Climate
change increases exposure and bioaccumulation of pollutants in marine
organisms, posing substantial ecophysiological and ecotoxicological
risks. Here, we applied a trophodynamic ecosystem model to examine the
bioaccumulation of organic mercury (MeHg) and polychlorinated biphenyls
(PCBs) in a Northeastern Pacific marine food web under climate change.
We found largely heterogeneous sensitivity in climate-pollution impacts
between chemicals and trophic groups. Concentration of MeHg and PCBs in
top predators, including resident killer whales, is projected to be
amplified by 8 and 3%, respectively, by 2100 under a high carbon
emission scenario (Representative Concentration Pathway 8.5) relative to
a no-climate change control scenario. However, the level of
amplification increases with higher carbon emission scenario for MeHg,
but decreases for PCBs. Such idiosyncratic responses are shaped by the
differences in bioaccumulation pathways between MeHg and PCBs, and the
modifications of food web dynamics between different levels of climate
change. Climate-induced pollutant amplification in mid-trophic level
predators (Chinook salmon) are projected to be higher (~10%) than killer
whales. Overall, the predicted trophic magnification factor is ten-fold
higher in MeHg than in PCBs under high CO2 emissions. This
contribution highlights the importance of understanding the interactions
with anthropogenic organic pollutants in assessing climate risks on
marine ecosystems.