Visualize the summer of 2050, and you might see an Alaskan Arctic bustling with maritime activity.
Commercial ships from Japan and the United States will be steaming through the Bering Strait toward Europe on an 11-day, 3,200-mile Northern Sea Route that remains open to ice-strengthened vessels all season. Other vessels plow due North, across the geographic North Pole itself, bound for Rotterdam on a 16-day, 4,300-mile journey that would have been seen as absurd science fiction only a century earlier. Barges and tenders will regularly visit mines, ports and stations.
But come winter, the picture shifts dramatically.
The ocean refreezes. Some shipping might continue to bust through the relatively meager floes of new ice when possible. Yet winter ice-road travel across Alaska's tundra -- a mainstay of Prudhoe Bay oil work since wind-burned roughnecks drilled the Discovery Well five decades ago -- has been sharply curtailed.
With higher overall temperatures, sometimes complicated by insulating snow, tundra and lake will take longer to freeze thick enough to support vehicles 2.2 tons and larger, with the construction of fresh ice roads becoming much more difficult. The fickle window of winter travel will dwindle. By mid-century, the warming trend might have eliminated 50,000 square miles from Alaska's dark-season transportation network: a 30 percent reduction from the present.
Across the entire Arctic, it's the same story. Including vast acreage in northern Russia and Canada, an additional 468,000 square miles of the inland Far North could now be inaccessible to heavy trucks. The ground just won't be freezing as hard or as deep as it used to.