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Hurricane Melissa: One of the Most Powerful Atlantic Storms Ever Recorded

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Satellite image capturing Hurricane Melissa on October 28th

Associated Press/Alamy Stock Photo

Jamaica is experiencing severe impacts from Hurricane Melissa, which is forecasted to be the most powerful hurricane to strike the Atlantic Ocean, bringing up to 1 meter (40 inches) of rainfall. It is virtually certain that global warming has intensified Hurricane Melissa.

According to studies, the warm waters that fueled the storm’s rapid intensification are 500 to 700 times more likely to be influenced by climate change. This was highlighted by Daniel Guilford and his team at Climate Central, a non-profit based in the US.

“The figure of ‘500 to 700 times more likely’ is substantial,” Guilford noted. “This clearly indicates that the extreme temperatures witnessed around Melissa wouldn’t be possible without human-induced climate change.”

Tropical cyclones like Melissa derive their energy from warm ocean waters. When storms pass over warmer surfaces, more water vapor is generated. As this moist, warm air rises and cools, condensation occurs, releasing latent heat. This process generates energy that fuels tropical cyclones.

In the central Caribbean, where Melissa rapidly intensified into a Category 5 hurricane, sea surface temperatures were recorded at 1.4 degrees Celsius (2.5 degrees Fahrenheit) higher than typical for October. These elevated temperatures extend to significant depths, resulting in an abundance of thermal energy within the oceans.


As Melissa stirs the ocean, sea surface temperatures remain elevated, bringing deeper, warmer water to the surface. Conversely, if only a shallow warm layer exists, colder water rises, depleting the storm’s energy.

“Hurricane Melissa is shaping up to be a perfect storm. The warm ocean has been rapidly escalating in intensity recently, while its slow movement could lead to extensive rainfall as it makes landfall,” said Lianne Archer, a researcher at the University of Bristol in the UK. “These conditions are largely intensified by the additional heat present in the oceans and atmosphere driven by climate change.”

The combination of strong winds and heavy rainfall poses a severe threat to Jamaica. Reports indicate that three individuals have already lost their lives as preparations continue for the storm, anticipated to make landfall around 11 a.m. or 12 p.m. local time.

“This presents one of the most alarming scenarios,” commented Hannah Cloke, a researcher from the University of Reading in the UK. “The nation will bear deep and lasting scars from this storm, making recovery a challenging endeavor for impacted regions.”

Historical studies of past disasters indicate that such events can stifle economic growth for years. Though some economists speculate a quick recovery could spur growth, this notion has often proven to be unfounded.

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Source: www.newscientist.com

Why Hurricane Melissa Ranks Among the Most Powerful Atlantic Storms in History

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Satellite image of Hurricane Melissa captured on October 28

Associated Press/Alamy Stock Photo

Jamaica is facing severe impacts from what is possibly the strongest hurricane to hit the Atlantic Ocean. Current forecasts predict up to 1 meter (40 inches) of rainfall. There’s little doubt that global warming has intensified Hurricane Melissa.

According to the authors, the warm waters that sped up Melissa’s intensification are 500 to 700 times more likely due to climate change. Initial assessments by Daniel Guilford and his colleagues at Climate Central, a U.S. non-profit organization, reveal this.

“‘500 to 700 times more likely’ is an astonishing figure,” Guilford stated. “This clearly indicates that the extreme temperatures observed around Melissa would not be feasible without human-induced climate change.”

Tropical storms like Melissa draw their energy from warm ocean waters. The hotter the sea surface, the more water vapor is generated when a storm passes above it. As the warm, moist air rises, the vapor condenses and releases latent heat, warming the air and encouraging further condensation. This process fuels tropical cyclones.

In the central Caribbean, where Melissa rapidly intensified into a Category 5 hurricane, sea surface temperatures were 1.4 degrees Celsius (2.5 degrees Fahrenheit) above the October average. Since these extreme temperatures penetrate to significant depths, there is abundant excess thermal energy available in the ocean.

This indicates that sea surface temperatures remain elevated as Melissa churns the ocean and draws up cooler, deeper water. Conversely, if only a thin layer of warm water exists, the storm brings up cold water, cutting off its energy supply.

“A perfect storm continues to build for Hurricane Melissa. The warm ocean has been rapidly strengthening over recent days, and its slow movement may bring additional rainfall as it makes landfall,” stated Lian Archer, a researcher at the University of Bristol in the UK. “Many of these conditions are being exacerbated by heightened heat in the oceans and atmosphere attributable to climate change.”

