When will a vital system of currents in the Atlantic Ocean collapse? Depends on whom you ask.
The Atlantic Ocean as seen from Sachuest Beach in Middletown. (Photo by Alexander Castro/Rhode Island Current)
This story was originally published by Grist. Sign up for Grist's weekly newsletter here.
Just below Greenland is a menacing stretch of water known as the Cold Blob. As the planet heats up, the Cold Blob remains a spooky outlier — positioned right above the area where the Atlantic Ocean's so-called conveyor belt is supposed to switch back and head south.
The Atlantic Meridional Overturning Current, or AMOC for short, comprises an enormous system of currents that carries water and nutrients across the world and plays a large part in stabilizing the global climate. For years, scientists have warned that the AMOC was slowing down, possibly nearing collapse. The Cold Blob is the most immediately visible proof of its decline, likely a result of Greenland's melting glaciers, but research on the deep water current's strength over recent years has varied wildly.
New studies published in Nature Geoscience last week and in Nature earlier this year offer some slightly encouraging news. AMOC's decline could be 'much more of a slow, gradual change, rather than an immediate change,' said David Bonan, a postdoctoral fellow at the University of Washington who served as the lead author on the Nature Geoscience study. The full collapse of the current might not be reached this century, rather than around the midcentury mark as other research has predicted.
The stakes could hardly be higher. Should the current break down, the most frightening predictions describe a world thrown into chaos: Drought could destroy India, South America, and Africa; the Eastern Seaboard of the United States would see dramatic sea level rise; and an arctic chill would spread across Europe.
'You cannot adapt to this,' said Peter Ditlevsen, the co-author of a 2023 study and an ice and climate researcher at the University of Copenhagen, in an interview with Inside Climate News. 'There's some studies of what happens to agriculture in Great Britain, and it becomes like trying to grow potatoes in northern Norway.'
A more gradual change would still cause enormous upheaval, but would give the world more time to put mitigation efforts in place.
Part of what makes AMOC's behavior so hard to forecast is that consistent monitoring of the current didn't begin until 2004, so the historical data is limited. When researchers run models to examine AMOC's behavior in the past, they sometimes get baffling results. 'The new models aren't working for AMOC,' said David Thornalley, a paleoclimatologist at University College London, who wasn't involved with the latest research. 'Some people would say we don't 100 percent know what AMOC did through the 20th century.'
The February study in Nature found that the current is more stable than expected. Winds in the Southern Ocean churn the incoming Arctic water up to the surface and send it northward again. The research showed AMOC slowing between 20 to 80 percent by 2100, but not collapsing entirely. This is obviously a pretty big range, and 'even a moderate weakening could affect rainfall patterns, sea level rise, and the ocean's ability to take up carbon,' said Jonathan Baker, lead author of the study and a senior scientist in the ocean, cryosphere, and climate group at the Met Office, the weather service for the U.K. Between 2009 and 2010, AMOC wobbled — slowing about 30 percent — and sea levels rose 5 inches between New York City and Newfoundland within a year.
The most recent study in Nature Geosciences narrowed that range to a weakening of 18 to 43 percent by 2100 after investigating how previous models were making their calculations. Models that predict an imminent collapse tend to assume AMOC is fairly strong at the moment, extending to great depths within the ocean and forcing warm surface water deep into the sea. Models that presented the current as weaker, with a shallower reach into the deep ocean, were less affected by warming surface waters.
Bonan and his team found that the North Atlantic is 'a little bit more aligned with these weaker models,' he said. 'If you warmed up the surface [water], or if you have increased sea ice melt or Greenland Ice Sheet melt, a lot of those surface properties are probably just going to stay at the upper ocean, rather than going deeper into the ocean.'
Still, Bonan highlighted the need for more advanced models that may be able to better forecast interactions between ice sheets and the ocean. Thornalley underlined those concerns — without sophisticated modeling of meltwater coming off Greenland, he said, these studies might be painting an overly rosy picture. 'If you look at what all the models do after 2100, a lot of them go on to collapse,' he said.
