A weakening of the Atlantic Meridional Overturning Circulation (AMOC) has been found to be globally beneficial by economic assessments. This result emerges because AMOC weakening would cool the Northern Hemisphere, thereby reducing expected climate damages and decreasing estimates of the global social cost of carbon dioxide (SCC). There are, however, many other impacts of AMOC weakening that are not yet taken into account. Here, we add a second impact channel by quantifying the effects of AMOC weakening on ocean carbon uptake, using biogeochemically-only coupled freshwater hosing simulations in the Max Planck Institute Earth System Model. Our simulations reveal an approximately linear relationship between AMOC strength and carbon uptake reductions, constituting a carbon cycle feedback that leads to higher atmospheric CO