The combination of powerful winds and extreme rainfall poses a significant risk of severe damage to Jamaica. So far, three lives have been lost as preparations for the storm continue, which is expected to make landfall around 11 a.m. or noon local time.

“This is one of the most troubling scenarios,” remarked Hannah Cloke, a researcher at the University of Reading in the UK. “The entire nation will suffer long-term and potentially permanent damage from this storm, and recovery will require significant effort for those affected.”

Research into past disasters suggests that such events can depress economic growth for decades. While economists propose that quicker recovery or even growth driven by recovery efforts is possible, these notions have generally proven to be overly optimistic.

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Source: www.newscientist.com

Rare Artifacts Discovered in Sweden Illuminate Iron Age Metal Trade Between the Atlantic and Baltic Seas

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A recent study by archaeologists investigated round heavy metal objects from Seldal, located in the Haland region of western Sweden. Initially thought to be Bronze Age artifacts due to their shape and size, these objects were determined to be composed of copper-zinc-tin-reed alloys typical of the Iron Age and later periods.

Plano Convex Ingots from Seldal in Harland, Sweden. Image credit: Sabatini et al., doi: 10.1016/j.jasrep.2025.105312.

The ancient ingots were uncovered in the village of Seldal on Sweden’s west coast during the fall of 2022.

This artifact has been identified as a Plano-Convex Ingot.

“Plano-convex ingots, commonly known as ‘bread’ ingots or ‘casting cakes,’ were prevalent during the Bronze Age, though they vary in size, shape, and composition,” explains Serena Sabatini, a researcher at the University of Gothenburg.

“These artifacts are typically round with flat top surfaces and various inflated convex bottoms.”

“They are created by pouring molten metal into shallow molds or cavities in the ground.”

“Most of these ingots exhibit a rough, ‘bubbly’ top surface, indicating they were poured into an open casting mold, while the bottom remains smooth, as it was not exposed to air during production.”

“Due to their straightforward manufacturing process, they are widely found across Eurasia and were utilized both in prehistoric and historical periods.”

The Särdal Ingot measures 14-15.3 cm in diameter, approximately 2.5 cm thick, and weighs 1223.5 grams.

Notably, the ingot’s surface displays significant corrosion, especially on the rough, raised area.

The overall dimensions and weight of the ingot initially suggested it could be a Bronze Age find.

“At first, we believed the Seldal Ingot dated back to the Bronze Age,” the archaeologist noted.

“However, since it was found alone and not dated within an archaeological context, we opted for isotopic and chemical analysis to determine its composition and estimate a time frame.”

The analysis yielded surprising results, revealing that the ingot was made from copper-zinc-tin-reed alloys typical of the Iron Age and later.

“The findings emerged thanks to the collaborative spirit of the international scientific community exploring archaeological topics, allowing us to identify the isotopic and elemental characteristics of the Seldal ingots, which closely resemble artifacts from two sites found in the Iwawa Lakeland region of northeastern Poland.

Research into the Baltic Sea area, which had a robust network connected to western Sweden and southern Scandinavia during the Roman Iron Age, indicates that the alloys from both Seldal and Iwawa Lakeland were present in the region during the latter half of the 1st millennium BCE.

“Thus, we propose that the Plano Convex Ingots from Harland and the ingots from Poland represent the outcomes of a metallic maritime trade linking Scandinavia, the Baltic Sea, and the Iberian Peninsula.”

Their paper will appear in the October 2025 edition of Journal of Archaeological Science: Report.

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Serena Sabatini et al. 2025. Iron Age Metals Trade between the Atlantic and the Baltic Sea: New insights from the first complete Plano-Convex Ingot found in Sweden and Ingot Rod in Iwawa Lakeland, northeastern Poland. Journal of Archaeological Science: Report 66:105312; doi:10.1016/j.jasrep.2025.105312

Source: www.sci.news

A Potential New Mega-Earthquake Hotspot Could Emerge Under the Atlantic Ocean

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New structural faults have been discovered beneath the Atlantic Ocean, potentially heightening the risk of significant earthquakes and tsunamis that could impact the region. This finding is based on a recent study published this week in Natural Earth Science.

For centuries, the reason behind Portugal’s susceptibility to major earthquakes, despite its distance from prominent fault lines, has puzzled scientists.

