Understanding climate change impacts on transportation systems is particularly critical in northern latitudes, where subzero. temperatures restrict shipping, but enable passage of ground vehicles over frozen soil and water surfaces. Although the major transport challenges related to climate warming are understood, so far there have been no quantitative projections of Arctic transport system change. Here we present a new modelling framework to quantify changing access to oceans and landscapes northward of 40 degrees N by mid-century. The analysis integrates climate and sea-ice model scenarios(1,2) with topography, hydrography, land cover, transportation infrastructure and human settlements. Declining sea-ice concentration and thickness suggest faster travel and improved access to existing (+5 to +28%) and theoretical (+11 to +37%) offshore exclusive economic zones of Canada, Greenland, Russia and the US. The Northern Sea Route, Arctic Bridge and North Pole routes are projected to become fully accessible from July-September, averaging similar to 11, 15 and 16 days to traverse, respectively, whereas the Northwest Passage will not. All eight Arctic states are projected to suffer steep declines (-11 to -82%) in accessibility inland, driven by lost potential for winter road construction caused by milder winters and deeper snow accumulation.
