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Rapidly melting sea ice will open up shipping lanes across the Arctic, potentially making the Northwest Passage (left) and North Pole (center) navigable during the summer. Image via PNAS/Smith and Stephenson

Rapidly melting ice has already remade shipping possibilities in the Arctic. Over the past decade, commercial use of the Northern Sea Route (the blue shipping lane along the northern coast of Russia in the map above) during late summer has become commonplace, dramatically shortening the journey from Europe to the Far East.

If present trends continue, though, the options for shipping goods across the Arctic will expand even more. According to a paper published today in the Proceedings of the National Academy of Sciences, by 2040, the legendary Northwest Passage (the shipping lane on the left side of the map, along the cost of Canada and Alaska) could be accessible during some summers to normal oceangoing ships without specially reinforced ice-breaking hulls. Most surprisingly, at times, reinforced polar icebreakers might even be able to plow straight across the North Pole, making the shortest possible journey across the Arctic.

All this is due to the fact that, over the past two decades, temperatures have risen even faster in the Arctic than the planet as a whole. Although the polar ice pack grows each winter and shrinks each summer, the overall trend has been a decrease in total ice cover, as seen in the video below. In the future, this will open up a window for reinforced ships to break through weaker ice, and for normal ships to cruise through ice-free corridors.

The new study, by Laurence Smith and Scott Stephenson of UCLA, uses existing climate models to examine how this trend will change Arctic shipping for the years 2040 to 2059. They looked at theoretical ice conditions under a pair of climate scenarios from the UN’s Intergovernmental Panel on Climate Change’s most recent report, one that assumed a medium-low level of greenhouse gas emissions going forward, and another that assumed a high level. They also explored the navigational possibilities for two different types of ships: Polar Class 6 ice-breaking ships and normal oceangoing vessels.

Their analysis found that in both scenarios, the Northern Sea Route—already navigable for reinforced vessels in late summer most years—will become wider, opening up for a greater number of months each summer and allowing for a greater geographical diversity in routes. The wider lane will enable ships to take routes further away from the Russian coast and closer to the North Pole, shortening the journey over the top of our planet, and will allow unreinforced ships to travel through without an ice-breaking escort.

Currently, the Northwest Passage is inaccessible for normal vessels, and has only been transited a handful of times by reinforced ice-breaking ships. Under both of the scenarios in the model, though, it becomes navigable to Polar Class 6 ships every summer. At times, it could even be open to unreinforced vessels as well—the study shows that, when multiple simulations were run in both medium-low and high levels of greenhouse gas emissions, open sailing was possible for 50 to 60 percent of the years studied.

Finally, the straight shot over the North Pole—a route that would currently take would-be captains through a sheet of ice as much as 65 feet thick in areas—could also become possible for Polar Class 6 ships in both scenarios, at least in warmer years. “Nobody’s ever talked about shipping over the top of the North Pole,” Smith said in a press statement. “This is an entirely unexpected possibility.”

The most striking part of the study might be that these dramatic changes occurred in simulations assuming both medium-low and high levels of emissions, and that the time period studied isn’t all that far away, beginning just 27 years from the present. “No matter which carbon emission scenario is considered, by mid-century we will have passed a crucial tipping point—sufficiently thin sea ice—enabling moderately capable icebreakers to go where they please,” Smith said.