On November 1, 1755, Lisbon was struck by a catastrophic earthquake registering 8.7 on the Richter scale, resulting in the deaths of tens of thousands and triggering a tsunami that reached the Caribbean. In 1969, a magnitude 7.8 tremor off the Portuguese coast killed 25 individuals.

“One of the challenges is that these earthquakes occur on completely flat plains and are distant from fault lines,” stated Professor Joan Duarte, a geologist at the University of Lisbon and the study’s lead author, as reported in BBC Science Focus.

“Following the 1969 earthquake, it became clear that there were signs of a subduction belt, indicating something unusual in that region.”

The subduction zone, where one tectonic plate moves under another, is responsible for some of the planet’s most destructive “megathrust” earthquakes, including the catastrophic events in the Indian Ocean in 2004 and Tohoku in 2011. However, the Atlantic Ocean has traditionally been viewed as relatively stable, with its plates slowly drifting along the mid-Atlantic ridge.

Duarte’s team compiled earthquake records and utilized computer models from the Horseshoe Abyss Monkey Plain, a deep seabed located southwest of Portugal. They uncovered evidence that the mantle—a hot, dense layer beneath the Earth’s crust—is undergoing a process known as peeling.

“The base of the plate is separating as if peeling off, like the sole of a shoe,” Duarte explained. “The first moment of realization came when I thought, ‘Oh, there’s something out there.’ The second was when our computer models confirmed this peeling process.”

This artwork illustrates the 1755 Lisbon earthquake. A combination of earthquakes, tsunamis, and subsequent fires nearly obliterated the Portuguese capital – Credit: Getty

This phenomenon is unusual in oceanic crust, which typically behaves like a “crème brûlée,” resting on a more pliable layer below due to its rigid buoyancy.

In this instance, it appears that water has been infiltrating the rock for millions of years, chemically weakening it and enabling the mantle mass to descend toward the Earth’s depths.

The research suggests that we might be witnessing the emergence of a new subduction zone in the Atlantic Ocean, which could ultimately reunite Africa, Europe, and the Americas into future supercontinents.

For now, however, the immediate concern is the potential for earthquakes.

“A significant earthquake will occur again,” Duarte emphasized.

“If there’s a forecast for rain tomorrow, you’d take an umbrella,” he added. “We don’t need to know the exact time of the rain, just that we must be prepared.”

“The same goes for earthquakes. While we can’t predict when major ones will strike, we understand the likelihood, so we need to be ready.”

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About our experts

Joan Duarte is an assistant professor of tectonics at the University of Lisbon and serves as the president of the Department of Tectonics and Structural Geology within the European Union of Geosciences. His research has been featured in journals such as Geophysical Research Letters, Nature Communications, and Geology.

Source: www.sciencefocus.com

NOAA Forecasts Above-Average Atlantic Hurricane Activity

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The National Marine and Atmospheric Administration (NOAA) anticipates an active Atlantic hurricane season, expecting more storm activity than usual.

“We’re really monitoring a typical season,” stated Ken Graham, a meteorologist and director of the National Weather Service. “We’re expecting a range of storms with names, from 13 to 19.”

A storm receives its name when wind speeds reach 39 mph or more. The forecast indicates 6 to 10 storms may develop into hurricanes, with wind speeds exceeding 74 mph. NOAA also predicts the occurrence of major hurricanes in category 3 or higher.

While the forecast does not specify whether a hurricane will make landfall, where it will do so, or how many will impact the U.S. coast, it is crucial to prepare now, according to meteorologists.

“This is a good time to gather your supplies and prepare your kit,” Graham advised. “We need to be prepared; currently, there are no long lines for supplies, gas, plywood, or water.”

Graham noted that the above-average forecasts are influenced partly by warmer ocean temperatures, a trend linked to climate change.

“The warm ocean temperatures align with our expectation of a more active season,” he explained during a news conference.

Forecasters have also predicted increased activity from the West African monsoon, suggesting that storms may develop off the African coast and travel across the Atlantic towards the U.S.

This hurricane forecast arrives as many National Weather Service offices face staffing shortages, following staff cuts and voluntary retirement programs initiated during the Trump administration.

In the early months of 2025, nearly 600 personnel have left the National Weather Service, creating gaps in staffing. However, the agency’s leadership assured that the National Hurricane Center, a division of the National Weather Service, is adequately resourced.

