Collapse of AMOC ocean current may already be locked in
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- Phil Holden and Tim Lenton ran 21 computer simulations and estimate a 10-23% probability that AMOC collapse is already locked in, regardless of future action.
- Under conservative assumptions (emissions peaking 2025, Greenland adding just 54mm to sea-level rise by 2100), the modeled probability of committed collapse is 10%.
- Under a higher Greenland melt scenario projecting 274mm of sea-level rise by 2100, the probability that collapse is already committed rises to 23%.
- Tim Lenton at the University of Exeter says if emissions don't peak until 2100, the model puts the probability of AMOC collapse at 80%.
- Even when collapse is committed, the simulations show an average 84-year delay before it actually occurs, with the earliest collapse happening around 2060.
- Each additional decade of unabated emissions after the point of commitment shortens the actual collapse timeline — from 84 years on average to 57 years.
- Jonathan Baker at the UK Met Office cautioned the model deliberately uses a low-resolution 5° grid, meaning risk estimates could shift with higher-resolution modeling.
Why it matters: With a 10-23% probability researchers say humanity may already be locked into AMOC collapse regardless of future action, the urgency of reaching net zero earlier intensifies — delaying the peak of emissions until 2100 pushes modeled collapse odds to 80%. Even under the best-case scenario, a collapse committed today would arrive decades from now (earliest ~2060, average 84-year lag), leaving European climate stability, African and Asian monsoon systems, and North Atlantic ecosystems with a narrowing window for adaptation and mitigation.
