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Multiple Studies Point to Mid-Century Collapse Window
Recent research suggests that collapse of the Atlantic Meridional Overturning Circulation (AMOC) could occur between 2025 and 2095, with the most likely timing around 2057. Five different studies have pointed to the possibility of collapse happening within this century or even before mid-century. 44 leading climate scientists from 15 countries have written an open letter warning that the risks of AMOC collapse have been “greatly underestimated”. Analysis of data indicates that the present-day AMOC is on a trajectory toward tipping. Scientists now assess that there’s probably greater than a 50% risk of passing the tipping point this century. These aren’t just abstract warnings—they’re based on real-time monitoring and advanced modeling that’s only become possible in recent years.
Europe Faces Unprecedented Cooling Despite Global Warming
An AMOC collapse would cause substantial cooling over Europe, with London potentially seeing winter cold extremes of minus 2.2°F and Oslo experiencing temperatures as low as minus 55°F. In a modeled world with AMOC collapse, one-in-10 winters in London could see extremes approaching -20°C, while Oslo could plummet to around -48°C. Climate experts describe the extreme winters as “like living in an ice age,” creating a climate where “it would be like coming out of the freezer into a frying pan of summer heatwaves”. Parts of the Netherlands and UK would experience “spectacular cold extremes” down to -20°C or lower, with societal structures and infrastructure not built for such conditions. Some European cities could see temperature drops of 5 to 15°C in just a few decades, with February temperatures in Bergen, Norway becoming 3.5°C colder every decade. The cooling would be so rapid and severe that it would completely override the warming effects of climate change across much of northern Europe.
Greenland Ice Melt Accelerates Ocean Disruption
Since 2002, Greenland has lost 5,900 billion tonnes of ice—equivalent to covering the entire state of New South Wales in ice 8 meters thick. This fresh meltwater flowing into the subarctic ocean is lighter than salty seawater, reducing the amount of water that descends to ocean depths and weakening the Gulf Stream. The Greenland ice sheet will continue melting over the coming century, and if this meltwater is included in climate projections, the overturning circulation could be 30% weaker by 2040—20 years earlier than initially projected. Current climate models don’t even account for this critical factor in AMOC’s demise, as massive amounts of fresh water slough off the ice sheet and disrupt one of circulation’s driving forces: salt. Scientists have identified meltwater from Greenland and Arctic glaciers as the “missing piece in the climate puzzle” that makes oceanic circulation slowdown match reality when factored into simulations.
Global Food Security Faces Massive Disruption
AMOC shutdown would cause a shift in tropical rainfall patterns, making monsoons unreliable in West Africa and South Asia, while huge swaths of Europe and Russia would plunge into drought, with up to half the world’s viable corn and wheat growing areas drying out. In Britain alone, land suitable for arable farming would drop from 32% to just 7% under AMOC collapse, causing “widespread cessation of crop-growing farming” and leaving the country cooler, drier, and unsuitable for many crops. The resulting changes would directly impact agriculture, food prices, transportation, construction, disease patterns, immigration, and political stability. Scientists point to the connection between AMOC and precipitation over the Sahel region, which has experienced seven political coups in the past three years—climate variability being directly linked to economic impacts and political instability. The main agricultural problem would be reduced rainfall, and while irrigation could be used, the water requirements and costs “appear to be prohibitive”. This would create what experts describe as a combined food and water security crisis on a global scale.
Marine Ecosystems Face Catastrophic Collapse
Weakening of the AMOC would reduce primary production in the North Atlantic, while severe weakening could lead to Ice Age-like cooling with sea-ice expansion and mass glacier formation within a century. The North Atlantic is a hotspot for ocean carbon uptake due to the AMOC, and its collapse would strongly reduce COâ‚‚ uptake that occurs there, though scientists note they don’t currently see such trends in monitoring data. Like a sudden drop in blood pressure, weakening or shutdown of the AMOC could cut off vast swaths of the ocean from vital supplies of heat and nutrients. Even slight AMOC slowdown can affect the timing of the Indian monsoon and lead to shifts in tropical rain patterns, resulting in droughts over the African Sahel. Overturning sites are associated with intense exchanges of heat, dissolved oxygen, carbon and other nutrients, making them crucial for ocean ecosystems and the ocean’s function as a carbon sink. The disruption would cascade through marine food webs, potentially causing fishery collapses that millions of people depend on for protein and livelihoods.
