MARK YOUR CALENDARS
Gulf Stream current could collapse in 2025, plunging Earth into climate chaos: 'We were actually bewildered'LIKE THE END OF THE MAYAN CALENDAR
Ben Turner
Rough seas in the Southern Atlantic Ocean.
Controversy over the predicted collapse
Oceanographers and climate experts have said that while the study provides a worrying warning, it comes with some big uncertainties.
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"If the statistics are robust and are a correct/relevant way to describe how the actual modern AMOC behaves, and the changes relate (solely) to changes in the AMOC, then this is a very concerning result," David Thornalley, a professor of ocean and climate science at University College London, told Live Science in an email. "But there are some really big unknowns and assumptions that need investigating before we have confidence in this result."
Other climate scientists have gone so far as to pour cold water on the findings, suggesting it is "wholly unclear" that observed surface temperature evolution of AMOC can be linked to the strength of its circulation.
"While the mathematics seem expertly done, the physical foundation is extremely shaky: It rests on the assumption that the collapse shown by simplified models correctly describes reality — but we simply do not know, and there is no serious discussion of these simplified models' shortcomings,'' Jochem Marotzke, a professor of climate science and the director of the Max Planck Institute for Meteorology in Hamburg, told Live Science in an email. "Hence, while the paper might be a valid 'what if' exercise in time series analysis in a specialized journal, it falls way short of its self-proclaimed goal of estimating the evolution of the circulation solely from observations."
The researchers behind the new study say their next steps will be to update their model with data from the last three years, which should narrow their window for predicted collapse.
Ben Turner
LIVE SCIENCE
Tue, July 25, 2023
A view of hurricanes forming over the Atlantic Ocean, created by assembling images acquired on Sept. 6, 2017 by NASA's Visible Infrared Imaging Radiometer Suite (VIIRS) satellite.
A vital ocean current system that helps regulate the Northern Hemisphere's climate could collapse anytime from 2025 and unleash climate chaos, a controversial new study warns.
The Atlantic Meridional Ocean Current (AMOC), which includes the Gulf Stream, governs the climate by bringing warm, tropical waters north and cold water south.
But researchers now say the AMOC may be veering toward total breakdown between 2025 and 2095, causing temperatures to plummet, ocean ecosystems to collapse and storms to proliferate around the world. However, some scientists have cautioned that the new research comes with some big caveats.
The AMOC can exist in two stable states: a stronger, faster one that we rely upon today, and another that is much slower and weaker. Previous estimates predicted that the current would probably switch to its weaker mode sometime in the next century.
Related: Gulf Stream could be veering toward irreversible collapse, a new analysis warns
But human-caused climate change may push the AMOC to a critical tipping point sooner rather than later, researchers predicted in a new study, published Tuesday (July 25) in the journal Nature Communications.
"The expected tipping point — given that we continue business as usual with greenhouse gas emissions — is much earlier than we expected," co-author Susanne Ditlevsen, a professor of statistics and stochastic models in biology at the University of Copenhagen, told Live Science.
"It was not a result where we said: 'Oh, yeah, here we have it'. We were actually bewildered."
AMOC as a global conveyor belt
Atlantic Ocean currents work like an endless global conveyor belt moving oxygen, nutrients, carbon and heat around the globe. Warmer southerly waters, which are saltier and denser, flow north to cool and sink below waters at higher latitudes, releasing heat into the atmosphere.
Then, once it has sunk beneath the ocean, the water slowly drifts southward, heats up again, and the cycle repeats. But climate change is slowing this flow. Fresh water from melting ice sheets has made the water less dense and salty, and recent studies have shown that the current is at its weakest in more than 1,000 years.
A simplified animation of the global AMOC
The region near Greenland where the southerly waters sink (known as the subpolar gyre) borders a patch that is hitting record low temperatures, while the surrounding seas climb to all-time highs, forming an ever-expanding 'blob' of cold water.
The last time the AMOC switched modes during the most recent ice age, the climate near Greenland increased by 18 to 27 degrees Fahrenheit (10 to 15 degrees Celsius) within a decade. If it were to turn off, temperatures in Europe and North America could drop by as much as 9 F (5 C) in the same amount of time.
Direct data on the AMOC's strength has only been recorded since 2004, so to analyze changes to the current over longer timescales, the researchers turned to surface temperature readings of the subpolar gyre between the years of 1870 and 2020, a system which they argue provides a 'fingerprint' for the strength of AMOC’s circulation.
By feeding this information into a statistical model, the researchers gauged the diminishing strength and resilience of the ocean current by its growing year-on-year fluctuations.
The model's results alarmed the researchers — yet they say that checking them only reinforced their findings: The window for the system's collapse could begin as early as 2025, and it grows more likely as the 21st century continues.
