The direct and indirect effects of global emissions of black carbon (BC) on the evolution of Arctic climate have been well documented. The significance of within-Arctic emissions of BC is less certain. In light of this, an ensemble of scenarios is developed that simulates the hypothetical diversion of 75% of current and projected shipping traffic from the Suez Canal to the Northern Sea Route (NSR). This experiment shows that BC from ships results in a small change in climate forcing that does not influence the Arctic-wide trajectory of change. However, the shift in forcing from the Suez route to the NSR not only influences regional evolution of sea ice cover, but also results in regional feedbacks that in some locations amplify (e.g., Greenland Sea) and in other locations damp (e.g., Labrador Sea) the sea ice retreat under anthropogenic climate change. The primary mechanism underlying these regional effects is a shift in circulation rather than direct thermodynamic forcing. The most significant impacts are distal from the emissions sources, which is likely to have policy implications as the expansion of industrial and transportation activities into the Arctic is considered.

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