Scientists say that over the last 10 years the average size of the polar ice sheet in September, the time of year when it is smallest, has been only about two-thirds the average during the previous two decades. The Arctic Monitoring and Assessment Program, a Norwegian group studying the Arctic, forecasts that within 30 or 40 years the entire Arctic Ocean will be ice-free in the summer.

And so business plans are being drawn up to capitalize on changes in a part of the world that for much of seafaring history was better known for grim final entries in diaries of explorers like Hugh Willoughby of England. He died with his crew in 1553 trying to navigate this shortcut from Europe to Asia, known as the Northeast Passage.

The Russians, by traveling near the coast, have been sailing the Northeast Passage for a century. They opened it to international shipping in 1991, after the breakup of the Soviet Union. But only recently have companies begun to find the route profitable, as the receding polar ice cap has opened paths farther offshore — allowing larger, modern ships with deeper drafts to make the trip, trimming days off the voyage and saving fuel.

In 2009, the first two international commercial cargo vessels traveled north of Russia between Europe and Asia. This year, 18 ships have made the now mostly ice-free crossing.

The voyages included a scenic cruise through the Northeast Passage, departing from Murmansk and arriving in Anadyr, a Russian port in the Pacific Ocean across the Bering Sea from Alaska. “The voyage offered attractions such as abandoned Russian polar stations,” the Australian operator, Aurora Expeditions, noted in its promotional literature.

On some routes, the trip over the top of Russia is now competitive with the passage from Europe to Asia via the Suez Canal. The voyage from Rotterdam to Yokohama, Japan, via the Northeast Passage, for example, is about 4,450 miles shorter than the currently preferred route through the Suez, according to Russia’s Transportation Ministry. (Of course, the Arctic route has a way to go before catching up to the 18,000 ships a year sailing through the Suez Canal.)

But the primary use of Arctic Ocean shipping has been to support other industries heading farther north, like mining and oil drilling, according to participants at the Russian conference.