One problem with estimating a drop-dead date for AMOC is that researchers still don't understand when the current might reach a tipping point, a threshold that, when crossed, will have a cascading effect from which there is no return. Whether the current dies a slower or faster death won't matter in the long run if the world breaches that threshold. 'It's a good study,' Thornalley said. 'Does it make me calmer about the future? No.'
Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future. Learn more at Grist.org
SUBSCRIBE: GET THE MORNING HEADLINES DELIVERED TO YOUR INBOX
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
CNN
an hour ago
- CNN
A ‘dragon prince' dinosaur is redrawing the tyrannosaur family tree
Scientists have identified a previously unknown 86 million-year-old dinosaur species that fills an early gap in the fossil record of tyrannosaurs, revealing how they evolved to become massive apex predators. Researchers analyzing the species' remains have named it Khankhuuluu mongoliensis, which translates to 'dragon prince of Mongolia,' because it was small compared with its much larger relatives such as Tyrannosaurus rex, whose name means 'the tyrant lizard king.' The newly identified dinosaur was the closest known ancestor of tyrannosaurs and likely served as a transitional species from earlier tyrannosauroid species, according to the findings published Wednesday in the journal Nature. Based on a reexamination of two partial skeletons uncovered in Mongolia's Gobi Desert in 1972 and 1973, the new study suggests that three big migrations between Asia and North America led tyrannosauroids to diversify and eventually reach a gargantuan size in the late Cretaceous Period before going extinct 66 million years ago. 'This discovery of Khankhuuluu forced us to look at the tyrannosaur family tree in a very different light,' said study coauthor Darla Zelenitsky, associate professor within the department of Earth, energy, and environment at the University of Calgary, in an email. 'Before this, there was a lot of confusion about who was related to who when it came to tyrannosaur species. What started as the discovery of a new species ended up with us rewriting the family history of tyrannosaurs.' Tyrannosaurs, known scientifically as Eutyrannosaurians, bring to mind hulking dinosaurs like Tyrannosaurus rex and Tarbosaurus, which weighed multiple metric tons and could take down equally large prey. With short arms and massive heads, they walked on two legs and boasted sharp teeth, Zelenitsky said. But tyrannosaurs didn't start out that way. They evolved from smaller dinosaurs before dominating the landscapes of North America and Asia between 85 million and 66 million years ago, the researchers said. While Tarbosaurus, an ancestor of T. rex, clocked in at between 3,000 and 6,000 kilograms (6,613 pounds and 13,227 pounds), the fleet-footed Khankhuuluu mongoliensis likely weighed only around 750 kilograms (1,653 pounds), spanned just 2 meters (6.5 feet) at the hips and 4 meters (13 feet) in length, according to the study authors. Comparing the two dinosaurs would be like putting a horse next to an elephant —Khankhuuluu would have reached T. rex's thigh in height, Zelenitsky said. 'Khankhuuluu was almost a tyrannosaur, but not quite,' Zelenitsky said. 'The snout bone was hollow rather than solid, and the bones around the eye didn't have all the horns and bumps seen in T. rex or other tyrannosaurs.' Khankhuuluu mongoliensis, or a closely related ancestor species, likely migrated from Asia to North America across a land bridge between Alaska and Siberia that connected the continents 85 million years ago, Zelenitsky said. Because of this migrant species, we now know that tyrannosaurs actually evolved first on the North American continent and remained there exclusively over the next several million years, she said. 