened AMOC could be dire. Sea levels along the Northeast Coast of the United States are already rising faster than the global average, partly due to AMOC’s decline.










Globally, the tropical rain belt is anticipated to weaken and shift south, endangering the monsoon systems vital for agriculture in West Africa and South Asia.

In Europe, these changes could result in colder, harsher winters as the warm water conveyor belt slows down.

Every further weakening brings the AMOC closer to a tipping point, increasing the chances of complete collapse with potentially catastrophic outcomes.

The AMOC stretches the length of the Atlantic Ocean, forming part of a vast network of ocean currents – Photo credit: Getty

The Importance of AMOC

Predicting the future of AMOC as global temperatures rise is notoriously challenging. Its vast, complex nature is influenced by both local and global factors.

Previous assessments of AMOC’s future varied widely between climate models. While most agree on its weakening, estimates of its collapse range from minimal to catastrophic.

The latest study identified systematic errors in some of the best existing models: underestimating salinity in the South Atlantic and overestimating temperature in the North Atlantic.

These biases lead to an underestimation of the critical process that allows dense, saline water to sink, maintaining current flow within the system.

After correcting these discrepancies using ridge-normalized linear regression — a rarely applied technique in climate science — researchers found the expected weakening of AMOC increased to 51%, considerably lowering result uncertainty.

“Typically, models use one variable as input, like past AMOC strength,” Portman noted.

“Our goal was to utilize more comprehensive data by analyzing multiple variables concurrently, considering the complexity of AMOC.”

The current AMOC is already showing signs of weakness, as evidenced by observational data revealing a 10% to 20% intensity decline since the mid-2000s — equivalent to significant volumes of water no longer flowing north each second.

According to a 2025 study, recent AMOC weakening has contributed up to 50% of flooding along the U.S. Northeast coast since 2005.

However, researchers caution that linking this decline directly to anthropogenic climate change, rather than natural fluctuations, remains uncertain until at least 2033, when sufficient data will be available.

Understanding the Risks

While the findings of this study are concerning, researchers clarify what they do and don’t imply.

The 6th Assessment Report from the Intergovernmental Panel on Climate Change (IPCC) expressed confidence that AMOC will weaken throughout this century but reported “moderate confidence” that it would avoid total collapse by the year 2100.

However, these reassurances may offer little comfort given the impact of such a collapse, whether it occurs before or after 2100.

Moreover, a 2025 study published in Geophysical Research Letters indicated that under serious collapse scenarios, severe cold temperatures could drop to -20°C (-4°F) in London and -48°C (-54°F) in Oslo, despite global warming trends.

As human-induced climate change melts polar ice, ocean salinity decreases, hindering processes driving the AMOC.

A weakening AMOC also raises the risk of breaching an unknown tipping point. According to a study, AMOC may exist in two stable states, and once reversed, it could take thousands of years to revert.

The exact location of this threshold is uncertain. A 2025 study in Environmental Research Letters revealed that under high emissions, AMOC shutdowns could occur in 67% of operations, and 30% under moderate emissions.

“The threshold remains elusive,” Portman stated, “but this accelerated decline we observe may be approaching a tipping point.”

Future Projections

Portman’s team assessed four different emissions scenarios, three of which (from moderate to very high) indicate similar 50% weakening results, suggesting that beyond a certain emissions level, many consequences of climate change become inevitable.

“We’ve introduced significant heat into the ocean, and its chilling effects will last for centuries,” Portman warned.

The most optimistic scenario, emphasizing strong and sustained emissions reductions, resulted in only a 20% weakening of AMOC.

“We can frame it two ways: it’s late, given our high CO2 emissions and their long-term impacts,” Portman said, “but we can also assert that significant reductions before reaching a tipping point can avert a serious decline.”

Currently, Portman believes his research offers a clearer view of the AMOC’s future, though he acknowledges ongoing uncertainties and the potential for additional undiscovered processes.

“That’s why it’s critical to approach these findings cautiously,” he emphasized. “Addressing uncertainty in climate models is essential for understanding AMOC’s fate.”

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Source: www.sciencefocus.com

Accelerated Melting in Antarctica May Support Key Ocean Currents

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Impact of Melting Antarctic Ice on Ocean Currents

Juan Barretto/AFP via Getty Images

The melting of Greenland’s ice sheet is predicted to hinder or disrupt the Atlantic current that helps keep Europe warm; however, meltwater from West Antarctica might help maintain this essential flow.

