A new trade route for energy supplies is opening up north of the Arctic Circle as some of the warmest temperatures on record shrink ice caps that used to lock ships out of the area.

This year is likely to rank among the top 10 for the amount of sea ice melting in the Arctic Ocean after heat waves across the Northern Hemisphere this summer. While that is alarming to environmentalists concerned about global warming, ship owners carrying liquefied natural gas and other goods see it as an opportunity. Their cargoes have traversed the region for the first time this year without icebreakers, shaving days off shipping times and unlocking supplies from difficult-to-reach fields in Siberia.

More navigable waters are a boost for Russian President Vladimir Putin's effort to expand his nation's reach in the gas market and for energy companies such as Total SA and Novatek PJSC, which are leading Arctic developments. They also help reduce shipping costs for LNG, benefiting buyers and traders of the fuel from PetroChina Co. to Gunvor Group Ltd.