Right now, the Arctic Ocean is still too icy and treacherous for open-water ships to traverse with any regularity. The Northwest Passage is only navigable during the summer months once every seven years or so. Too unreliable for commercial shipping.

But that will soon change. As the planet keeps warming, the Arctic's summer sea ice is vanishing at a stunning pace. That rapid melt is expected to have all sorts of sweeping impacts, from speeding up climate change to wreaking havoc on weather patterns. On the flip side, the loss of sea ice could also open up some potentially lucrative new trade routes between the Atlantic and Pacific Oceans.

A new study in the Proceedings of the National Academies of Science, led by UCLA geographer Laurence Smith, looks at how the Arctic will change under even modest levels of global warming. Through computer simulations, the researchers found that open-water vessels will be able to, in theory, cross the Northwest Passage and North Sea Route regularly in the summer by 2050 without icebreakers. And icebreaker ships may be able to ram right through the North Pole:

The blue lines show the fastest routes available for common open-water ships during the summer, while the red lines show routes available for Polar Class 6 ships with moderate icebreaker capacity. By 2040-2059, there are many more routes.

The change here is quite striking. Right now, no commercial shipping goes through the Northwest Passage that hugs northern Canada. Yet by mid-century, those routes could potentially be clear for open-water vessels every other summer. Likewise, the Northern Sea Route that hugs Russia is projected to be open in late summer 90 percent of the time, up from 40 percent today.

That could transform shipping, at least during those summer months. As a news release from UCLA points out, it's 40 percent quicker to ship goods from Rotterdam, Netherlands to Yokohama, Japan along the Northern Sea Route than it is to take conventional shipping routes through the Suez Canal. That's still far from a given—it depends on how the economics evolve, since Arctic shipping will remain risky. But global warming will remove a key physical barrier here.

(Note that these routes would only be accessible during the summer — even if the planet gets a lot warmer, the Arctic will still be too icy and forbidding during the winter months, when the sea ice recovers.)

The UCLA write-up for the study talks up the unexpectedness of this finding. "Nobody's ever talked about shipping over the top of the North Pole," Smith says. "This is an entirely unexpected possibility." But the paper itself also notes some of the potential problems that could emerge. To date, countries have few rules in place for safeguarding the Arctic environment or for rescuing stranded commercial ships. It's rarely been an issue before.

One last note: There's also the possibility that this paper might even be understating the situation and the Arctic summer sea ice could wither even faster than climate models project. In 2012, the extent of Arctic sea ice hit a record low in August and computer models have, to date, underestimated the pace of sea-ice decline.

Further reading:

--Arctic sea ice hit a record low in 2012. Here's a primer on why that matters, from the speeding up climate change to the possibility that the Arctic melt will bring weirder weather to North America and Europe.

--When will the Arctic be ice-free in the summer? Maybe 4 years. Or 40. A look at how early computer models woefully underestimated the pace of change up north.