5–10 years after the temperature rise ceases, but it does not come close to collapse, and recovers its strength after about 150 years. In 2021, the IPCC Sixth Assessment Report again assessed that the AMOC is very likely to decline within the 21st century, and expressed high confidence that changes to it would be reversible within centuries if the warming was reversed. Unlike the Fifth Assessment Report, it had only expressed medium confidence rather than high confidence in AMOC avoiding a collapse before the end of the century. This reduction in confidence was likely influenced by several review studies drawing attention to the circulation stability bias within general circulation models, as well as simplified ocean modelling studies suggesting that the AMOC may be more vulnerable to abrupt change than what the larger-scale models suggest. In 2022, a study performed modelling experiments with three climate models participating in Aerosol and Chemistry Model Intercomparison Project, and it found that very aggressive mitigation of air pollution like particulates and ground-level ozone could weaken AMOC circulation by 10% by the end of the century if it happened on its own, due to the reduction in climate-cooling stratospheric sulfur aerosols. The authors recommended pairing air pollution mitigation with the mitigation of methane emissions in order to avoid this outcome, as both methane (a strong warming agent) and sulfate aerosols (a cooling agent) are similarly short-lived in the atmosphere, and a simultaneous reduction of both would cancel out their effects. In 2022, an extensive assessment of all potential climate tipping points identified 16 plausible climate tipping points, including a collapse of the AMOC. It suggested that a collapse would most likely be triggered by 4 degrees Celsius of global warming, but that there's enough uncertainty to suggest it could be triggered at warming levels as low as 1.4 degrees, or as high as 8 degrees. Likewise, it estimates that once AMOC collapse is triggered, it would most likely take place over 50 years, but the entire range is between 15 and 300 years. Finally, it concludes that this collapse would lower global temperatures by around 0.5 degrees Celsius, while regional temperatures in Europe would go down by between 4 and 10 degrees Celsius. That assessment also treated the collapse of the Northern Subpolar Gyre as a potential separate tipping point, which could occur at between 1.1 degrees and 3.8 degrees of warming (although this is only