The storied Northwest Passage is open — its so-called “southerly route,” anyway. Such is the latest assessment from the National Snow and Ice Data Center, which suggests that the passage famously discovered by the explorer Roald Amundsen in the early 1900s, connecting Baffin Bay to the Beaufort Sea via straits within the Canadian Arctic archipelago, may be navigable at the moment (though the center also urges contacting authorities before reaching this conclusion).

The Passage — which is really a collection of multiple possible sea routes through the icy islands — has been drawing more and more attention lately. President Obama’s trip to the Alaskan Arctic, and his call for the U.S. to beef up its tiny fleet of icebreakers, has focused attention on predictions that the region will see much more shipping and tourism as sea ice steadily declines. And if you want to boost shipping, being able to get from the U.S. west coast to its east coast (or vice versa) without having to sail down to the Panama Canal would certainly be a boon.

But whether or not a part of the passage is currently navigable — at a time when Arctic sea ice is nearing its annual low — new research casts doubt on whether its regular use for commercial shipping will be happening any time soon. The study finds that even with declining ice overall, the waters of the Northwest Passage are still chock full of thick ice in the winter, much of which may still be able to persist in summertime, detracting from the predictability of navigation.

“It’s really the first time that we have some quantitative information to inform the discussion,” says Christian Haas, a researcher at York University in Toronto who conducted the research with Stephen Howell of Environment Canada. The study is in Geophysical Research Letters.

Haas and Howell report on “first-ever” aircraft based electromagnetic sensor measurements of ice thickness in various waters that comprise the various possible routes through the passage. The measurements were taken from a helicopter in May of 2011 and a plane April of 2015 — when seasonal ice is at its peak. A sensor was suspended from the aircraft so it dangled just 20 meters above the ice, where it could measure the elevation of the ice below as well as the height of the water. The difference between them lets scientists determine the overall ice thickness.

April and May are not, of course, when any shipping would happen — but it’s a key time to take measurements, Hass explains.

“In order to develop reliable shipping, you need to know how likely it is that the ice disappears completely, and this is why you need to know the ice thickness at the end of the winter, which is the initial condition for anything that happens at the end of the summer,” he says. “What we’ve shown is that the ice is still reasonably thick.”

Indeed, the research found that for most of the ice, average thickness was between 2 and 3 meters. They added that while there was high variability in ice thickness, “there are large numbers of thick ice features with thicknesses of more than 4 m over distances of more than 100 m which have the largest probability to survive through the summer.”

“Even in today’s climate ice conditions must still be considered severe,” the authors wrote.

Granted, ice does decline significantly towards summer, reaching a low point in the early fall. Environment Canada, for instance, lists data showing that minimum ice coverage of waters of the passage often declines below 5 percent at these low moments.

Similarly, the Department of Environment and Natural Resources of Canada’s Northwest Territories notes that transits of the Northwest Passage have been growing of late, observing that “A record number (30) of vessels transited through the Northwest Passage in 2012. In 2013, for the first time, a large bulk carrier transited the Northwest Passage.” Last year, meanwhile, a cargo ship carrying nickel ore (and equipped with some ice protection) made it through without icebreaker accompaniment.

Overall, says the department, “The number of transits increased from 4 per year in the 1980s to 20-30 per year in 2009-2013.” But it adds that most of these are done by icebreakers or by “small vessels/adventurers.” But that’s not the same as major shipping operations using the passage on a consistent basis. “Commercial traffic hasn’t really increased in the Northwest Passage at all,” says Haas.

Or as the paper puts it, “the observed thickness and amount of deformed ice still indicate serious ice conditions which can persist throughout the summers and provide ample potential for encounters with hazardous ice…shipping through the [Northwest Passage] should not be taken lightly.”

Harry Stern, a polar researcher at the University of Washington in Seattle who was not involved in the research, says he basically agrees with the new study — but he draws a distinction between different routes through the Northwest Passage, noting that it is the northern, deeper routes that are most suitable for shipping.

“I basically agree that shipping companies, they can’t really count on a reliably open northern Northwest Passage suitable for big ships until sometime in the future,” says Stern. “But for smaller boats, it’s been open every year for probably close to 10 years now, if you look at the data on transits.”

The new study is quite consistent with a recent, pessimistic paper on the passage by the Canadian Defense and Foreign Affairs Institute at the University of Calgary School of Public Policy, which found that:

Although the Arctic ice cover has shrunk dramatically over the past decade, confirming a clear trend line towards less and thinner ice across the region as a whole, the process has been anything but reliable or consistent from an operator’s standpoint. Scheduling a transit through specific waters of the Canadian Arctic remains both difficult and dangerous. Winds and currents shift the ice constantly, often clogging channels that had been clear the week, or even day, before.

The paper stated that “the much-hyped Northwest Passage routes will remain inhospitable to international shipping for the foreseeable future.” Rather, it suggested there would be a growth in other types of activity, such as destinational tourism.

Similarly, former Coast Guard captain Lawson Brigham, currently a professor at the University of Alaska at Fairbanks, told the Post recently that when it comes to commercial Arctic shipping more generally, it will be a “niche” business for some time.

“There’s so much talk about the Northwest Passage, right, but people don’t know anything about it,” says Haas. “And this was a good opportunity to really provide some quantitative information just to set the stage for anything that follows.”