A recent Congressional Research Service report depicts the Arctic Ocean basin as a shapeshifter. In more ways than one. The icy north is undergoing physical change as warming temperatures open regional waters to shipping for part of each year. And the region is undergoing geopolitical change as countries that front on the Arctic Ocean — and ambitious powers that don’t — eye new shipping routes and, potentially, a fresh source of undersea natural riches.

In all likelihood the coming years will see the top of the world become an arena for strategic competition.

First, consider the region’s physical complexion. Some years back the U.S. Navy’s chief oceanographer projected that the polar icecap would retreat enough each year to open the Northwest Passage, which skirts along the northern coasts of Canada and Alaska, to shipping intermittently by 2025. The Northern Sea Route, which passes along the Russian seacoast, will be open for about six weeks by then. And, most strikingly, a brand-new Trans-Polar Route will be ice-free for a couple of weeks annually.

Going over the pole cuts upwards of a third off a voyage from Asia to Europe depending on the origin and destination seaports and the route taken. Shaving distance saves time, fuel and wear-and-tear on hulls and crews. Small wonder shipping firms are slavering at the prospect: Shorter routes cut costs and boost the bottom line.

Climate change also will improve strategic mobility for navies and coast guards. Russia, in particular, stands to benefit from new shipping lanes. Russia’s difficult maritime geography has always compelled, or at least tempted, naval commanders and their political masters to fragment their navy all over the map. During the Russo-Japanese War of 1904-5, for instance, St. Petersburg kept fleets in the Baltic Sea, Black Sea and Pacific Ocean, weakening each one. Worse, potential adversaries — the British and Ottoman empires, in particular — controlled the most convenient sea routes for unifying naval detachments for battle and took the opportunity to make things tough on Russian mariners, closing the Turkish Straits and Suez Canal to Russian warships.

The Russian Navy met a catastrophic fate by 1905 after the Imperial Japanese Navy crushed it piecemeal. Climate change will alleviate this timeless dilemma in part, letting today’s Russian Navy move warships horizontally through Russian-dominated seaways for part of each year, rather than take the more vertical, contested routes whereby the imperial navy — of necessity, owing to the solid icecap — traveled between theaters. As a result, Moscow has moved aggressively to consolidate its northerly strategic position, assembling a formidable fleet of icebreakers and constructing shore infrastructure to support Arctic operations.

That the Arctic Ocean will be a feasible theater for nautical endeavor, though, does not mean it will be a hospitable theater. Far-north waters will be dynamic and turbulent. As temperatures drop and rise with the seasons, the ice will advance and recede in fitful ways. Navigation will pose challenges into the foreseeable future.

Second, there’s a political dimension. During World War II geopolitics guru Nicholas Spykman pointed out that a geopolitical region is far more than its geography. While geographic features are fixed for the most part, a region’s geopolitical terrain changes shape over time as regional contenders come and go, rise and fall.

Spykman also observes that humanity can bring new maritime theaters into being. That’s what happened when the Panama Canal opened in 1915. As an offshoot of the British Empire, the United States traditionally looked eastward toward Europe in commerce and politico-military affairs. Spykman contends that in a cultural sense, digging the canal picked up America and swiveled it southward toward the Caribbean Sea and Gulf of Mexico, where shipping lanes bound for Panama — and thence the Pacific — now ran.

In effect, the canal teleported U.S. east-coast harbors thousands of miles closer to Asia. New York now lay closer to north China than did the British trading port of Liverpool measured by the distance vessels had to steam. Overnight an artificial modification of geography granted U.S. merchants an advantage over their British competitors.

An accidental byproduct of human activity — not deliberate engineering works — is remaking the polar region. Even so, Spykman would instantly grasp Arctic states’ maneuvers to exploit climate change. Russia was the first mover in Arctic strategy. But Russia’s coalition partner China has also evinced a keen interest in the region, styling itself a "near-Arctic state."

A mix of motives prods Beijing to involve itself in northern climes. The economic dimension is huge, and probably predominant. China’s outward-facing trading sector can profit from cutting voyage distances, even if only for a few weeks per year. Chinese Communist magnates fret constantly about American containment along the first island chain, so it makes sense to diversify the portfolio of options for the Chinese mercantile and naval fleets. And if operating off North America vexes Washington, so much the better from Beijing’s vantage point.

Does this add up to serious trouble for the United States? Doubtful. The shapeshifting polar sea will remain hostile to marine endeavors for the vast majority of the year. Plus, Beijing’s foremost strategic priorities lie in East Asia and the Indian Ocean. These commitments have first claim on finite Chinese maritime resources.

Still, opportunities to make mischief for a rival in its own backyard — even through token efforts — constitute part of strategic competition. Chinese leaders bristle at U.S. military endeavors along the East Asian seaboard. Why not repay America in kind?