Global warming opening new shipping routes in Arctic Ocean

unreinforced hulls, which make up the lion’s share of the world’s commercial fleet.

Today, the Northwest Passage is theoretically navigable only one out of seven years, on average, making it too unreliable to be a viable option for commercial shippers, the researchers said. By mid-century, however, sea ice will melt in September to the point that it is accessible every other year, on average. Choosing whether to ship through the passage “will become a coin toss,” Smith said.

The predictions, however, do not foresee access beyond late summer. “This will never be a year-round operation,” Smith stressed.

Smith is an authority on the ways in which climate change is affecting the Arctic, where average temperatures have risen faster than the global average since the mid-1980s. He has quantified the disappearance of more than 1,000 Arctic lakes. He also is the author of The World in 2050: Four Forces Shaping Civilization’s Northern Future, a 2010 book that looks at new economic opportunities, as well as environmental degradation, taking shape in the northern quarter of the globe. With Stephenson, Smith has calculated the toll global warming will take on Arctic ice roads and the communities and businesses that depend on them.

The release notes that for centuries, the Arctic Ocean has captured the imagination of explorers because of the possibility it offers for traveling between the Pacific and the Atlantic oceans through the Bering Strait. Until recently, however, sea ice has blocked access to the potential shortcut between Asia and North America or Europe. In the past two years, the ice has begun to melt in late summer to such an extent that even ordinary seagoing vessels, albeit with escorts, have been able to enter its frigid waters. In summer 2012, a total of forty-six voyages successfully crossed the Northern Sea Route.

To arrive at their predictions, Smith and Stephenson studied these emerging shipping routes and the degree of ice melt that has made them possible. They then took the results from seven respected forecasts for the sea ice cover in the Arctic and averaged predictions for the extent of the Arctic ice sheet in September, historically the month when the ocean has the least amount of ice coverage, for every year between 2040 and 2059.

The researchers factored in two scenarios for climate change: one that assumed a 25 percent increase in global carbon emissions, which is generally expected to produce a medium-low increase in