Just a few years ago, the trip would have been impossible.

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OSLO (AFP) - A trimaran sailing boat circled the North Pole in a single summer season, a feat made possible by global warming and the melting of the Arctic ice cap, the boat's international crew said Thursday.

The "Northern Passage" left the western Norwegian port of Bergen at the end of June and was expected to arrive back there Thursday after first sailing the northern passage off Russia and then the northwestern passage off Canada.

Just a few years ago, the trip would have been impossible to complete so quickly due to the polar ice.

Following in the wake of the Russian ship "Peter I," which sailed a similar route at almost the same time, the Norwegian trimaran is the second vessel to ever complete the mythical voyage in the space of a single Arctic summer.

"Less than 10 years ago the first steel-hulled sailboat managed to get through just one of the passages, and 100 years ago, a circumnavigation would have taken six years," the "Northern Passage" crew said in a statement.

"This is a clear indication that climate change affects the Arctic," it added.

The crew comprises two permanent Norwegian members, explorer Boerge Ousland and navigator Thorleif Thorleifsson, and a rotation of one other Norwegian, two Frenchmen, one Russian and one from Dubai.