The secretariat of the Minamata Convention co-organizes with the International Conference on Mercury as a Global Pollutant (ICMGP) a series of Minamata Online sessions, related to the five ICMGP synthesis papers to be published in early 2023. In this session, convened with the synthesis paper authors, the panellists will share the best available scientific knowledge of how mercury cycling in the Southern Hemisphere and tropics differs from the better-studied Northern Hemisphere. The session will first cover natural hemispheric differences in mercury cycling then turn to hemispheric differences in the response of mercury to anthropogenic perturbations, before finishing with a discussion of the most critical future research needs.