Early-onset of Atlantic Meridional Overturning Circulation weakening in response to atmospheric CO2 concentration

• Published in: npj Climate and Atmospheric Science
• Main Authors: Dima, Mihai, Nichita, Denis R., Lohmann, Gerrit, Ionita, Monica, Voiculescu, Mirela
• Other Authors: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Alfred Wegener Institute for Polar and Marine Research, "Dunarea de Jos" University
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Atmospheric Science; Environmental Chemistry; Global and Planetary Change; North Atlantic
• Online Access: http://dx.doi.org/10.1038/s41612-021-00182-x; http://www.nature.com/articles/s41612-021-00182-x.pdf; http://www.nature.com/articles/s41612-021-00182-x

Abstract The Atlantic Meridional Overturning Circulation (AMOC), a tipping component of the climate system, is projected to slowdown during the 21st century in response to increased atmospheric CO 2 concentration. The rate and start of the weakening are associated with relatively large uncertainties. Observed sea surface temperature-based reconstructions indicate that AMOC has been weakening since the mid-20th century, but its forcing factors are not fully understood. Here we provide dynamical observational evidence that the increasing atmospheric CO 2 concentration affects the North Atlantic heat fluxes and precipitation rate, and weakens AMOC, consistent with numerical simulations. The inferred weakening, starting in the late 19th century, earlier than previously suggested, is estimated at 3.7 ± 1.0 Sv over the 1854–2016 period, which is larger than it is shown in numerical simulations (1.4 ± 1.4 Sv).