“We are fully staffed at the Hurricane Center and prepared to respond; this is our top priority for this administration,” stated NOAA acting manager Laura Grimm.

The nation’s 122 local forecast offices have been significantly affected and face numerous vacancies. Many will be responsible for predicting regional impacts such as flooding and rainfall following hurricanes.

“Our office will ensure that the necessary resources are in place to issue warnings whenever there’s a hurricane threat,” Graham added, “and we are working on solutions to maintain long-term staffing.”

Hurricane season spans from June 1st to November 30th, generally peaking in late summer and early fall.

NOAA’s predictions are largely consistent with forecasts from various external research groups, including those from universities, government bodies, and private organizations.

On average, external research groups have forecasted eight Atlantic hurricanes for 2025. The website, managed by Colorado State University and the Barcelona Supercomputing Center, monitors and compiles annual forecasts.

Last year, NOAA projected a record hurricane season, which featured 18 named storms and 11 hurricanes. Five hurricanes made landfall in the U.S., including Hurricane Helen, which impacted Florida’s Gulf Coast and caused severe inland flooding in North Carolina, resulting in over 150 fatalities.

Additionally, Hurricane Milton made landfall as a Category 3 storm in Siesta Key, Florida, spawning 46 tornadoes.

Both hurricanes experienced rapid intensification, a phenomenon where a storm strengthens significantly right before hitting land.

This intensification is increasingly likely due to global warming. High sea surface temperatures can enhance rapid strengthening, similar to trends observed recently. A 2023 study found that tropical cyclones in the Atlantic are about 29% more likely to rapidly intensify from 2001 to 2020 compared to 1971 to 1990.

Source: www.nbcnews.com

As Key Atlantic Currents Decelerate, US East Coast Confronts Rising Sea Levels

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AMOC is a system of ocean currents that circulates water in the Atlantic Ocean.

NASA/Goddard Space Flight Center Scientific Visualization Studio

The decline in significant Atlantic currents is contributing to flooding linked to rising sea levels in the northeastern United States, which are already affected by climate change. As global temperatures increase, a total collapse of the Atlantic Meridional Overturning Circulation (AMOC) could exacerbate sea level rise.

“If AMOC collapses, this will greatly increase flood frequency along the US coastline, independent of major storms,” states Liping Chan from the Geophysical Fluid Dynamics Laboratory at the US National Oceanic and Atmospheric Administration (NOAA) in New Jersey. “Even a partial reduction in current strength can have significant consequences.”

The warm waters melting ice sheets and rising sea levels are influenced by climate change, which leads to uneven rates of sea level rise across different regions. For instance, some coastal areas have subsided, increasing the relative rate of sea level rise there. Local sea levels are also affected by the circulation of heat, water, and salt in the ocean, with warm, fresh water occupying more volume than cold, salty water.

Over the past few decades, sea levels along the northeastern US coast have risen 3-4 times faster than the global average. The slowing of AMOC—responsible for transporting warm water from lower latitudes to the North Atlantic, where it cools and sinks—has long been considered a potential cause of this phenomenon. As this circulation weakens, warm deep water expands, pushing more water onto the shallow continental shelf.

AMOC strength varies naturally over different timescales, and climate change has contributed to its slowdown as the North Atlantic and its waters have become warmer and clearer in recent decades. However, it remained uncertain whether this decrease significantly affected sea levels.

Chang and her team utilized tidal gauge measurements from the New England coast to reconstruct local sea levels dating back over a century. Alongside a steady rise due to climate change, they identified significant fluctuations between low and high sea levels every few decades. Low sea levels correlated with periods of weak AMOC, while high sea levels were also aligned with these intervals, which brought more frequent coastal flooding.

The researchers then employed two distinct ocean models to quantify the impact of AMOC intensity variations on local sea levels. While the primary driver of change was the steady rise due to climate change, they discovered that weakened AMOCs significantly increased sea-level-related flooding. In multiple coastal regions, they noted that the slowdown in AMOC has contributed to delaying flooding by 20-50% since 2005.

Given that the natural cycle of AMOC strength is largely predictable, Zhang asserts that these findings enable researchers to forecast potential flooding events up to three years in advance. This foresight can guide long-term infrastructure planning and emergency preparedness.