"I don't consider myself very alarmist. In some sense it's not fruitful," Peter Ditlevsen, a professor of physics and climate science at the Niels Bohr Institute in Copenhagen, told Live Science. "So my result annoys me, in some sense. Because it [the window for possible collapse] is so close and so significant that we have to take immediate action now."
Tue, July 25, 2023
A view of hurricanes forming over the Atlantic Ocean, created by assembling images acquired on Sept. 6, 2017 by NASA's Visible Infrared Imaging Radiometer Suite (VIIRS) satellite.
A vital ocean current system that helps regulate the Northern Hemisphere's climate could collapse anytime from 2025 and unleash climate chaos, a controversial new study warns.
The Atlantic Meridional Ocean Current (AMOC), which includes the Gulf Stream, governs the climate by bringing warm, tropical waters north and cold water south.
But researchers now say the AMOC may be veering toward total breakdown between 2025 and 2095, causing temperatures to plummet, ocean ecosystems to collapse and storms to proliferate around the world. However, some scientists have cautioned that the new research comes with some big caveats.
The AMOC can exist in two stable states: a stronger, faster one that we rely upon today, and another that is much slower and weaker. Previous estimates predicted that the current would probably switch to its weaker mode sometime in the next century.
Related: Gulf Stream could be veering toward irreversible collapse, a new analysis warns
But human-caused climate change may push the AMOC to a critical tipping point sooner rather than later, researchers predicted in a new study, published Tuesday (July 25) in the journal Nature Communications.
"The expected tipping point — given that we continue business as usual with greenhouse gas emissions — is much earlier than we expected," co-author Susanne Ditlevsen, a professor of statistics and stochastic models in biology at the University of Copenhagen, told Live Science.
"It was not a result where we said: 'Oh, yeah, here we have it'. We were actually bewildered."
AMOC as a global conveyor belt
Atlantic Ocean currents work like an endless global conveyor belt moving oxygen, nutrients, carbon and heat around the globe. Warmer southerly waters, which are saltier and denser, flow north to cool and sink below waters at higher latitudes, releasing heat into the atmosphere.
Then, once it has sunk beneath the ocean, the water slowly drifts southward, heats up again, and the cycle repeats. But climate change is slowing this flow. Fresh water from melting ice sheets has made the water less dense and salty, and recent studies have shown that the current is at its weakest in more than 1,000 years.
A simplified animation of the global AMOC
The region near Greenland where the southerly waters sink (known as the subpolar gyre) borders a patch that is hitting record low temperatures, while the surrounding seas climb to all-time highs, forming an ever-expanding 'blob' of cold water.
The last time the AMOC switched modes during the most recent ice age, the climate near Greenland increased by 18 to 27 degrees Fahrenheit (10 to 15 degrees Celsius) within a decade. If it were to turn off, temperatures in Europe and North America could drop by as much as 9 F (5 C) in the same amount of time.
Direct data on the AMOC's strength has only been recorded since 2004, so to analyze changes to the current over longer timescales, the researchers turned to surface temperature readings of the subpolar gyre between the years of 1870 and 2020, a system which they argue provides a 'fingerprint' for the strength of AMOC’s circulation.
By feeding this information into a statistical model, the researchers gauged the diminishing strength and resilience of the ocean current by its growing year-on-year fluctuations.
The model's results alarmed the researchers — yet they say that checking them only reinforced their findings: The window for the system's collapse could begin as early as 2025, and it grows more likely as the 21st century continues.
"I don't consider myself very alarmist. In some sense it's not fruitful," Peter Ditlevsen, a professor of physics and climate science at the Niels Bohr Institute in Copenhagen, told Live Science. "So my result annoys me, in some sense. Because it [the window for possible collapse] is so close and so significant that we have to take immediate action now."
Rough seas in the Southern Atlantic Ocean.
Controversy over the predicted collapse
Oceanographers and climate experts have said that while the study provides a worrying warning, it comes with some big uncertainties.
RELATED STORIES
—Catastrophic climate 'doom loops' could start in just 15 years, new study warns
—Climate change causes a mountain peak frozen for thousands of years to collapse
—Global warming will likely cross dangerous 1.5 C threshold within 5 years, UN report warns
"If the statistics are robust and are a correct/relevant way to describe how the actual modern AMOC behaves, and the changes relate (solely) to changes in the AMOC, then this is a very concerning result," David Thornalley, a professor of ocean and climate science at University College London, told Live Science in an email. "But there are some really big unknowns and assumptions that need investigating before we have confidence in this result."
Other climate scientists have gone so far as to pour cold water on the findings, suggesting it is "wholly unclear" that observed surface temperature evolution of AMOC can be linked to the strength of its circulation.
