157 - Assessing Impacts of Climate Change on Mercury Dynamics and Human Exposure Using a Global Model

With the implementation of the Minamata Convention on Mercury, it is expected that anthropogenic mercury emissions will be reduced. Aside from this emission reduction, climate change may also affect future mercury dynamics. This study was aimed at examining impacts of climate change on mercury dynamics and human exposure using our global model, FATE-Hg. We used outputs of earth system models (ESMs) obtained from public datasets of World Climate Research Programme (WCRP), Coupled Model Intercomparison Project phase 6 (CMIP6), to force FATE-Hg. We performed, past and future, long-term (1200-2100) simulations under four climate change scenarios (ssp1-2.6, ssp2-4.5, ssp3-7.0, and ssp5-8.5). For ESMs, we adopted MIROC-ES2L for physical data, UKESM1-0-LL for carbon cycle and biological data, and MRI-EMS2-0 to obtain atmospheric reactant concentrations. The results showed that global contents of total mercury (THg) in the atmosphere and the ocean have increased since 2010; even we assumed constant emission for the year 2010 throughout the future simulation period. This may be explained by the past mercury emissions and the inertia of the system. The impact of climate change on THg contents became evident in the lower troposphere and the upper ocean in around 2050 and later, with larger contents in ssp5-8.5 (Fossil-fueled Development) and smaller contents in ssp1-2.6 (Sustainability). Furthermore, we calculated human exposure to methylated mercury (MeHg) via seafood consumption, which is the main cause for IQ reduction in newborns, eventually leading to economic losses. For this calculation, we used simulated MeHg concentrations in marine particle organic matter and FAO global statistical data for fishery. In contrast to the results for THg contents, we could not find any impacts of climate change on both the global average of MeHg intake and the global economic loss.