Linking Science to Global Environmental Action: Lessons from Mercury Pollution

Noelle Selin (Professor in the Institute for Data, Systems and Society and the Department of Earth, Atmospheric and Planetary Sciences, and the Director of MIT’s Center for Sustainability Science and Strategy)

Scientific research can be critical to identifying global environmental problems, understanding them, and implementing potential solutions. How can science contribute to evaluating the effectiveness of global environmental policies? In this talk, I discuss how scientists and policy-makers are addressing the question of policy effectiveness, with examples from the case of mercury pollution. In October 2013, a global treaty called the Minamata Convention on Mercury was signed, aiming to protect human health and the environment from anthropogenic mercury. Measurements and models can contribute to identifying and attributing changes in environmental concentrations of mercury, but doing so is tricky: mercury cycles between the land, atmosphere, and ocean, and current levels are driven not only by contemporary emissions but also by the legacy of historical uses. While uses of mercury in products and processes are being phased out, and emissions controls are being implemented worldwide for major sources, the most recent inventories available suggest that mercury emissions increased globally in the 2010s. I will present results from a combination of data analysis and modeling that suggests that these pessimistic estimates are probably wrong -- contemporary anthropogenic emissions have most likely declined. In follow up work, we have developed ways to leverage limited data to better constrain emissions, taking advantage of signals from its variability over time. I conclude by discussing lessons learned for evaluating the effectiveness of global environmental treaties in general.