Anyone doubting that the Arctic is warming need only look at the figures that track growing commercial ship traffic across the Arctic Ocean from Asia to Europe and back — a trend that could unfortunately accelerate climate change.

Last year 46 ships made the Northern Route passage that hugs the Russian Arctic shore, up from a handful in 2010.

This year, reports the Financial Times, Russia has granted permission for nearly 400 vessels to make the passage.

Along with a number of oil tankers, one of the latest vessels to make the trip from Asia to Rotterdam via the Northern Route was the Chinese cargo ship Yong Shen, shaving nearly two weeks off of its normal seven-week voyage through the Suez Canal.

The surge in Northern Route traffic during the summer and fall months of relatively ice-free waters is made possible by five years of below-normal ice cover in the Arctic.

The National Snow and Ice Data Center, a federally supported research group at the University of Colorado, reports that while Arctic ice this year covers a larger area than it did last year, it remains below the average of the past 30 years.

Of the two sea routes across the Arctic, the Northern Route that hugs the Russian shore is preferred for heavy traffic instead of the fabled Northwest Passage through Canadian waters. The British Navy spent much treasure and many lives trying to establish the passage in the 19th Century.

But the Northwest Passage has also opened up. A number of yachts have made the summer trip in the past five years, and last year two yachts circumnavigated the Arctic Ocean, going east by the Northern Route and returning to Europe by the Northwest Passage. Yachting in the Arctic remains challenging. But at least it has minimal environmental impact.

Not so the commercial use of the Northern Route. Because of the lack of an effective international environmental agreement reducing soot, commercial ships are free to burn dirty bunker oil without removing ash.

The rising number of vessels using the Northern Route will increase the amount of soot deposited on Arctic ice. Soot from burning coal and wood, especially in Asian countries lacking modern pollution controls, already contributes to the Arctic ice melt, according to NASA.

Commercial sea traffic in the Arctic, without effective environmental controls, threatens to accelerate the damage.