“This highlights the critical role of AMOC in [sea level rise],” remarks Chris Hughes, who was not involved in the research, from the University of Liverpool in the UK. “It’s not merely theoretical; it’s evident in the real world.”

It remains unclear how much of the recent AMOC weakening is attributable to climate change versus natural variability. Nevertheless, the findings bolster predictions that if AMOC were to completely collapse due to climate change, significant portions of the US East Coast could experience a surge in sea levels.

Hughes warns that if AMOC nearly collapses, sea levels could rise by around 24 centimeters. “While it may not seem dramatic, even a small increase can have a substantial effect.”

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Source: www.newscientist.com

The complexity of Viking expansion into the North Atlantic was underestimated.

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Vikings played a prominent role among the peoples of the North Atlantic, and the populations founded by them might be expected to be genetically similar and homogeneous. New research suggests that the Icelandic and Faroese people had distinctly different founding fathers. This result is consistent with a scenario in which the male population of the Faroe Islands was formed by a more diverse population from the more diverse Scandinavian population than from neighboring Icelanders. Furthermore, this study conclusively shows that there is no evidence of post-founder admixture between the Faroese and Icelandic gene pools.

The Faroe Islands consist of an archipelago of 18 small islands located in the North Atlantic Ocean between southern Norway, Iceland, and Scotland. As a result of their demographic history and relative geographical isolation, the Faroe Islands, like other North Atlantic island populations, are genetically homogeneous compared to mainland populations. Historical and archaeological sources report that the Faroe Islands were settled around 800 AD by Vikings, primarily from western Norway. However, increasing evidence suggests that these islands were settled earlier, perhaps by Celtic monks or other people from the British Isles. Carbon dating of peat moss and barley grain supports two pre-Viking periods of settlement, approximately 300-500 AD and 500-700 AD. More recently, scientists detected sheep DNA in archaeological deposits from 500 AD, and based on modern whole-genome data, the original founding of the Faroe Islands occurred between 50 and 300 AD. estimated that it may have been two to three centuries earlier than previously thought. Based solely on archaeological findings. Image credit: Oscar CR

From the 8th century to about 1050 AD, Vikings roamed the Atlantic in longships all the way to Newfoundland, Labrador, and Greenland, as well as exploring the Mediterranean and Eurasia.

Among the places they are known to have settled are the Faroe Islands, an archipelago of 18 islands in the North Atlantic Ocean.

They probably weren’t the first. Archaeologists have found evidence that these islands have been inhabited since about 300 AD, perhaps by Celtic monks or other people from the British Isles.

However, according to Fairinga Sagawritten around 1200, a Viking chieftain called Grimur Kamban settled in the Faroe Islands between about 872 and 930 AD. But where in Scandinavia did Grimur and his followers come from?

“We have strong evidence here that the Faroe Islands were colonized by a diverse group of male settlers from multiple Scandinavian populations,” said University of Louisville researcher Dr. Christopher Tillquist. .

In this study, Dr. Tillquist and his colleagues genotyped 12 “short tandem repeat” (STR) loci on the Y chromosome of 139 men from the Faroese islands of Bordoloi, Streymoy, and Suzloj.

They assigned each man to the most likely haplogroup. Each haplogroup has a different known distribution across Europe today.

They compared the genotype distribution to that found in 412 men from Norway, Sweden, Denmark, Iceland, and Ireland.

This allowed the team to reconstruct the source population of the founders of the Viking population.

Advanced analysis showed that the Faroe Islands sample range was similar to the broader Scandinavian genotype range, whereas the Icelandic genotypes were different.

The authors also developed a powerful and innovative genetic method called “variational distance from modal haplotype” to analyze SNP (single nucleotide polymorphism) variation within STRs.

This has led to the “founder effect” (vestiges of random loss of diversity during historical colonization by a small number of people) that remains in the genetic composition of male populations in the Faroe Islands and Iceland today. was able to clarify.

“Scientists have long thought that the Faroe Islands and Iceland were settled by similar Nordic peoples,” Dr Tillquist says.

“However, our new analysis showed that these islands were founded by people belonging to different gene pools within Scandinavia.”

“One group of diverse Scandinavian origins settled in the Faroe Islands, while a more genetically distinct group of Vikings colonized Iceland. They had separate genetic characteristics that continue to this day. Masu.”

“Despite their geographic proximity, there appears to have been no subsequent interbreeding between these two populations.”

“Our findings show that Viking expansion into the North Atlantic was more complex than previously thought.”