"While the mathematics seem expertly done, the physical foundation is extremely shaky: It rests on the assumption that the collapse shown by simplified models correctly describes reality — but we simply do not know, and there is no serious discussion of these simplified models' shortcomings,'' Jochem Marotzke, a professor of climate science and the director of the Max Planck Institute for Meteorology in Hamburg, told Live Science in an email. "Hence, while the paper might be a valid 'what if' exercise in time series analysis in a specialized journal, it falls way short of its self-proclaimed goal of estimating the evolution of the circulation solely from observations."
The researchers behind the new study say their next steps will be to update their model with data from the last three years, which should narrow their window for predicted collapse.
Atlantic Ocean current could collapse soon. How you may endure dramatic weather changes.
Doyle Rice, USA TODAY
Updated Tue, July 25, 2023
Now this could be something to really worry about.
The Atlantic Meridional Overturning Circulation (AMOC) – a large system of ocean currents that carry warm water from the tropics into the North Atlantic – could collapse by the middle of the century, or possibly any time from 2025 onward, because of human-caused climate change, a study published Tuesday suggests.
Such a collapse could trigger rapid weather and climate changes in the U.S., Europe and elsewhere. If it were to happen, it could bring about an ice age in Europe and sea-level rise in cities such as Boston and New York, as well as more potent storms and hurricanes along the East Coast.
It also could lead to drastically reduced amounts of rain and snowfall across the central and western U.S., the study's authors say.
Earlier studies about the AMOC collapse drew comparisons to the scientifically inaccurate 2004 disaster movie "The Day After Tomorrow," which used such an ocean current shutdown as the premise of the film.
"We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions," the study authors write.
The AMOC collapse is one of several dangerous climate "tipping points" scientists say are possible because of climate change.
A tsunami floods New York City in the wake of a catastrophic climatic shift in a scene from the 2004 motion picture "The Day After Tomorrow." The premise of the scientifically inaccurate film mirrors that of several recent studies about the collapse of a key ocean current.
What is the AMOC?
“The Atlantic Meridional Overturning Circulation really is one of our planet’s key circulation systems,” said Niklas Boers from the Potsdam Institute for Climate Impact Research in Germany, the author of an earlier study on the topic.
The AMOC is a crucial conveyor belt for ocean water and air, which creates weather. Warm, salty water moves north from the tropics along the Gulf Stream off the U.S. East Coast to the North Atlantic, where it cools, sinks and heads south.
The faster it moves, the more water is turned over from warm surface to cool depths.
The cycle keeps northern Europe several degrees warmer than it would otherwise be and brings colder water to the coast of North America.
Studies in 2018 and 2021 have found that a collapse of the AMOC is possible at some point this century.
What's new in this study?
Using new statistical tools and ocean temperature data from the past 150 years, researchers calculated that the AMOC will stop – with 95% certainty – between 2025 and 2095. "Using new and improved statistical tools, we’ve made calculations that provide a more robust estimate of when a collapse is most likely to occur, something we had not been able to do before," said study co-author Susanne Ditlevsen, a professor at the University of Copenhagen.
The researchers' prediction is based on observations of early warning signals ocean currents exhibit as they become unstable.
The calculations contradict the message of the latest Intergovernmental Panel on Climate Change report, in which an abrupt change in the AMOC is considered "unlikely" this century.
"Our result underscores the importance of reducing global greenhouse gas emissions as soon as possible," said study co-author Peter Ditlevsen, also from the University of Copenhagen.
How could climate change cause the AMOC to collapse?
Study co-authors Peter and Susanne Ditlevsen explained to USA TODAY how the collapse of the AMOC could occur: "Greenhouse gas emissions cause global warming, which speeds up the melting of Greenland ice. The melted freshwater entering the North Atlantic can then disrupt the AMOC, potentially causing major climate disruptions.
"When the increased meltwater from Greenland enters the North Atlantic, it's freshwater, which is lighter than the salty seawater around it," the Ditlevsens said. "This excess freshwater can disrupt the normal sinking of the salty water, weakening or even shutting down the AMOC. If the AMOC collapses, it can have far-reaching effects on weather patterns and ocean currents, leading to significant climate changes."
What do others say?
Experts not involved in this study offer mixed reviews of its conclusions. Michael Mann, of the University of Pennsylvania, said, "I’m not sure the authors bring much to the table other than a fancy statistical method. History is littered with flawed predictions based on fancy statistical methods; sometimes they’re too fancy for their own good."
But Stefan Rahmstorf, a climate scientist at the Potsdam Institute for Climate Impact Research in Germany, told USA TODAY that "a single study provides limited evidence, but when multiple approaches lead to similar conclusions, this must be taken very seriously. Especially when we're talking about a risk that we really want to rule out with 99.9% certainty. The scientific evidence now is that we can't even rule out crossing a tipping point already in the next decade or two.
