This time last year, the temperature in Nunavut, the faraway Canadian land of massive ice floes and tundra islands that comprise the Arctic archipelago, soared above 73 degrees for the first time. This summer, some 1,480 miles from the territorial capital of Iqaluit, the editors of the Harvard Law Review published a study of an arcane Law of the Sea controversy. With each passing summer, the connection between the two grows with each degree of global warming.

At the center of both the physical and diplomatic climate change of this distant region is a remote sea channel — as much a subject of well-loved folklore as navigational reality — known as the Northwest Passage. For centuries it drew European dreamers and explorers, some of whom left their names and lost their lives in the expanse of bitter cold that is home to the Indigenous peoples who, then as now, regarded the intruders as imperialists.

For years, a controversy — a tempest in an ice bucket, you might say — has raged in the vast empty stretches that are swept each winter by high winds and low temperatures: The United States believes the Northwest Passage connects two international bodies of water and thus is an international strait. Canada believes the passage, freighted with resources and romance, is within its territorial limits and is an internal Canadian waterway.

The question grew more urgent in recent weeks as China, increasingly active in Arctic mineral extraction, pressed to buy a gold mine 120 miles north of the Arctic Circle.

Secretary of State Mike Pompeo stirred international waters last year when he dismissed Canada’s claim as “illegitimate.”

One of Pompeo’s predecessors in Foggy Bottom, former Secretary of State John Kerry, said the Pompeo remarks grew out of the Trump administration’s diplomatic style. “The fact that this has even become an issue is a reflection of the way we have treated our good neighbor to the north,” he said in an interview. This summer the Trump administration threatened to impose tariffs on Canadian aluminum and steel.

Here is every element of a bitter diplomatic and economic confrontation, especially since, in the words of the Harvard Law Review, the area’s legal status “will become increasingly important as it becomes ice free during longer spans of time each year,” transforming a 16th-century obsession into a 21st-century preoccupation.

But, as James Kraska, who teaches international maritime law at the U.S. Naval War College and at the Harvard Law School, put it, “both the U.S. and Canada have taken great pains not to make an issue of the very substantial differences they have.”

Even so, Prime Minister Brian Mulroney put it starkly in 1987: The Northwest Passage belongs to Canada “lock, stock and icebergs.” His remarks were in a great tradition of Canadian conviction. One of his predecessors, Lester Pearson, said Canada had a legitimate claim “not only to the land within the sector, but to the frozen sea as well.”

That has become a matter of Canadian faith if not international law. “We say the Northwest Passage is as Canadian as Lake Winnipeg,” said Franklyn Griffiths, a University of Toronto expert on Arctic issues. “Americans don’t traverse Lake Winnipeg.”

But Lake Winnipeg, for all its value as a source of walleye pike and hydroelectric power, is not eyed by the Americans, Russians, Chinese and Europe’s Nordic countries to save hundreds of miles of maritime transit. In 2013, the 75,000-ton Nordic Orion became the first commercial freighter to traverse the passage instead of using the Panama Canal, cutting off 1,100 miles.

“We have done an admirable job managing a stark legal difference,” said P. Whitney Lackenbauer, who holds the Canada Research Chair in the Study of the Canadian North at Ontario’s Trent University. “But as the ice melts and the passage becomes more navigable, this issue will be forced.”

The passage may be becoming more passable, but it is not tranquil.

“It’s still a very dangerous place,” said Michael Byers, a University of British Columbia Arctic affairs expert. “There’s less sea ice but more icebergs — and serious storms. I’ve been in gale winds and 25-foot waves there. Help is a long way away. This isn’t the Straits of Gibraltar. The waters are shallow and poorly mapped.”

Back when the Northwest Passage remained a concept of fantasy and fable — Martin Frobisher’s 16th-century efforts to discover the route, Henry Hudson’s early 17th-century doomed voyages, Sir John Franklin’s lost 19th-century expedition — its ownership wasn’t contested.

“We southerners know almost nothing about the Arctic,” said Griffiths. “We know far more about Niagara Falls than we know about Iqaluit. We don’t get up there, and we don’t know the people who are up there. But we do know there is global warming, and we know that Arctic ice is in retreat.”

Global climate change changed everything — a notion Canadian foreign minister Chrystia Freeland, now the country’s deputy prime minister, acknowledged when she said, “We see the conditions of the Northwest Passage changing with our changing climate.”

The Norwegian Arctic explorer Roald Amundsen and his crew of six took three years to traverse the entire passage in a small sloop called the Gjoa in the early years of the 20th century. The Nordic Orion required 19 days 107 years later.

When Pompeo denounced Canada’s claims at the Arctic Council Ministerial meeting in Rovaniemi, Finland, Canada’s Freeland, the prime-ministerial heir apparent to Justin Trudeau, responded that “there is both a very strong and geographic connection” between Canada and the Northwest Passage. Soon thereafter leaders of the Inuit Indigenous peoples told the United States the Northwest Passage was part of their Arctic homeland.

Since Mulroney and President Ronald Reagan concluded an Arctic cooperation agreement in 1988, the two countries have agreed to disagree over the ownership of the waterway, and for now, the diplomatic waters are tranquil. The United States promised to seek Canada’s permission before sending a Coast Guard icebreaker through the passage. Canada always grants permission.

In recent years, China, the world’s largest shipping state, has been looking northward. As part of its Belt and Road Initiative, China has cast its eyes on what is known as the Arctic’s Northern Sea Route, which runs along the coast of Russia and reduces shipping distances to Europe by more than 3,700 miles. The Chinese have come to call it the “Polar Silk Road.” It is a Northwest Passage by another name.

David M. Shribman is the former executive editor of the Pittsburgh Post-Gazette. Follow him on Twitter at ShribmanPG.