“Each longship that sailed to these distant islands carried a different genetic heritage, and not just Vikings.”

“We can now trace the separate journeys of conquest and settlement, revealing a more nuanced story of Viking exploration than is told in history books.”

of findings appear in the diary frontiers of genetics.

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Alison E. Mann others. 2024. Genetic evidence points to distinct patrilineal colonization of the Faroe Islands and Iceland. front. Genet 15;doi: 10.3389/fgene.2024.1462736

Source: www.sci.news

Vital Atlantic currents at risk of collapse, warn scientists

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Overview

A recent report has highlighted the concerning state of Earth’s snow and ice, indicating that various key climate tipping points are more likely to be reached than previously thought. These include significant ice melt leading to severe sea level rise and disruptions to crucial ocean currents controlling the Atlantic heat cycle.

The report reveals alarming statistics such as Venezuela losing its last glacier this year, Greenland’s ice sheet losing an average of 30 million tons of ice per hour, and the impending collapse of Thwaites Glacier, also known as the “terminal glacier.” This collapse could potentially result in the rapid disappearance of Antarctic ice.

Compiled by over 50 leading snow and ice scientists as part of the International Cryosphere Climate Initiative, the report summarizes the conditions for 2024, highlighting the disastrous impact of global warming on the planet’s frozen regions.

Of particular concern is the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC), which could lead to drastic changes in weather patterns, such as rapid cooling in the North Atlantic and warming in the Southern Hemisphere.

Additionally, the report underscores the rising consensus among scientists that these climate tipping points are now more likely to be surpassed, with the window for mitigating actions rapidly narrowing.

The report’s release coincided with the United Nations’ COP29 climate change conference in Azerbaijan, where global leaders gathered to address pressing environmental concerns. Despite some progress, particularly in carbon credit trading, the report emphasizes that current climate policies are inadequate to meet global climate goals.

While the scientific community continues to sound the alarm about the escalating climate crisis, there are growing fears that world leaders are failing to grasp the gravity of the situation. Urgent action is needed to address the imminent threats posed by melting ice, collapsing glaciers, and disruptions in vital ocean currents.

In conclusion, the report serves as a stark reminder of the urgent need for decisive action to combat climate change before irreversible consequences unfold.

Source: www.nbcnews.com

The Impending Collapse of Atlantic Currents: The Impact on our Planet

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The frozen River Thames is being hit by cold winds, the Mersey docks are blocked by ice floes, and crops are failing in the UK. Meanwhile, rising sea levels are flooding the east coast of the United States, and the Amazon ecosystem is experiencing disruptions due to changing seasons. The world has undergone significant changes. What has caused this?

These events may seem like scenes from a disaster movie, but a recent scientific study focusing on the Atlantic Meridional Overturning Circulation (AMOC) warns that these scenarios could become a reality as early as 2050. Learn more.

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What is AMOC, why is it vital, and what changes can we expect? Will disruptions lead to catastrophic events, and how can we address the situation?

The Importance of AMOC and Expected Changes

The AMOC, also known as the “Great Ocean Conveyor,” is a vast ocean current system that includes the Gulf Stream. It transports warm, salty water from the tropics northward into the North Atlantic Ocean. As this water cools and becomes denser, it sinks, flows back southward at depth, and eventually rises to the surface, creating a continuous circulation loop.

This circulation system moves significant amounts of heat around the Atlantic Ocean, equivalent to boiling approximately 100 billion kettles. The AMOC plays a crucial role in distributing heat input to the Northern Hemisphere and affects climate zones worldwide. Any weakening of the AMOC could lead to shifts in global climate patterns, impacting various regions.

Changes in wind patterns can also influence AMOC. Stronger winds during ice ages bolstered parts of the Gulf Stream, while in a warmer future world, wind effects might weaken the AMOC.

Evidences of AMOC Changes

Direct measurements of AMOC strength started in 2004 using the RAPID array across the Atlantic Ocean. Observations indicate a 10% decline in intensity over nearly two decades, but year-to-year variations pose challenges in determining a clear long-term trend.

Past indirect measures, such as cooling trends in southern Greenland, suggest a weakening AMOC. Salt accumulation in the South Atlantic further supports the notion of reduced heat and salt transport due to system weakening.

By studying marine sediment cores and ancient shells, paleoclimatologists have discovered that the current AMOC weakening is unparalleled in the last 1,600 years, indicating a potential 15% decline in the system’s strength.