Sea Level Rise Accelerates Along Coastlines
The weakening of AMOC results in dynamic sea-level rise in the Atlantic Ocean, with some coastal regions experiencing more than 70 cm of rise. Weakening of the AMOC would accelerate sea level rise around North America. Sea levels would rise up to a meter in some places, particularly affecting the East Coast of the United States. Sea level changes due to thermal expansion and ocean dynamics could potentially aggravate problems near the northeast North America coast and islands in the western Pacific region. If the circulation collapsed, consequences on both sides of the Atlantic Ocean would be immense, including large temperature changes and a spike in weather-related disasters. The combination of thermal expansion from warming waters and changes in ocean circulation patterns creates a double threat for coastal communities. This isn’t just about gradual rise—it’s about rapid changes that could overwhelm existing coastal defenses and infrastructure.
Warning Signs Already Visible in Ocean Data
Analysis of sea surface temperature data indicates the AMOC has weakened by 3 ± 1 Sverdrups since about 1950, and proxy records suggest it’s currently in its weakest state in over a millennium. Since the 1950s, AMOC’s circulation strength has decreased by 10 to 15 percent, though as long as water hasn’t freshened too much from glacier melt, the conveyor belt will “keep on cranking”. Scientists have found that once there’s enough fresh water input, the slow decline that’s been happening will “drop off like a cliff,” causing AMOC to essentially grind to a halt. Early warning signals including increased variance and autocorrelation—indicating loss of resilience and critical slowing down—have recently been reported for the AMOC. Researchers have developed a physics-based early warning signal of AMOC tipping, and analysis indicates that the present-day AMOC is “on route to tipping”. These aren’t theoretical future risks—the system is already showing measurable signs of instability that scientists can detect in real-time monitoring data.
Historical Precedent Shows Rapid Climate Shifts
Around the end of the last ice age, mass melting of ice sheets inundated the Northern Atlantic with freshwater, changing water density and making it difficult for water to sink, resulting in massive cooling in the Northern Hemisphere and warming in the south within just decades. The last Atlantic Current halt occurred about 12,900 years ago when melting of giant frozen Lake Agassiz caused fresh water to spill into the sea, followed by 1,300 years of freezing. The thermohaline circulation has operated in its present mode since the last ice age, and abrupt climate jumps between present and collapsed states have been observed 25 times in connection with ice age climate. Dansgaard-Oeschger events show rapid warming of 8-15°C that occurred in Greenland over several decades, with equivalent cooling over the Southern Ocean, consistent with strengthened AMOC transporting heat between hemispheres. One well-known event called the Younger Dryas happened about 12,700 years ago and caused temperatures to cool about 5°C in the region. These historical examples demonstrate that ocean circulation changes can trigger climate shifts far more dramatic and rapid than gradual global warming.
Conflicting Studies Create Uncertainty About Timing
A February 2025 study published in Nature concluded that AMOC is resilient to extreme greenhouse gas and freshwater forcings across 34 climate models, with Southern Ocean upwelling sustaining a weakened AMOC and preventing complete collapse. However, scientists note this study still supports the conclusion that AMOC is expected to severely weaken under extreme climate change, and the results “should certainly not be interpreted as showing that AMOC is a resilient system”. One of the authors confirmed that this new paper “does not contradict earlier modeling studies about future AMOC changes,” explaining “It’s the same models, showing the same things – just the wording is different”. Another study suggests AMOC will weaken by 18-43% by the end of the 21st century, representing “some weakening” but “not the near-collapse that more extreme climate model projections suggest”. Some scientists believe the likelihood of AMOC collapse before the end of the century is “pretty small” and “most likely the weakening will be modest”. The scientific community remains divided on exact timing, but there’s broad consensus that significant weakening is already underway and will continue.
Tipping Point Mechanics Explain Sudden Shifts
AMOC is considered a “tipping element” that can flip abruptly between two fundamentally different states—like someone leaning back in a chair who can return to stability until they tilt past a threshold and topple over into a new stable state. Research shows AMOC could exist in either a strong state or collapse to a much weaker state without recovering unless increased warming and freshening is reduced, with the possibility it’s a bistable system that could suddenly collapse being debated for decades. Climate models show hysteresis behavior where changing freshwater input into the Northern Atlantic makes AMOC bifurcate through saddle-node bifurcations. Early warning signals show that the minimum freshwater transport occurs 25 years before the actual AMOC tipping event, with variability increasing as the system loses resilience when approaching the critical threshold. Scientists emphasize that even “medium confidence” in AMOC not collapsing “is not reassuring and clearly leaves open the possibility” of collapse this century, with catastrophic impacts “impacting the entire world for centuries to come”. Understanding these mechanics helps explain why the transition could happen much faster than the gradual changes leading up to it.
What would happen if this vast oceanic conveyor belt suddenly ground to a halt? The evidence suggests we may find out sooner than we’d like to imagine.