That said, it won’t be sufficient to prevent significant climate changes. The Atlantic Meridional Overturning Circulation (AMOC) is already down by 60% and could take up to 3,000 years to recover fully.

“I suggest caution in predicting an AMOC collapse,” states Sasha Sinnett from Utrecht University in the Netherlands. “However, my findings don’t alter what is forecasted for the next century. We may never see if West Antarctica successfully stabilizes the AMOC.”

The AMOC is a system of ocean currents that transports warm surface water from the tropics to northern Europe. Here, the water cools and sinks, then flows back south to Antarctica. This current carries an enormous amount of heat—1.2 petawatts—equivalent to the output of one million power plants, keeping Europe notably warmer than regions like Labrador or Siberia at similar latitudes. Lighter, fresher meltwater from Greenland is expected to obstruct the sinking of the denser, saltier AMOC water, thereby slowing its flow.

If the AMOC were to collapse, winter temperatures in Northern Europe could drop to almost -50℃ (-58°F). Recently, Iceland declared the closure of the AMOC as an “existing” security threat. Additionally, rising sea levels are threatening the U.S. East Coast, while Africa may face even more severe drought conditions.

A recent study indicates that even if we achieve net zero emissions by 2075 and begin reducing CO2 from the atmosphere, there is still a 25% risk of AMOC collapse. One study forecasts its closure in the coming decades, while another suggests that it will remain weakened due to Antarctic winds.

Currently, the melting of the West Antarctic ice sheet has accelerated, with some research indicating a probable complete collapse. However, the impact on AMOC remains uncertain.

The timing of the melting is crucial, according to simulations by Sinet and his team. If pulses of ancient Antarctic meltwater coincide with substantial meltwater from Greenland, the AMOC’s closure will be expedited.

Conversely, if the Antarctic water arrives about 1,000 years prior to the peak melting of Greenland, the AMOC may weaken for a few centuries but then recover over the next 3,000 years. While AMOC shows eventual recovery in all scenarios, early Antarctic melting prevents total collapse and accelerates its resurgence.

This phenomenon could be due to the relocation of the sinking, salty AMOC water moving south as lighter, fresher meltwater accumulates around Greenland, with the flow regaining strength as Antarctic melting decreases.

Though it’s improbable that West Antarctica melts at such a rapid pace while Greenland melts more slowly, these results illuminate a significant connection between AMOC and Antarctic ice melt, notes Louise Sim from the British Antarctic Survey.

“Prior to this study, the extent to which Antarctic changes could significantly influence the effects of Greenland’s ice sheet melting on the AMOC was largely unknown,” she remarks.

However, the study does not address potential feedback effects, such as shifts in wind patterns that might increase Antarctic sea ice, so this relationship needs to be explored in more complex models moving forward, she adds.

Even if rapid melting in West Antarctica prevents the AMOC from collapsing, it could still lead to sea-level rises of up to 3 meters, inundating coastal cities.

“Unfortunately, while one potential disaster may lessen the danger of another, this is little consolation,” concludes Stefan Rahmstorf from the University of Potsdam, Germany.

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Source: www.newscientist.com

The pandemic might have accelerated brain aging, even before we contracted Covid-19.

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Changes in brain structure over time

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The Covid-19 pandemic may have hastened brain aging, even prior to infection. Studies indicate that early in the outbreak, the brain may have undergone changes equivalent to 5.5 months of aging, potentially attributed to stress and shifts in lifestyle.

Many individuals suffering from long Covid report experiencing brain fog. However, the wider neurological implications of the pandemic are not completely understood a few years post-Covid-19’s emergence.

To investigate this, Ali-Reza Mohammadi-Nejad at the University of Nottingham, along with his team, trained machine learning models using 15,000 brain scans to analyze structural changes related to aging.

A model was then applied to brain scans from 996 volunteers participating in the UK Biobank Study. This comprised 564 individuals who underwent both scans prior to March 2020, which acted as the control group. The remaining 432 volunteers had one scan before March 2020 and another later, with scans averaging three years apart and a minimum gap of two years.