'As the many tyrannosaur species evolved on the continent, they became larger and larger.' Due to the poor fossil record, it's unclear what transpired in Asia between 80 million to 85 million years ago, she added. While some Khankhuuluu may have remained in Asia, they were likely replaced later on by larger tyrannosaurs 79 million years ago. Meanwhile, another tyrannosaur species crossed the land bridge back to Asia 78 million years ago, resulting in the evolution of two related but very different subgroups of tyrannosaurs, Zelenitsky said. One was a gigantic, deep-snouted species, while the other known as Alioramins was slender and small. These smaller dinosaurs have been dubbed 'Pinocchio rexes' for their long, shallow snouts. Both types of tyrannosaurs were able to live in Asia and not compete with each other because the larger dinosaurs were top predators, while Alioramins were mid-level predators going after smaller prey — think cheetahs or jackals in African ecosystems today, Zelenitsky said. 'Because of their small size, Alioramins were long thought to be primitive tyrannosaurs, but we novelly show Alioramins uniquely evolved smallness as they had 'miniaturized' their bodies within a part of the tyrannosaur family tree that were all otherwise giants,' Zelenitsky said. One more migration happened as tyrannosaurs continued to evolve, and a gigantic tyrannosaur species crossed back into North America 68 million years ago, resulting in Tyrannosaurus rex, Zelenitsky said. 'The success and diversity of tyrannosaurs is thanks to a few migrations between the two continents, starting with Khankhuuluu,' she said. 'Tyrannosaurs were in the right place at the right time. They were able to take advantage of moving between continents, likely encountering open niche spaces, and quickly evolving to become large, efficient killing machines.' The new findings support previous research suggesting that Tyrannosaurus rex's direct ancestor originated in Asia and migrated to North America via a land bridge and underscore the importance of Asia in the evolutionary success of the tyrannosaur family, said Cassius Morrison, a doctoral student of paleontology at University College London. Morrison was not involved in the new research. 'The new species provides essential data and information in part of the family tree with few species, helping us to understand the evolutionary transition of tyrannosaurs from small/ medium predators to large apex predators,' Morrison wrote in an email. The study also shows that the Alioramini group, once considered distant relatives, were very close cousins of T. rex. What makes the fossils of the new species so crucial is their age — 20 million years older than T. rex, said Steve Brusatte, professor and personal chair of Palaeontology and Evolution at the University of Edinburgh. Brusatte was not involved in the new study. 'There are so few fossils from this time, and that is why these scientists describe it as 'murky,'' Brusatte said. 'It has been a frustrating gap in the record, like if you suspected something really important happened in your family history at a certain time, like a marriage that started a new branch of the family or immigration to a new country, but you had no records to document it. The tyrannosaur family tree was shaped by migration, just like so many of our human families.' With only fragments of fossils available, it's been difficult to understand the variation of tyrannosaurs as they evolved, said Thomas Carr, associate professor of biology at Carthage College in Wisconsin and director of the Carthage Institute of Paleontology. Carr was not involved in the new research. But the new study sheds light on the dinosaurs' diversity and clarifies which ones existed when — and how they overlapped with one another, he said. More samples from the fossil record will provide additional clarity, but the new work illustrates the importance of reexamining fossils collected earlier. 'We know so much more about tyrannosaurs now,' Carr said. 'A lot of these historical specimens are definitely worth their weight in gold for a second look.' When the fossils were collected half a century ago, they were only briefly described at the time, Brusatte said. 'So many of us in the paleontology community knew that these Mongolian fossils were lurking in museum drawers, waiting to be studied properly, and apt to tell their own important part of the tyrannosaur story,' he said. 'It's almost like there was a non-disclosure agreement surrounding these fossils, and it's now expired, and they can come out and tell their story.'
