Climate models show varied predictions for the weakening of the Atlantic meridional overturning circulation (AMOC) this century. Researchers, including Laure Zanna and CliMA members, reduced this uncertainty by linking AMOC strength to the meridional density difference and overturning depth. They found that models with a deeper present-day overturning predict greater weakening due to less stratified North Atlantic waters. Using observational data, they estimate a modest AMOC weakening of about 4 Sv by century’s end, regardless of emissions. The study highlights that inaccuracies in current ocean stratification models lead to exaggerated predictions of AMOC weakening.