Future Outlook for AMOC

Climate models predict a 30-50% weakening of AMOC by the end of the century if greenhouse gas emissions continue. This could result in altered weather patterns, increased extreme events, and sea level rise along certain coastlines.

A small increase in global temperatures might trigger a swift shutdown of the AMOC, leading to severe climate impacts. Understanding the potential collapse mechanisms, such as “salt feedback,” highlights the need for immediate climate action to prevent such scenarios.

Managing AMOC Risk

To mitigate the risks associated with AMOC collapse, we must urgently reduce greenhouse gas emissions, enhance climate resilience, and prepare for potential disruptions in food and water supplies. Addressing the root cause of global warming and implementing sustainable practices are crucial in safeguarding the stability of the Earth’s climate system.

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Source: www.sciencefocus.com

The Possible Collapse of AMOC: Simulations Highlight Real Danger of Stopping Atlantic Currents

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Ocean currents flowing from the tropics to the North Atlantic have a major influence on Europe's climate.

jens carsten roseman

As the planet warms, is there a serious risk that the Atlantic Current that warms Europe will slow down and stop? Yes, according to the most detailed computer simulation ever performed. The likelihood of this scenario remains highly uncertain.

“We have demonstrated that it is indeed possible with our current setup,” he says. René van Westen At Utrecht University in the Netherlands.

Now, warm water, made more salty by evaporation, flows north from the tropics along the surface of the Atlantic Ocean, keeping Europe much warmer than it would otherwise be. When this water cools, it sinks because it becomes more salty and denser. It then returns to the tropics and flows along the ocean floor into the southern hemisphere.

This is known as the Atlantic Meridional Overturning Circulation (AMOC). Studies of past climate suggest that the dramatic cooling episodes that have occurred around Europe over the past 100,000 years or so have been associated with so-called tipping points, when reverse currents slow down or stop completely, and small changes in may convert one system to another. state.

The cause is thought to be melting ice sheets. The influx of large amounts of fresh water into the North Atlantic reduces salinity, which in turn reduces surface water density and reduces the amount of water that sinks.

However, this has proven difficult to model. Most shutdown simulations require adding unrealistically large amounts of fresh water at once. Some also question whether this is a potential tipping point, since recent simulations using more advanced models have not shown any shutdowns.

Now, van Westen's team has run the most sophisticated simulation to date, which took a total of six months to run on the Dutch state-run supercomputer Sunellius. It was very expensive, he says.

Unlike previous simulations, the team added fresh water gradually rather than all at once. This created a positive feedback that amplified the effect. The decrease in salinity reduced the amount of water sinking, which reduced the amount of brine flowing north, further reducing salinity.

This eventually broke the overturning circulation, causing temperatures to rise in the Southern Hemisphere but plummet in Europe. For example, in this model, London would be 10°C (18°F) cooler on average, and Bergen, Norway would be 15°C (27°F) cooler on average. Other impacts include localized sea level rise in areas such as the East Coast of the United States.

Additionally, some of the changes seen in the model before the collapse are consistent with changes seen in the real Atlantic Ocean in recent decades.

But to cause this collapse, the researchers had to run the model for 2,500 years. And they needed to add huge amounts of fresh water. Although less than previous simulations, it is still about 80 times the amount that is currently flowing into the ocean from the melting Greenland ice sheet. “So it's absurd and not very realistic,” Van Westen said.

Furthermore, this simulation did not include global warming. The team now plans to rerun the simulation with that in mind.

“This is the most cutting-edge model in which such experiments have been performed,” he says. Peter Ditlefsen He is a co-author of a 2023 study predicting that the Atlantic overturning current could break up between 2025 and 2095, based on changes in sea surface temperatures.

The model suggests it will take large amounts of fresh water and centuries to stop the circulation from reversing, but why do we think climate models are underestimating the risk of nonlinear changes like the Atlantic tipping point? There are several, Ditlefsen said.

Climate models need to divide the world into large cubes to make their calculations workable, he says, and this has a smoothing effect. Additionally, the model has been calibrated based on how well it simulates the 20th century climate, although there was a linear relationship between greenhouse gas emissions and the resulting changes. may not be applicable in the future.

“We should expect the model to be less sensitive than the real world,” Ditlevsen says.

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Source: www.newscientist.com