Global change and mercury cycling: challenges for implementing a global mercury treaty

The Minamata Convention aims to protect human health and the environment from anthropogenic emissions and releases of mercury. In the present study, the provisions of the Minamata Convention are examined to assess their influence on global biogeochemical cycling of Hg. Although the convention's scope covers all major categories of atmospheric emissions, the degree to which it will affect future emissions trajectories remains unclear. A box model analysis shows that future global biogeochemical cycling under projected technological provisions would result mainly in avoided increases and that estimated differences in atmospheric concentrations resulting from policies would be on the order of 1% to 2% per year. Present experience suggests that scientific knowledge is not currently sufficient to attribute causes to changes of this magnitude. Enhancements to capacity to measure the effectiveness of the Minamata Convention are suggested, including both measurement and modeling.