The research revealed that the pandemic may have induced an acceleration of brain aging by 5.5 months, as evidenced by structural changes in both white and gray matter. This effect was also observed in individuals who had recorded Covid-19 infections as part of the Biobank project.

This accelerated aging effect was notably more significant among men and those from lower socioeconomic backgrounds. However, the results may not be generalizable, as biobank participants typically exhibit better health, higher income, and less ethnic diversity than other demographics within the UK.

Researchers propose that these alterations might have been driven by the isolation and stress of lockdowns, alongside changes in lifestyle factors like physical activity and alcohol use during that period.

In their study, the authors indicate that these structural brain changes could be “at least partially reversible,” while also acknowledging limitations stemming from the study’s UK-based participant pool, suggesting that the findings may not accurately represent lockdowns’ impact elsewhere. “Our conclusions may actually underestimate the pandemic’s effects on more vulnerable populations,” Mohammadi-Nejad asserts.

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Source: www.newscientist.com

Nightmares Linked to Accelerated Biological Aging and Increased Mortality Risk

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Strategies to Prevent Nightmares, Such as Avoiding Scary Movies

Andrii Lysenko/Getty Images

Experiencing nightmares weekly may accelerate aging and significantly increase the chances of early death.

“Individuals with more frequent nightmares experience faster aging and a higher risk of premature death,” states Abidemi Otaiku from Imperial College London.

In collaboration with his team, Otaiku examined data from over 183,000 adults aged between 26 to 86 who participated in several studies, initially self-reporting their nightmare frequency over a span of 1.5 to 19 years.

The findings revealed that individuals reporting weekly nightmares are over three times more likely to die before reaching 70 compared to those who do not experience nightmares.

Moreover, the researchers noted that the frequency of nightmares is a more potent predictor of preterm birth than factors such as smoking, obesity, poor diet, or inadequate physical activity. Otaiku presented these findings at the European Neurological Society Conference 2025 held in Helsinki, Finland, on June 23rd.

The team additionally assessed participants’ biological ages by measuring telomere lengths, small DNA sequences at the ends of chromosomes that shorten with each cell division; short telomeres linked to premature aging. This segment of the study also included approximately 2,400 children aged 8 to 10, while adults contributed further biological age data using epigenetic clocks.

According to Otaiku, their research established a consistent connection between frequent nightmares and accelerated aging across various ages, genders, and ethnic backgrounds. “Even in childhood, those with frequent nightmares exhibit shorter telomeres, indicating faster cellular aging,” he remarked. In adults, this accelerated biological aging accounts for roughly 40% of their heightened risk of death.

Regarding the reasoning behind this association, Otaiku suggests two main factors. The first is the elevated levels of the stress hormone cortisol triggered by nightmares. These levels are linked to faster cellular aging. “Nightmares elicit a more intense stress response than what is typically experienced upon waking, often rousing us with pounding hearts,” he explained.

The second factor involves sleep disruption, which hinders the body’s overnight cellular repair processes. Poor sleep quality is associated with an increased risk of various health issues, including heart disease.

For those wishing to reduce their occurrence of nightmares, Otaiku suggests straightforward strategies, such as avoiding scary movies and addressing mental health issues like anxiety.

“This is a fascinating finding with a number of biological underpinnings,” said Guy Restiner from the NHS Foundation Trust at Guy and St. Thomas. However, he emphasized that further research is necessary to identify causal relationships, noting that nightmares can be associated with various medical conditions and medications that may impact the findings as individuals age.

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Source: www.newscientist.com

High-profile ocean models accelerated by custom software

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This figure shows surface currents simulated by MPAS-Ocean.Credit: Los Alamos National Laboratory, E3SM, U.S. Department of Energy

A new solver algorithm for the MPAS-Ocean model will significantly enhance climate research by reducing and improving computational time. Accuracy. This breakthrough in integrating Fortran and C++ programming is a step forward in efficient and reliable climate modeling.

On the beach, ocean waves provide soothing white noise. However, in scientific laboratories, they play an important role in weather forecasting and climate research. The ocean, along with the atmosphere, is typically one of the largest and most computationally intensive components of Earth system models, such as the Department of Energy’s Energy Exascale Earth System Model (E3SM).

