Full Breakdown
Study Projects Up to 50 % Slowdown of Atlantic Meridional Overturning Circulation by 2100
4/25/2026, 11:53:02 AM
Core Findings: Potential 50 % Reduction in AMOC Strength
A recent analysis using a novel methodology estimates that the Atlantic Meridional Overturning Circulation (AMOC) could weaken by as much as 50 % (± 8 %) by the end of the century. The authors describe the result as “real” and note that the associated uncertainty is considerably lower than in earlier work, which had projected a 30 % slowdown with a 37 % error margin.
Scientific Context and Mechanisms
The AMOC transports warm, salty water northward in the Atlantic, where it cools, becomes denser, and sinks, driving a global conveyor belt that moves heat and influences regional climates. Rising sea-surface temperatures and freshening of Atlantic waters—partly from Greenland ice-sheet melt—reduce surface water density, inhibiting sinking and thus weakening the circulation.
Key Researchers and Their Views
- Wei Liu, associate professor of climate change at the University of California, Riverside, notes that observed trends may reflect either a long-term decline or natural variability.
- Kent Moore, professor of atmospheric physics at the University of Toronto, emphasizes the complexity of climate models and warns that “if you get anything wrong then you may not get a good prediction.” He also highlights the new study’s tighter uncertainty bounds.
- Stefan Rahmstorf, co-head of research at the Potsdam Institute for Climate Impact Research, stresses that the low-likelihood, high-impact risk of a major slowdown is now “gone,” given the latest evidence.
Quantitative Projections and Regional Impacts
- Earlier assessments: 30 % slowdown by 2100 (± 37 % error).
- New study: up to 50 % slowdown (± 8 %).
- East-coast Canada sea-level rise: ~25 cm.
- Global sea-level rise potential: about 1 m if the AMOC weakens substantially.
- European winter temperatures could fall to –20 °C in some regions, while summers remain warm.
- Projected shifts include a more southerly tropical rain belt, increased drying in Europe, and amplified temperature contrasts that could disrupt agriculture (e.g., early blossoms followed by sudden cold snaps).
Divergent Model Estimates and Uncertainties
Scientists acknowledge that climate models differ in how they represent ocean-atmosphere-ice interactions. Some studies still predict a possible shutdown by century’s end, while others view a complete collapse as unlikely. The role of Greenland melt is debated; Rahmstorf describes the common perception that melt is the primary driver as a “misconception,” noting its effect is modest relative to other factors.
Broader Climate Implications
Even a partial slowdown would alter weather patterns, raise regional sea levels, and potentially trigger geopolitical shifts as populations seek more temperate locales. The AMOC’s energy transport—estimated at 100 times human energy consumption—means that any weakening could amplify extreme events worldwide.
Verbatim Quotes
- “It has been argued whether the signal could represent long-term decline change, or maybe it's only part of the variability,” — Wei Liu, University of California, Riverside
- “Climate models are complicated things,” — Kent Moore, University of Toronto
- “The models that they use, they come up with a much more — not to say better result — but essentially a result where the uncertainty is much lower,” — Kent Moore, University of Toronto
- “I've been working on this for 35 years, on this AMOC stability problem. And we always thought the consequences would be very severe,” — Stefan Rahmstorf, Potsdam Institute for Climate Impact Research
- “If the AMOC weakens, the predictions are that sea level will rise along the east coast of Canada, by maybe 25 centimetres," he said.” — Kent Moore, University of Toronto
- “I'm not going to experience it, but I'm worried about my grandchildren," Moore said.” — Kent Moore, University of Toronto
What’s Next
Researchers plan to expand ocean-monitoring networks and refine model representations of freshwater influx and sea-ice feedbacks. Ongoing satellite and buoy observations will test the new slowdown projections as the century progresses.
