Local and remote contributions to Arctic warming

I investigate the relative impact of local and remote radiative forcing by tropospheric aerosols and ozone on Arctic climate using GISS climate model simulations. During boreal summer, Arctic climate is well-correlated with either the global or Arctic forcing. During other seasons, however, large-scale dynamics strongly influence the Arctic, so that the surface temperature response follows the global or Northern Hemisphere extratropical forcing much more closely. The decoupling is so strong that Arctic surface temperature trends often show the opposite sign to the local forcing. The analysis also demonstrates that ozone and aerosols affect Arctic climate more strongly per unit global forcing than well-mixed greenhouse gases, typically 2.5– 5 times in non-summer seasons, making them powerful levers for influencing Arctic climate. However, controlling atmospheric burdens of climate-altering pollutants outside the polar region appears to be at least as important as controlling them within for mitigation of Arctic warming.