Global scenarios of anthropogenic mercury emissions

Abstract

Abstract. Anthropogenic mercury (Hg) emissions to the atmosphere are a long-lived hazard to human and environmental health. The UN Minamata Convention on Mercury is seeking to lower anthropogenic mercury emissions through a mix of policies from banning Hg uses and trade, to reducing unintentional Hg releases from different activities. In addition to independent Hg policy, greenhouse gas, particulate matter (PM) and SO₂ reduction policies may also lower Hg emissions as a co-benefit. This study uses the Greenhouse Gas – Air Pollution Interactions and Synergies (GAINS) model to examine the effect of different clean air and climate policy on future global Hg emissions. The Baseline scenario assumes current energy use and Hg emissions, as well as current legislation for clean air, mercury and climate policy. In addition, we explore the impact of the Minamata Convention, co-benefits of climate policies and of stringent air pollution policies, as well as a maximum feasible reduction scenario for Hg (Hg-MFR). Hg emission projections until 2050 show noticeable reductions in combustion sectors for all scenarios, due to a decrease in global fossil fuels and traditional biomass use, leading to emission reductions of 33 % (Baseline) up to 90 % when combining stringent climate and Hg-MFR. Cement and non-ferrous metal emissions increase in all activity scenarios with current air pollution policy, but can be reduced by up to 72 % and 46 % respectively in 2050 with stringent Hg-specific measures. Other emissions (including waste) are a large source of uncertainty in this study, and projections range between a 22 % increase and 54 % decrease in 2050 depending on both climate and clean air policy. The largest absolute reduction potential for Hg abatement, but also the largest uncertainties of absolute emissions lie in the in small-scale and artisanal gold production, where Hg-specific abatement measures could eliminate annual Hg emissions in the range of 601–1371 t (95 % confidence interval). 90 % of the Hg emissions in GAINS are covered by the Minamata Convention. Overall, the findings emphasize the necessity of implementing targeted Hg control policies in addition to stringent climate, PM and SO₂ policies to achieve significant reductions in Hg emissions.