"There is still large uncertainty where the tipping point of the AMOC is, but the new study adds to the evidence that it is much closer than we thought just a few years ago."
The study was published Tuesday in the peer-reviewed British journal Nature Communications.
Contributing: The Associated Press; Elizabeth Weise, USA TODAY
Doyle Rice, USA TODAY
Updated Tue, July 25, 2023
Now this could be something to really worry about.
The Atlantic Meridional Overturning Circulation (AMOC) – a large system of ocean currents that carry warm water from the tropics into the North Atlantic – could collapse by the middle of the century, or possibly any time from 2025 onward, because of human-caused climate change, a study published Tuesday suggests.
Such a collapse could trigger rapid weather and climate changes in the U.S., Europe and elsewhere. If it were to happen, it could bring about an ice age in Europe and sea-level rise in cities such as Boston and New York, as well as more potent storms and hurricanes along the East Coast.
It also could lead to drastically reduced amounts of rain and snowfall across the central and western U.S., the study's authors say.
Earlier studies about the AMOC collapse drew comparisons to the scientifically inaccurate 2004 disaster movie "The Day After Tomorrow," which used such an ocean current shutdown as the premise of the film.
"We estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions," the study authors write.
The AMOC collapse is one of several dangerous climate "tipping points" scientists say are possible because of climate change.
A tsunami floods New York City in the wake of a catastrophic climatic shift in a scene from the 2004 motion picture "The Day After Tomorrow." The premise of the scientifically inaccurate film mirrors that of several recent studies about the collapse of a key ocean current.
What is the AMOC?
“The Atlantic Meridional Overturning Circulation really is one of our planet’s key circulation systems,” said Niklas Boers from the Potsdam Institute for Climate Impact Research in Germany, the author of an earlier study on the topic.
The AMOC is a crucial conveyor belt for ocean water and air, which creates weather. Warm, salty water moves north from the tropics along the Gulf Stream off the U.S. East Coast to the North Atlantic, where it cools, sinks and heads south.
The faster it moves, the more water is turned over from warm surface to cool depths.
The cycle keeps northern Europe several degrees warmer than it would otherwise be and brings colder water to the coast of North America.
Studies in 2018 and 2021 have found that a collapse of the AMOC is possible at some point this century.
What's new in this study?
Using new statistical tools and ocean temperature data from the past 150 years, researchers calculated that the AMOC will stop – with 95% certainty – between 2025 and 2095. "Using new and improved statistical tools, we’ve made calculations that provide a more robust estimate of when a collapse is most likely to occur, something we had not been able to do before," said study co-author Susanne Ditlevsen, a professor at the University of Copenhagen.
The researchers' prediction is based on observations of early warning signals ocean currents exhibit as they become unstable.
The calculations contradict the message of the latest Intergovernmental Panel on Climate Change report, in which an abrupt change in the AMOC is considered "unlikely" this century.
"Our result underscores the importance of reducing global greenhouse gas emissions as soon as possible," said study co-author Peter Ditlevsen, also from the University of Copenhagen.
How could climate change cause the AMOC to collapse?
Study co-authors Peter and Susanne Ditlevsen explained to USA TODAY how the collapse of the AMOC could occur: "Greenhouse gas emissions cause global warming, which speeds up the melting of Greenland ice. The melted freshwater entering the North Atlantic can then disrupt the AMOC, potentially causing major climate disruptions.
"When the increased meltwater from Greenland enters the North Atlantic, it's freshwater, which is lighter than the salty seawater around it," the Ditlevsens said. "This excess freshwater can disrupt the normal sinking of the salty water, weakening or even shutting down the AMOC. If the AMOC collapses, it can have far-reaching effects on weather patterns and ocean currents, leading to significant climate changes."
What do others say?
Experts not involved in this study offer mixed reviews of its conclusions. Michael Mann, of the University of Pennsylvania, said, "I’m not sure the authors bring much to the table other than a fancy statistical method. History is littered with flawed predictions based on fancy statistical methods; sometimes they’re too fancy for their own good."
But Stefan Rahmstorf, a climate scientist at the Potsdam Institute for Climate Impact Research in Germany, told USA TODAY that "a single study provides limited evidence, but when multiple approaches lead to similar conclusions, this must be taken very seriously. Especially when we're talking about a risk that we really want to rule out with 99.9% certainty. The scientific evidence now is that we can't even rule out crossing a tipping point already in the next decade or two.
"There is still large uncertainty where the tipping point of the AMOC is, but the new study adds to the evidence that it is much closer than we thought just a few years ago."
The study was published Tuesday in the peer-reviewed British journal Nature Communications.
Contributing: The Associated Press; Elizabeth Weise, USA TODAY
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