CNN
an hour ago
- CNN
A ‘dragon prince' dinosaur is redrawing the tyrannosaur family tree
Scientists have identified a previously unknown 86 million-year-old dinosaur species that fills an early gap in the fossil record of tyrannosaurs, revealing how they evolved to become massive apex predators. Researchers analyzing the species' remains have named it Khankhuuluu mongoliensis, which translates to 'dragon prince of Mongolia,' because it was small compared with its much larger relatives such as Tyrannosaurus rex, whose name means 'the tyrant lizard king.' The newly identified dinosaur was the closest known ancestor of tyrannosaurs and likely served as a transitional species from earlier tyrannosauroid species, according to the findings published Wednesday in the journal Nature. Based on a reexamination of two partial skeletons uncovered in Mongolia's Gobi Desert in 1972 and 1973, the new study suggests that three big migrations between Asia and North America led tyrannosauroids to diversify and eventually reach a gargantuan size in the late Cretaceous Period before going extinct 66 million years ago. 'This discovery of Khankhuuluu forced us to look at the tyrannosaur family tree in a very different light,' said study coauthor Darla Zelenitsky, associate professor within the department of Earth, energy, and environment at the University of Calgary, in an email. 'Before this, there was a lot of confusion about who was related to who when it came to tyrannosaur species. What started as the discovery of a new species ended up with us rewriting the family history of tyrannosaurs.' Tyrannosaurs, known scientifically as Eutyrannosaurians, bring to mind hulking dinosaurs like Tyrannosaurus rex and Tarbosaurus, which weighed multiple metric tons and could take down equally large prey. With short arms and massive heads, they walked on two legs and boasted sharp teeth, Zelenitsky said. But tyrannosaurs didn't start out that way. They evolved from smaller dinosaurs before dominating the landscapes of North America and Asia between 85 million and 66 million years ago, the researchers said. While Tarbosaurus, an ancestor of T. rex, clocked in at between 3,000 and 6,000 kilograms (6,613 pounds and 13,227 pounds), the fleet-footed Khankhuuluu mongoliensis likely weighed only around 750 kilograms (1,653 pounds), spanned just 2 meters (6.5 feet) at the hips and 4 meters (13 feet) in length, according to the study authors. Comparing the two dinosaurs would be like putting a horse next to an elephant —Khankhuuluu would have reached T. rex's thigh in height, Zelenitsky said. 'Khankhuuluu was almost a tyrannosaur, but not quite,' Zelenitsky said. 'The snout bone was hollow rather than solid, and the bones around the eye didn't have all the horns and bumps seen in T. rex or other tyrannosaurs.' Khankhuuluu mongoliensis, or a closely related ancestor species, likely migrated from Asia to North America across a land bridge between Alaska and Siberia that connected the continents 85 million years ago, Zelenitsky said. Because of this migrant species, we now know that tyrannosaurs actually evolved first on the North American continent and remained there exclusively over the next several million years, she said. 'As the many tyrannosaur species evolved on the continent, they became larger and larger.' Due to the poor fossil record, it's unclear what transpired in Asia between 80 million to 85 million years ago, she added. While some Khankhuuluu may have remained in Asia, they were likely replaced later on by larger tyrannosaurs 79 million years ago. Meanwhile, another tyrannosaur species crossed the land bridge back to Asia 78 million years ago, resulting in the evolution of two related but very different subgroups of tyrannosaurs, Zelenitsky said. One was a gigantic, deep-snouted species, while the other known as Alioramins was slender and small. These smaller dinosaurs have been dubbed 'Pinocchio rexes' for their long, shallow snouts. Both types of tyrannosaurs were able to live in Asia and not compete with each other because the larger dinosaurs were top predators, while Alioramins were mid-level predators going after smaller prey — think cheetahs or jackals in African ecosystems today, Zelenitsky said. 'Because of their small size, Alioramins were long thought to be primitive tyrannosaurs, but we novelly show Alioramins uniquely evolved smallness as they had 'miniaturized' their bodies within a part of the tyrannosaur family tree that were all otherwise giants,' Zelenitsky said. One more migration happened as tyrannosaurs continued to evolve, and a gigantic tyrannosaur species crossed back into North America 68 million years ago, resulting in Tyrannosaurus rex, Zelenitsky said. 'The success and diversity of tyrannosaurs is thanks to a few migrations between the two continents, starting with Khankhuuluu,' she said. 'Tyrannosaurs were in the right place at the right time. They were able to take advantage of moving between continents, likely encountering open niche spaces, and quickly evolving to become large, efficient killing machines.' The new findings support previous research suggesting that Tyrannosaurus rex's direct ancestor originated in Asia and migrated to North America via a land bridge and underscore the importance of Asia in the evolutionary success of the tyrannosaur family, said Cassius Morrison, a doctoral student of paleontology at University College London. Morrison was not involved in the new research. 