Projections of global mercury emissions in 2050.

Global Hg emissions are presented for the year 2050 under a variety of assumptions about socioeconomic and technology development. We find it likely that Hg emissions will increase in the future. The range of 2050 global Hg emissions is projected to be 2390-4860 Mg, compared to 2006 levels of 2480 Mg, reflecting a change of -4% to +96%. The main driving force for increased emissions is the expansion of coal-fired electricity generation in the developing world, particularly Asia. Our ability to arrest the growth in Hg emissions is limited by the relatively low Hg removal efficiency of the current generation of emission control technologies for coal-fired power plants (flue-gas desulfurization). Large-scale deployment of advanced Hg sorbent technologies, such as Activated Carbon Injection, offers the promise of lowering the 2050 emissions range to 1670-3480 Mg, but these technologies are not yet in commercial use. The share of elemental Hg in total emissions will decline from today's levels of approximately 65% to approximately 50-55% by 2050, while the share of divalent Hg will increase. This signals a shift from long-range transport of elemental Hg to local deposition of Hg compounds-though emissions of both species could increase under the worst case.