A breakthrough in ocean modeling

Most modern ocean models focus on two categories of waves: barotropic systems, where the wave propagation speed is fast, and baroclinic systems, where the wave propagation speed is slow. To address the challenge of simulating these two modes simultaneously, a team from DOE’s Oak Ridge National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories has We have developed a new solver algorithm to shorten it. -Ocean, E3SM ocean circulation model, increased by 45%.

The researchers tested the software on the Summit supercomputer at ORNL’s Oak Ridge Leadership Computing Facility, a DOE Office of Science user facility, and the Compy supercomputer at Pacific Northwest National Laboratory. They ran the main simulations on the Cori and Perlmutter supercomputers at the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory, and their results were International Journal of High Performance Computing Applicationss.

Computing innovations for climate modeling

because TrilinosBecause open source software databases ideal for solving scientific problems on supercomputers are written in the C++ programming language, and Earth system models like E3SM are typically written in Fortran, the team took advantage of the advantages of For Trilinois an associated software library that incorporates Fortran interfaces into existing C++ packages to design and customize new solvers focused on barotropic waves.

“A nice feature of this interface is that you can use all the components of the C++ package in the Fortran language, so you don’t have to translate anything, which is very convenient,” said lead author Hyun, a computational earth systems scientist. Kang said. ORNL.

Improvements to MPAS-Ocean

This work is built on Research results announced before Journal of Advances in Earth System Modeling In this paper, researchers at ORNL and Los Alamos National Laboratory handcrafted code to improve MPAS-Ocean. This time, the ForTrilinos-enabled solver overcomes the remaining shortcomings of the solver obtained in previous studies, especially when the user runs his MPAS-Ocean using a small number of computing cores for a given problem size. Did.

MPAS-Ocean’s default solver is an explicit sub-solver, a technique that uses a large number of small time intervals or time steps to compute barotropic wave properties in conjunction with baroclinic calculations without destabilizing the model. Cycle dependent. If the barotropic and barotropic waves can be advanced with time step sizes of 300 and 15 seconds, respectively, then to maintain the same speed the barotropic calculation would need to complete over 20 times more iterations, a huge amount requires computational power.

In contrast, the new solver for barotropic systems is semi-implicit. That is, it is unconditionally stable, allowing researchers to use the same number of large time steps without sacrificing accuracy, saving significant time and computational power.

The community of software developers has spent years optimizing Trillinos and Fort Lilinos’ various climate applications. As such, a modern MPAS-Ocean solver that leverages this resource will outperform hand-crafted solvers and enable other scientists to accelerate their climate research efforts.

“If we had to code every algorithm individually, it would require much more effort and expertise,” Kang said. “But with this software, you can run simulations quickly and quickly by incorporating optimized algorithms into your programs.”

Future enhancements and impact

Current solvers still have scalability limitations for high-performance computing systems, but they perform very well up to a certain number of processors. This drawback exists because the semi-implicit method requires all processors to communicate with each other at least 10 times per time step, which can reduce model performance. To overcome this obstacle, researchers are currently optimizing processor communication and porting solvers to GPUs.

In addition, the team updated the time-stepping method of the pressure clinic system to further improve the efficiency of MPAS-Ocean. Through these advances, researchers are making climate predictions faster and more reliable, an essential upgrade to ensure climate security and enable timely decision-making and high-resolution forecasting, aims to be more accurate.

“This barotropic mode solver enables faster calculations and more stable integration of models, especially for MPAS-Ocean,” said Kang. “Extensive use of computational resources requires enormous amounts of power and energy, but by accelerating this model we can reduce energy usage, improve simulations, and improve performance over decades and even beyond.” It will be easier to predict the effects of climate change thousands of years into the future.”

Reference: “MPAS-ocean implicit pressure mode solver using a modern Fortran solver interface” by Hyun-Gyu Kang, Raymond S Tuminaro, Andrey Prokopenko, Seth R Johnson, Andrew G Salinger, Katherine J Evans, 2023. November 17th, International Journal of High Performance Computing Applications.
DOI: 10.1177/10943420231205601

This research was supported by E3SM and the Exascale Computing Project (ECP). E3SM is sponsored by the DOE Office of Science’s Biological and Environmental Research Program, and ECP is managed by DOE and the National Nuclear Security Administration. The DOE Office of Science’s Advanced Scientific Computing Research Program funds OLCF and NERSC.

Source: scitechdaily.com