The Arctic Ocean is becoming more accessible for shipping. Most of the increase in commercial shipping traffic has been during summer, noted a recent report from the National Snow and Ice Data Center (NSIDC), primarily through the Northern Sea Route along the coast of Siberia.

But this February a commercial tanker, the Eduard Toll, made the first crossing of the Northern Sea Route in winter. Improvements in shipbuilding and the development of ice-strengthened hull technology are major factors in enabling winter access. Previous ice-strengthened ships could only navigate safely through half a meter of thick ice, compared to the 1.8-meter thick ice that the Eduard Toll cruised through. A fleet of six ships with similar technology is being constructed by a South Korean shipbuilder.

While the Northern Sea Route has tended to be dominated by first-year ice, which typically reaches a maximum of around two meters, thicker multi-year ice—three to four meters thick—would be a hazard even to the newer, stronger ships.

According to analysis by the US National Ice Center, this year’s old, multi-year ice has pulled completely away from the coast and the Northern Sea Route is dominated by first-year medium ice of 0.7 to 1.2 meters thickness or first-year thick ice, measuring 1.2 to two -meters.