'The new species provides essential data and information in part of the family tree with few species, helping us to understand the evolutionary transition of tyrannosaurs from small/ medium predators to large apex predators,' Morrison wrote in an email. The study also shows that the Alioramini group, once considered distant relatives, were very close cousins of T. rex. What makes the fossils of the new species so crucial is their age — 20 million years older than T. rex, said Steve Brusatte, professor and personal chair of Palaeontology and Evolution at the University of Edinburgh. Brusatte was not involved in the new study. 'There are so few fossils from this time, and that is why these scientists describe it as 'murky,'' Brusatte said. 'It has been a frustrating gap in the record, like if you suspected something really important happened in your family history at a certain time, like a marriage that started a new branch of the family or immigration to a new country, but you had no records to document it. The tyrannosaur family tree was shaped by migration, just like so many of our human families.' With only fragments of fossils available, it's been difficult to understand the variation of tyrannosaurs as they evolved, said Thomas Carr, associate professor of biology at Carthage College in Wisconsin and director of the Carthage Institute of Paleontology. Carr was not involved in the new research. But the new study sheds light on the dinosaurs' diversity and clarifies which ones existed when — and how they overlapped with one another, he said. More samples from the fossil record will provide additional clarity, but the new work illustrates the importance of reexamining fossils collected earlier. 'We know so much more about tyrannosaurs now,' Carr said. 'A lot of these historical specimens are definitely worth their weight in gold for a second look.' When the fossils were collected half a century ago, they were only briefly described at the time, Brusatte said. 'So many of us in the paleontology community knew that these Mongolian fossils were lurking in museum drawers, waiting to be studied properly, and apt to tell their own important part of the tyrannosaur story,' he said. 'It's almost like there was a non-disclosure agreement surrounding these fossils, and it's now expired, and they can come out and tell their story.'
Yahoo
2 hours ago
- Yahoo
Russian scientists discover a new island in the Caspian Sea — the world's largest inland body of water
When you buy through links on our articles, Future and its syndication partners may earn a commission. A new island has appeared in the northern part of the Caspian Sea, a Russian research expedition has confirmed. The island, which does not have a name yet, is located 19 miles (30 kilometers) southwest of another island called Maly Zhemchuzhny, according to a translated statement published by the Russian state-owned news agency TASS. The island is only slightly elevated above the water level, and its surface was damp and mostly flat but covered in sand ridges at the time of the expedition, the statement said. The new island emerged due to a drop in the Caspian Sea's water levels, Stepan Podolyako, a senior researcher at the Russian Academy of Sciences' P. P. Shirshov Institute of Oceanology (IO RAS) who was on the expedition, wrote in a statement shared with Live Science. The Caspian Sea, which lies at the junction between Europe and Asia, is the largest inland body of water in the world when measured by its surface area of 143,200 square miles (371,000 square kilometers). "The occurrence of new islands in the Caspian Sea is associated with cyclical processes of long-term fluctuations in the level of [these] landlocked waters," Podolyako wrote in the statement. "Awash islands are uplifts on the seabed that come to the surface during periods of falling sea level." The Caspian Sea's levels fell during the 1930s and 1970s before bouncing back — and they started dropping again around 2010, Podolyako said. Related: Surprised Russian school kids discover Arctic island has vanished after comparing satellite images Climate change may be to blame for the recent decline, because the Caspian Sea's water levels partly depend on evaporation rates, Podolyako said. There are also tectonic shifts happening beneath the sea, which could explain changes in water levels, he added. Scientists first spotted signs of the new island in satellite images in November 2024. A pile of sand and sediment had breached the surface of the water and was beginning to dry, according to the statement in TASS — but the claim that a new island was forming remained somewhat controversial. During the recent expedition, researchers managed to approach the island to confirm its existence, but they were unable to land due to bad weather and shallow water conditions. Photographs taken from a drone revealed the island's size and some of its features, but further research is needed to describe it thoroughly. RELATED STORIES —New island that emerged from the ocean off Japan is now visible from space —Melting ice in Antarctica reveals new uncharted island —Newly discovered island is the closest land to the North Pole "A next visit to the island is planned [...] in the second half of 2025," Podolyako said. A decision about the official name of the island will then be made, depending on whether researchers find any notable characteristics to name it after. Otherwise, the island could be named after a person who has made significant scientific or cultural contributions in the area, Podolyako said. The island currently sits just inches above water level, but that could change with declining river flows into the Caspian Sea in the summer and fall, according to the statement in TASS. This may lower water levels around the island and increase its elevation.
